Need to get around to filming a follow up to this and revise the explanation. The pitching up/down phenomena we experience when the centre of lift of the foil is not aligned with the COM of the system is actually due to the rider temporarily unweighting during in a turn, dropping down down a wave, or pumping, rather than centrifugal force. More to follow!
Just my $0.02 for prone foil surfing, it's much easier to paddle into waves and catch them with the mast all the way back. The downside is it's easy to put too much weight up front and crash down. You may also tend to struggle to balance your weight properly and have the ail of the board get hit by the wave to take off. If the mast is all the way forward, you may get too much lift and not be bale to hold down the board on take-off and end up missing the wave. So you gotta find the sweet spot somewhere in the middle. Hydrofoil wing screws are the best way to resolve this especially if you will be swapping boards/foils/wings often. It lets you easily adjust your mast in the water and then find the sweet spot. Take note where that spot is. Your board may have markings, if not just use sharpie/whiteout/tape. Awesome video with showing how the forces balance out. The BIGGEST thing people often forget is the tail. A tail/stabilizier can make or break your foil session. Fast wings needs fast tails. Front wings with tons of lift need a tail with tons of lift. Remember, your front wing wants to climb up in the water at speed while the tail is trying to dive down, effectively creating leverage on the mast to lift that board up. Experiment with different mast position, front wings, tails, shims, fuse length, etc. Have fun!
Wing screws are a great way to dial in mast position! Once you get your spot figured you do you change them out for regular hardware for less drag when paddling/taking off/touching down or find that it's minimal?
One additional thing I forgot to add in the video is that positioning your foil a bit further back in the tracks than the balance point on your prone foil board can make your pop ups easier, especially if you are on a lower volume board. This lets you paddle in without worrying about getting too much lift from the foil as soon as you catch the wave and overfoiling. Once you've dialed in your pop up technique, and moved on to smaller foils this is easier to control and having the lift coming from the correct position will actually make your setup more efficient at catching waves at the cost of being a bit more difficult to control during the pop up. On the other hand placing the foil too far forward can making prone foiling extremely frustrating and dangerous for beginners who can't control the sudden increase in lift.
If I switch to carbon and thereby reduce mass behind the center of balance, I must move the mast forward in the track to put additional board mass behind the center of balance. Thanks for these invaluable videos. Wingfoiling is the most difficult endeavor I’ve attempted other than flying a helicopter. They are very similar in their simultaneous requirement of somatic ‘feel’ and intellectual understanding of the physics. With wingfoiling, the physics insights are underrepresented on YT
Thanks @jsibleytube! For me, having an understanding of the physics really helps my progression. Everybody learns differently though, so very glad to hear our videos have been helpful to you.
Ty for this theory video ! Im a wingfoil instructor and a loooooooot of people ask me where i put the foil, and i showed them this lift technique, now i understand more in details! But as u explained i recommanded to them to move them foil a bit the foil back cause lot of beginners cant handle the lift Carbon mast lighter = move the foil foward
Stoked to be able to add some theory to your lesson plan @vabrial! Correct on the answer! All else being equal, a lighter foil will be balanced when it is further forward in the tracks than a heavier foil.
I find every board has a specific foot position based on volume distribution front to rear. So when you find that when you go to stand up then that is what you use as a reference to where your mast will go. But I have been using the lift the system with your finger method to get a starting point
That's a great point Scott and something I should have addressed in the video. The center of buoyancy of a foil + board will generally be a bit further forward than the center of mass of the foil +board due to the higher density of the foil vs board and increased mass in the rear of the board to reinforcing the tracks, deck, leash plug, etc. I prefer to align the foil's lift with the center of mass of the system for the reasons mentioned in the video, suppose this means I would need to shift my weight a bit further forward when moving slow on a high volume shorter board but I think the tradeoff would be worth it to have balanced flight characteristics. I'm generally on sinkers or longer shapes so haven't really played around with this too much so can't say 100% though.
I initially balanced the center of my foil on my fist to choose a mast position (board hangs flat) as you describe. But I noticed as soon as I got onto foil, I had to jump back a couple inches. My buoyancy was forward of my center of foil lift. For those of us on body weight plus ~10-20kg boards, I found it better to center the lift of the foils with the buoyancy. That meant further forward, which was also a lot more fun. My experience with gybes is that my speed through the gybe changes dramatically with wind conditions and 'arc', so learning to compensate for too much or too little lift needed to become a muscle memory - it was different all the time, but now I rarely notice it.
I agree. Start with foot placement relative to buoyancy then position foil mast. The explanation of forces in this video doesn't make sense to me and I have a pretty good physics background (see my other comment)
I prefer to base mast position based on center buoyancy because Im a beginner and I dont want to move my feet once up on foil. Otherwise all points about forces and stable flight are spot on. In a perfect world, the center of boyancy would be closer to the center of mass.
@@NeuralEngin33rI think you’re spot on. I find that I need much less wind energy to get up if the foil is in the correct place relative to the bouyancy of the board
I've watched several videos proclaiming the same technique, and always thought it was somewhat simplistic, but until you responded to someone saying that the technique balances mass "while foiling" and you can make adjustments in the transition from taxi to foiling that I realized the genius of the technique. I had always thought the latter was key (you wanted same foot position for taxi and foiling). But thinking about it, your mass is heavier when turning, also lighter when being lifted by the wing in a gust. Basing the positioning so that the balance point is indifferent to body mass seems like the right idea after all. Is the board speed a consideration at all? We sail at all different speeds all the time, but there is an average "crusing speed" for a lot of us. When going faster versus slower, is the center of lift of the foil actually different (involving shifting feet) or are we just tilting the board flatter to keep from breaching?
Great question David. It is indeed a very simpe technique to solve a rather complicated problem. Just so happens to be my favorite type of solution! My thinking on the matter has evolved since making this video but most of it still holds true. I think for early beginners it is important to balance the centre of bouyancy with the centre of lift so that they don't need to move their feet when transitioning from taxiing to take-off. However, as one progresses (and as you pointed out) it is more important to have the mass of the system balanced over the centre of lift. This often means placing the foil slightly further forward. A key time this is noticed is during pumping. If the foils is further forward the nose will have a tendency to pitch up during the unweighting phase of the pump and conversely if it is too far back it will pitch down. Since keeping the board "flatter" during pumping is desirable this is another factor to consider. Having the nose pitch up gently during the pump is nice though since it makes it easier to maintain altitude so for this reason I've been putting my foil a touch more forward recently, better to err this way since pitching down during the unweighting of the pump is counterproductive. Your question about the centre of lift moving with speed is a good question but also tough to answer fully. One should think about angle of attack and speed as synonymous when it comes to foiling. Since lift is fixed the two are directly related. The centre of lift moves with speed/angle of the foil but more or less depending on the wing design (planform, section, twist, etc). The other factor is that most brands do not have their tails perfectly tuned to balance the pitching moment and drag moment created by the foil. So a lot of the reason people are moving their weight/feet around at different speeds is not so much to deal with the moving centre of lift but rather the changing moment on the foil which is the sum of the drag moment and pitching moments of both wings.
Would love a deep dive follow up video! In earlier comments buoyancy was mentioned and I think this is one point that could be explored more. To me Kane de Wilde’s trick of balancing it - out of the water - will *always* result in mast being too far back. When riding on foil, the foil, fuse, stab and part of the mast are under water and consequently not as heavy as in air. Therefore we must consider the center of mass of the system while flying through water. I wonder if there is a good rule of thumb for adjusting Kane’s rule of thumb. 😉😄
@bcransto1 agreed there is two ways to look at balance, when the board is on the water vs when the board is flying. In my option, the first case is really just about aligning the net result of the centre of buoyancy + centre of gravity with the centre of lift so that the riders weight distribution does not need to change at takeoff. This video is focusing on the second which is the ideal position when riding and assuming the user will make the necessary adjustments during takeoff to have a more balanced ride. Good design can bring these aspects together but of course is not the only concern so must be weighed against other factors. In a poorly designed board they could be way out in which case the rider would need to choose one or perhaps compromise in between. Gets complicated fast, I really like your suggestion of a deep dive follow up though so will start thinking of ways to simplify it for a video :)
It is very insightful. I never think of it. Thanks for your sharing. Originally, I thought moving mast forward can be compensated by moving body forward. But actually it is more complicated than that. Thanks
Thanks Lawrence, that does work but as you say it's more complicated especially when taken to extremes. The biggest time I notice the imbalance now is actually when pumping, changing feet, or dropping down a wave rather than turning which I described in the video. Need to work on a follow up as another couple commenters have mentioned!
One thing I used to do was set the board and foil upright on the sand as if you were riding it and if the board fell forward, move the mast forward until it could stand upright by itself. Nice video again!! 🤙🏼
👍🏼Great video / explanation. With a lighter Mast for my understanding you have to move the mast little back to compensate the stronger (same) lift force - correct
Thanks Mike! With a lighter mast you indeed want to move it back since the reduced weight at the back end would make the system front heavy so the mast is moved back to compensate :)
Congratulations. Many thanx. I'm impressed by the quality of your video, this is so clear and smart. May be useful to better explain the fact that when we turn, the board "becomes heavier" because of the centripetal acceleration. One question: if I keep my foil the same, but changing only the front wing, I have to move the position of my mast practically, to maintain a good balance when riding (E.g. replacing a 1300cm2 front wing by a 900cm2 front wing --> I've to move my mast backward). Looking at your video, only focusing on the weight of the foil & board, I do not see how to explain the fact that I need to move my foil forward or backward depending on the surface/shape of the front wing.
Thanks @Louardoul, you're right on a better explanation being needed on the board getting "heavier" being required. I didn't want to confuse things too much by going down a rabbit hole in the video but will try to find a better compromise in the future between skipping over something and going too deep in the weeds! I responded to a similar comment below with this explanation: Hi @gwendal5620, really appreciate your comment. I'm sure there are lots of other folks out there with the same question so I'll try to provide more context. The board getting "heavier" can be thought of in the same way as that the old trick to keep water inside an upside-down bucket by spinning it aggressively overhead with your arm outstretched. The change in direction of the bucket is constantly accelerating the water towards your shoulder so the water seems to constantly "pull outwards" on your arm. You can even feel the same during hard turns on your foil since you'll notice your legs are under more force (your body weighs more because of the angular acceleration). The same extra force that is making your body heavier is also making your board heavier and will cause it to pitch nose down if the foil is too far back or nose up if the foil is too far forward. Here's a good link if you're interested in the physics of centripetal acceleration: courses.lumenlearning.com/suny-physics/chapter/6-2-centripetal-acceleration/
Regarding your question on changing the front wing there are two reasons why you’ll want to reassess your track position: The center of lift of the new wing could be further forward or backwards from the old wing. The weight of the new wing could be different (less significant) Interestingly, changing the stab or even the shim/fuselage length will also require an adjustment to track position to achieve a perfectly balanced setup. Even though the center of lift of the front wing is unchanged changing the lift from the stabilizer will result in a change to the location of the center of lift for the whole foil as a system. To make matters even more confusing the center of lift actually moves with speed! This can be mitigated by good wing design, but it’s ultimately why the best way to tune is to get out and ride at your preferred speed and throw some hard turns and feel if your board is pitching up or down. The upside down balance trick is super helpful to get close but never intended to be a 100% solution. Hope this is helpful for your riding and understanding of the dynamics! Tuning can be a never ending process, but like many things most of the benefits are had by getting it 90% of the way there. Can be a lot of fun to tweak gear and see the results in your riding, with our equipment we’ve gone to great lengths to make tuning easy and intuitive so riders can access the top performance of our gear and focus on their progression.
Happy to@@Louardoul , thanks for the great question - I'm sure there are many others wondering the same! Centre of lift can vary between wings and since the distance of the wing from the mast has a big affect on feel, different wings are placed at varying distances from the mast.
Interesting video. In your exercise with the arrows, why isn't there a downward arrow above the stabilizer? Isn't that one of the primary purposes of the stabilizer? I guess it's possible for a stabilizer to have neutral lift (or even positive in the canard case). But, I think, most stabilizers have negative lift -- specifically to counterbalance the weight of the board that is in front of the main wing. Is that not true?
This is very true David! I'm summing up the forces though for the sake of simplicity. The downward force of the stabilizer is relatively small compared to the lift from the front wing, but more importantly, there is a rotational moment created by both wings and drag from the system moving through the water. These are the forces that are counteracted by the downward force of the stabilizer acting on the centre of gravity of the system along the axis of travel by the length of the fuselage. Breaking down this stabilizing force into this counteracting moment, the downward component effectively reduces the total lifting force of the front wing but does not "move" the vector's horizontal position assuming the lift is aligned with the centre of gravity of the system. This is because the moment created from transposing the downward force from the stabilizer to the centre of mass is balanced by the other forces mentioned which would otherwise cause rotation. Sorry for the long answer to a simple question! I break down these forces more in our stabilizer video if you're interested in more.
I didn't understand why things change when we turn. I agree about the increase in lift of the front wing, but why does this increase in lift cause the board to dive if the foil is at the back? During a turn, the weight of the board's center of gravity remains in the same position with the same intensity, so proportionally it is weaker compared to the lift of the foil, so the board should pitch up ? Thank you for the tip about balancing the board upside down.
Hi @gwendal5620, really appreciate your comment. I'm sure there are lots of other folks out there with the same question so I'll try to provide more context. The board getting "heavier" can be thought of in the same way as that the old trick to keep water inside an upside-down bucket by spinning it aggressively overhead with your arm outstretched. The change in direction of the bucket is constantly accelerating the water towards your shoulder so the water seems to constantly "pull outwards" on your arm. You can even feel the same during hard turns on your foil since you'll notice your legs are under more force (your body weighs more because of the angular acceleration). The same extra force that is making your body heavier is also making your board heavier and will cause it to pitch nose down if the foil is too far back or nose up if the foil is too far forward. Here's a good link if you're interested in the physics of centripetal acceleration: courses.lumenlearning.com/suny-physics/chapter/6-2-centripetal-acceleration/
1. If the board has rocker in tail, sure the posistion is very important, but as no rocker design I think the better is get good filling in stand and foot pressure. 2. Flip the board to find the gravity center is trick especially use the palm of hand ----you cannot use the finger to make the correct result due to your finger cannot take the weight, but you wide palm will make it wrong especailly the wing has convex curve on top, just little tune the palm will tilt the system. A better idea would be to tie a string to the board and check the system's balance.
Thanks for your comment Bruce, I'm not quite sure what you mean on point #1. Regarding lifting with the finger, I form my hand into a "knife" and lift with my index finger/knuckle which is supported by my other fingers. Found this works pretty well.
Thanks! Perfectly balanced will be easiest since the board will fly straight even without your body weight on it will be easiest for the run up and jumping on. Running with the foil a bit further forward than balanced will bring the nose up "automatically" when you unweight which is nice but you need to be more conscious to drop the angle of the board before loading the pump or you will loose a lot of efficiency. Most really small dockstart boards end up with the centre of lift ahead of the centre of gravity based on the small size and limited track placement.
Congrats Greg - excellent video. Thank you. What do you think about the rake of the mast. I’m playing with it for a little while now and I would love to have your opinion on how it would affect riding position and performance. 🤙
Thanks Giovanni! Rake is a very interesting and often ignored factor of the mast, stoked you are taking an interest in it! Rake can make turning response more "uniform" through the water column since as the mast is submerged deeper it it's centre is located closer to the centre of turning of the system. This mitigates the feeling of the foil being "too loose" when close to the surface and "too tight" when deeper. The downside of rake is that it affectively increases the chord and length of the submerged mast when the angle of attack of the foil is at around neutral or greater. This means that it increases mast drag at higher speeds while decreasing it at lower speeds. For these reasons Omen using only a very slight rake in our masts.
Great video, Greg. I actually had a lightbulb moment a week ago when i realised i had been using too small of a tail (KD13R)/not enough shim with my 170 progression. It had kind of evolved that way starting with a long fuse then switching to a medium without changing tail or shim because i was using the 170 in overpowered conditions a bit, trying to reduce front foot pressure on bigger bumps..only now realised i was loosing the upward momentum for turns/having a tendency to nosedive in turns..Also, i got so used to it that i didn't question my tuning, but kept wondering why i didn't feel small waves and had some problems pumping..at first i put it to my shitty technique but finally tried more shim..just swichting from 0.5 to 1.0 deg made a huge difference.. Next will be a bigger stab. Regarding mast position, when winging you also have to consider your foot position has to stay balanced with the centre of buyancy/volume to avoid nose/tail diving. Hopefully your straps and masttrack are designed balanced in that way, i had a board where it wasn't so i had to start further fwd and then move feet back..sold it after a while..
Awesome, always nice to have those breakthrough moments! And figuring it out the hard way means you'll never forget it! Will be doing another video on tail wing tuning but spoiler is I like to go up to max speed and have the tail adjusted to be stable in this position (if board feels nose down pitchy add more shim or use a larger tail and vice versa with board feeling nose up pitchy). Totally agree with your point on balancing the buoyancy with foot placement, unfortunately this is up to the designer and is often overlooked in our quickly evolving sport. As the user can't do much to change it other than what you did! cheers!
@@omenfoils Thanks Greg this is interesting, looking fwd to that video. Will check trim at top speed next time out. I guess trim at wing powered top speed will be slightly different than wave powered due to the added forces of the wave. The added speed will add lift and change pitching moment depending on foil and stab tuning in both cases. But i should think depending on your position on the wave the circular wave motion might add or subtract pitching moment. Also, the locked in feeling racing down a wave overpowered might be either too much front foot pressure or not enough which creates a negative moment against the turn direction. Kind of a fine line to tune if the foil wasn't designed for that conditions. Reminds me of setting back your snowboard bindings for powder on a non long powder nose shape but then having too much edge in front on slopes..
Great discussion@@andiabel212 , there are definitely lots of subtleties difficult to go into detail over in text. I believe winging and surf tuning should be the same except for niche cases. The foil experiences the wave motion as additional "lift" when riding or rather a change in the freestream velocity. Ultimately in either case the stabilizer counteracts the pitching moment created by the wing but more importantly in my opinion the drag from the foil which has quite a bit of leverage relative to the "control centre" pilot. Very extreme moment compared to any other examples of flight that I am aware of.
Great video explaination! I can’t wait for my next session to test some. I’ve been having trouble with my experiments, changing lots of things in short succession. This should help me a lot. I ride an inflatable 105 L with a carbon setup. So far I find the mast way back and a small +0.5* shim seems to work well. I’m fine on level flight and can turn OK, struggling with foot swap with too much up pressure on the front foot. Your description of turning dynamics should really help me correct! Thank again!
happy to help Maury! If you feel a lot of pressure on your front foot when going fast having a bit less tail shim will help reduce that. Usually front foot pressure is helpful in foot switches though - are you leaving your front foot on until it is replaced by your former back foot before stepping back?
I think there is too much front foot pressure. The reaction when I lift it is too great. My 0.5 shim should reduce lift. I do best when I jump switch feet. Shouldn’t I be able to step switch? I do fine at everything else. Flying level, carving Ss, even toeside riding is coming along. I’m just stumped on the foot switch.
@@mauryjacob5363 stabilizer shimming is a complicated topic which I'll be doing a breakdown on in the next few weeks. If you feel too much front foot pressure you could try standing further forward or reducing the angle of attack of the stabilizer (shimming the front of it UP or rather trailing DOWN). I'd really recommend the step switch since it is so much more consistent. Jump switch I think of as more of a "trick" fun to play with but not a "go-to" if you are looking to get on a wave quickly. Try bringing your feet very close together so they are nearly centred over the lift of the foil, also keep your front foot pointed quite far forward so there is room to move your back foot beside it. As soon as your back foot touches down to the new forward position immediately send your old front foot backwards. If you have the wing more overhead at this time and pull in for some extra lift it makes it even easier. Hope this helps!
All good topics. Yesterday I tested your mid-chord hang suggestion to balance the board weight over the foil. The back of the mast read at 10 cm mark when the board picked up level. That is a full 13 cm forward of where I was riding with the mast all the way back. That is where my feet find the strap positions pretty comfortably in flight. I ride smoothly there but as I said the front foot seems too heavy. The nose rises fast when I lift it. I wonder if the super lightweight nose on my iFly 105 inflatable affects that weight balance point? I am awaiting wind to test ride in that forward position. I will be surprised if it doesn’t porpoise on liftoff.
Great videos on this subject Greg! Got a question for you: When winging in a straight line standing centred on top of the board and performing no other special action(s) I constantly have the feeling the board wants to "dive" (go down with the nose). I have tried to move the mast further forward, but that didn't change this feeling, I just had to stand a bit forward to compensate for that. I also tried to achieve the same by changing the angle of the stabiliser (I had it in neutral (not shimmed) initially), but it also didn't change anything on that "dive" feeling. And in the end I liked it most in the neutral position anyway. The strange thing is, that when I ride down a wave and hold the wing by the handle, the whole combination really performs well and the diving feeling totally disappears...??? Any ideas what's happening here? Any recommendations?
Thanks Ron! To answer your question it would be really helpful if you could try this during your next session and report back: Stand and ride around on your board as normal and ride around to confirm you're comfortable. Ride at a medium/slow pace and note where if the board has this tendency, increase your speed to medium fast and pay attention to the same, finally go as fast as you can and see how the feeling is changed. Don't move your feet at all through this process, once we know how the foot pressure/nose down dive feeling is changing relative to speed we can diagnose what is wrong with your tuning. Looking forward to hearing back! Greg
Dear Greg @omenfoils I just tried out your suggestion: When going slow, there's a slight raising tendency (nose up feeling) that I need to compensate by giving more front foot pressure. So I'm gliding above the water but don't have the board level with the water surface (nose up a bit). After a while, I manage to level out the board after which the board accelerates and reaches a medium speed. I now stand balanced over 2 feet, but I feel the constant diving tendency (nose down). Additionally I can say that this is the position and speed I'm in like 90% of the time. When I push to go to higher speeds, I can keep the board level with the water surface standing balanced over my 2 feet. However it feels like I'm on a bumpy road (in the up and down sense). Not stable at all and I have to correct constantly. By the way: All the above with my feet in the same stance/position. Does that make sense?
@@RonKolijn Totally makes sense Ron. Track position won't help this unfortunately. You either need a larger stabilizer, more angle of attack on your current stab, or a longer fuselage if you have one. I'd try shimming the stab first, make sure you are shimming the leading edge "downwards" relative to the direction of flight (ie. not down when your foil is flipped over and you are working on it). Start by adding 2.0 degrees, then try 1.5, 1.0, and 0.5. Choose the shim that provides most even foot pressure at high speed. Riding will feel more secure if you err on the side of a bit extra front foot pressure (more shim) but you'll get a touch more glide and low end by going the other way. Most folks are better off with a bit extra front foot pressure. Please let me know how it goes! Greg
@@omenfoils Dear Greg, I had an 'early-bird' session here in Holland this morning, as I was eager to try your suggestion(s) This morning I have put my stabiliser to the maximum angle (I own an AK Foil, that works slightly different, but the effect is the same as shimming) And guess what; the 'nosedive-feeling' totally disappeared! On max-speed in a straight line, it's still a bit bumpy, but far less than before, very well manageable. I really didn't expect this, as I thought it would slow down my foil and give me too much front-foot pressure, but no, all fine! This video and the one on tail wing shimming have made a lot of things more clear to me and certainly have helped me. And to top it off, your personal recommendation was the cherry on the pie. Big thanks to you Greg!!!
@@RonKolijn Right on Ron, very happy to hear it! Thanks for popping back in to share. This early in the sport there is still lots of misinformation and equipment available that does not work well out of the box - certainly serves to make things more interesting though! Try reducing the angle of the shim bit by bit to get a touch more performance, and let me know if you'd like to get your hands on some Omen gear :)
Nice clear explanation. I have a question. My and my girlfriend share equipment. If she rides with the foil placed where I use it she needs to stand too much forward, so I usually move to mast back when she's riding. She is 20kg lighter than me. Axis HPS830 (circa1000cm2)
I think the mast is behind the center of mass of the board+foil assembly, so making it lighter would move the center of mass of the assembly forward, so to keep the system balanced would you also have to move the foil forward in the tracks?
Exactly right @nathanielmorbey! All else being equal, a lighter foil will be balanced when it is further forward in the tracks than a heavier foil. Interestingly this works the opposite boards, with a lighter board you actually have to move the foil further back in the tracks. The phenomena explains why foil positions are moving more and more towards the forward as board size increases and in the extreme case of 8' downwind boards almost in the middle.
Greg, I'm 74 years old and probably too new to the sport to ask this question but... My long active life has given me some persistent right knee (back foot) pain after an hour of regular stance riding. I try to switch to goofy but on a good day the riding is %80-20. Would you suggest a track position that can lighten the back-foot loading? I read on forums of riders who never switch feet and this leaves me confused. Note: I still crash during foot-switching
Hey Kip, the easiest way to lighten the back foot loading is actaully just to stand further back on your board. If your foil is already in a balanced position you should keep it as is, but standing further back relative to the foil will put more pressure on your front leg. Have you checked out our most recent foot switch video? I definitely agree foot switching is incredibly important for keeping the body healthy if you're winging a lot!
Thanks @Elninosurfcenter! This is an interesting point and something I think is very often misunderstood. All else being equal, a larger foil has the potential to create more lift, however all this means in reality is that it will get you up on foil at a lower speed. Any foil you are riding at steady state is providing the exact same amount of lift (your bodyweight + board + foil - weight of water displaced by submerged foil). Any more lift than this and you will be rising, and any less lift and you will be falling. To create this amount of lift it is the speed and angle of attack of the foil that change. I'm not sure if I have explained this concept well, please let me know!
@@omenfoilsi have 4foils that have area of around 1000 (axis bsc, hps, art and spitfire) i put them in different position as they have more or less lift.
Hi @surfdocsteve, center of lift isn't easy to pinpoint since it's affected by multiple things like foil shape, sweep and actually even moves around with angle of attack/foil speed. Additionally, the center of lift of the foil as a whole is effected by the downforce of the tail which changes significantly with angle of attack too! So ultimately, I think the only way to really dial in a setup is to get a good approximation, then ride and adjust based on feel. The important part is to perform hard turns and see which way your board is pitching and make micro-adjustments accordingly. Sorry for somewhat avoiding your question!
@omenfoils in the video you suggest using the middle of the chord length. Seems like a good rule of thumb, and then fine tune from there. I'd seen this technique in another video, but Thanks for great explanation, it helps alot to validate the approach.
Hi Greg, very clear and profound explaining, just like in your other videos! Even though you are technically right, I think this explanation doesn’t quite hit the nail on the head though. Even though the boards center of weight has a bigger leverage onto the center of lift, there is still the rider on it, who has less leverage but a substantially higher weight. I would assume compared to the riders effect onto the center of lift, the board's impact is rather unsubstantial. And then in a turn we do not pull 8g like a fighter jet. I would assume around 2g in a very tight and snappy turn. So for the average rider, wo doesn’t do that kind of supertight turns, I think it’s much more important, to have the mast positioned in a way that it aligns with the board floating neutrally, like someone commented before. This way, when you transition from the water into flight, no weight shift is needed. I partially also disagree on the recommendation for beginners. It may be useful for the absolute first timer to not get the foil flying in any way before he/she gets familiar with board and wing handling. After that I recommend to put the mast to position about in the middle of the track (depending on foil and rider weight obviously), to get a feel for the foil lifting. With the mast all the way to the back it’s hard to even feel the foil flying an when you move back all the way on the board you will lose all the speed because this will sink the tail. Just my thoughts, I appreciate any discussion and keep up the great work! Cheers
There is something missing on the physics side to explain the phenomena, will keep working on it for a follow up video! Track position is of course a personal choice, my recommendation for intermediate and above riders is to optimize for turning and hopefully choose a board that is well balanced in buoyancy in this position. If this is not the case I still think it is better to have to adjust your feet after a start than compromise on every turn but of course there is no right answer on that just preference. I agree on your recommendation for beginners, I had meant to say that as soon as they are able to get on foil to adjust the foil to the proper position. "Middle" of the box can be difficult since various foil and board manufacturers all have different track positioning and distances from front wing to mast plate, foil weight, etc. Thanks for the engagement - great to have discussions like this with other passionate foilers!
I started winging a 6’9 KT Dragonfly recently (love it), with Takuma 1095/1440 and Lift 170. Currently I feel like I have to put all foils at the very back of the tracks, but this might change with more sessions. I tried the balance method in this video and there’s no track position where the board is even close to balanced. :D I suppose you’re saying that this means the board will become fore-aft unbalanced in hard carves?
Hi @mirzapirza, does the board tip nose down or nose up when you try the balance trick? But yes, ultimately if the track placement does not allow the centre of lift to be aligned with the centre of gravity of the system you will have to shift your weight progressively more the harder you turn in order to compensate unfortunately. It is something people get used to, it's just easier when everything is aligned, feels more intuitive and controlled, and lets you be more aggressive.
Hi@@mirzapirza , if it tips nose up when balanced then I agree that means the foil is likely positioned too far forward to be ideally balanced in turns. One point to note is as board length increases the tracks appear to move further forward (when viewed relative to the tail). However, if they are staying the same distance from the board's center of gravity they are actually not "further forward" at all. The distance from the tail is an easy reference point but not very relevant based on all the different board shapes, lengths, and weight distributions. Unfortunately it has become the industry standard since it is easy to measure and visualize.
I was cleaning the kitchen and clicked, hoping for some nuanced insights on mast position. Whatever people are experiencing in turns with board dip is most likely not related to the mast position and the moment of the board being forward of the center of lift. (It always is on mine). The rider has a far greater effect on moment than the board can possibly have in any mast position
Thanks Ian, I don't disagree. I made a comment a few months ago that I need to film a follow up but it's probably buried. The pitch up/down of the board with an "off centre" foil position is created during unweighting and weighting the system rather than turning directly. I would add though that while rider skill and input is the most important variable and good riders can adjust and compensate for "poorly" tuned systems or even reap benefits from certain tunings which would cause an intermediate rider to struggle. Ultimately I'm trying to find to provide the most accurate advice for folks to best understand and improve their equipment but at the end of the day the best way to improve at foiling is foiling more :)
I seem to be the only one but this doesn't make sense to me! You combine together the forces from each foot into one force and then the weight of the foil/board into another. But you leave out combining the riders weight and board/foil weight to create another single force. Ultimately it's the position of the force from the combined board/foil/rider weight versus the lift from the front wing (ignoring any stabiliser effects) that affects the balance of the foil. In level flight the centre of gravity of the board/foil/rider will be in the right place to balance the lift from the front wing. As you say, the downforce during the turn will increase but that applies to the total board/foil/rider system. It won't cause the combined downwards force to change position. If it was balanced going into the turn, then it wouldn't get out of balance during the turn. You say the extra leverage from the board weight out in front is significant but ignore the corresponding increase in the riders weight behind the wing creating a counteracting torque. In setting up the board I would follow these steps: 1) Place the footstraps relative to the bouyancy of the board so that I can comfortable stand in them when stationary and pump the board up onto the foil when starting 2) Position the foil mast to get balanced foot pressure when foiling
@oldboywindsurfer, you're right on the money with the explanation lacking. There is an imbalance in the forces during the turn by definition. During a turn the wing is in roll and a portion of what was the lifting force points towards the center of the turn. This force needs to exceed the enertia of the system in order to maintain the direction change. This sets up a rather complicated 3D system of forces which results in the phenomena of nose down pitch for a foil position too far back and nose up for too far forward. My explanation is oversimplified to the point of being flawed but the phenomena it describes and corrective measures make a big difference to performance. Will work on a better one when time and resources align - still trying to figure out how to explain and show the concept. My animation team is made up of a pair of Crayola scissors and printer low on toner, so 3D visualization are bit out of scope at this time! That being said I strongly believe that for any intermediate to advanced foiler the most important aspect of track placement is to achieve balance in turns. I agree for some board designs this could mean you have to adjust your feet after water starting which is not ideal, but ultimately what part of the foiling experience are you trying to optimize? :)
Nice video, i think having a lighter carbon mast or a lighter mast will put more pressure on the front wing and you will have probably to move your foil a little more to the back. Ps: apparently im wrong i checked your answer bellow 😂 anyway the more plug and play foil i got and the more happy iam i got the perfect combo at the moment no shim nothing, i had a armstrong previously and it was a nightmare to fly , i never found the right setting with it end up selling the whole quiver of foil after 6 month.
Haha, yeah I chose that setup because it does seem a bit counter intuitive. We strive to make our gear as easy as possible and provide specific tuning advice to ensure customers can "set it and forget it" to focus on riding :)
Need to get around to filming a follow up to this and revise the explanation. The pitching up/down phenomena we experience when the centre of lift of the foil is not aligned with the COM of the system is actually due to the rider temporarily unweighting during in a turn, dropping down down a wave, or pumping, rather than centrifugal force. More to follow!
Just my $0.02 for prone foil surfing, it's much easier to paddle into waves and catch them with the mast all the way back. The downside is it's easy to put too much weight up front and crash down. You may also tend to struggle to balance your weight properly and have the ail of the board get hit by the wave to take off.
If the mast is all the way forward, you may get too much lift and not be bale to hold down the board on take-off and end up missing the wave. So you gotta find the sweet spot somewhere in the middle. Hydrofoil wing screws are the best way to resolve this especially if you will be swapping boards/foils/wings often. It lets you easily adjust your mast in the water and then find the sweet spot. Take note where that spot is. Your board may have markings, if not just use sharpie/whiteout/tape.
Awesome video with showing how the forces balance out. The BIGGEST thing people often forget is the tail. A tail/stabilizier can make or break your foil session. Fast wings needs fast tails. Front wings with tons of lift need a tail with tons of lift. Remember, your front wing wants to climb up in the water at speed while the tail is trying to dive down, effectively creating leverage on the mast to lift that board up. Experiment with different mast position, front wings, tails, shims, fuse length, etc.
Have fun!
Wing screws are a great way to dial in mast position! Once you get your spot figured you do you change them out for regular hardware for less drag when paddling/taking off/touching down or find that it's minimal?
One additional thing I forgot to add in the video is that positioning your foil a bit further back in the tracks than the balance point on your prone foil board can make your pop ups easier, especially if you are on a lower volume board. This lets you paddle in without worrying about getting too much lift from the foil as soon as you catch the wave and overfoiling. Once you've dialed in your pop up technique, and moved on to smaller foils this is easier to control and having the lift coming from the correct position will actually make your setup more efficient at catching waves at the cost of being a bit more difficult to control during the pop up.
On the other hand placing the foil too far forward can making prone foiling extremely frustrating and dangerous for beginners who can't control the sudden increase in lift.
Makes so much sense
Thanks @@henryhester1897 !
If I switch to carbon and thereby reduce mass behind the center of balance, I must move the mast forward in the track to put additional board mass behind the center of balance. Thanks for these invaluable videos. Wingfoiling is the most difficult endeavor I’ve attempted other than flying a helicopter. They are very similar in their simultaneous requirement of somatic ‘feel’ and intellectual understanding of the physics. With wingfoiling, the physics insights are underrepresented on YT
Thanks @jsibleytube! For me, having an understanding of the physics really helps my progression. Everybody learns differently though, so very glad to hear our videos have been helpful to you.
The best explanation I have seen, thanks 🙏
Ty for this theory video ! Im a wingfoil instructor and a loooooooot of people ask me where i put the foil, and i showed them this lift technique, now i understand more in details!
But as u explained i recommanded to them to move them foil a bit the foil back cause lot of beginners cant handle the lift
Carbon mast lighter = move the foil foward
Stoked to be able to add some theory to your lesson plan @vabrial!
Correct on the answer! All else being equal, a lighter foil will be balanced when it is further forward in the tracks than a heavier foil.
Excellent explanation
thanks!
Awesome video! The most informational about mast placement!
thanks Jack!
Simple, yet brilliant!
Thanks Shaun!
I find every board has a specific foot position based on volume distribution front to rear. So when you find that when you go to stand up then that is what you use as a reference to where your mast will go. But I have been using the lift the system with your finger method to get a starting point
That's a great point Scott and something I should have addressed in the video. The center of buoyancy of a foil + board will generally be a bit further forward than the center of mass of the foil +board due to the higher density of the foil vs board and increased mass in the rear of the board to reinforcing the tracks, deck, leash plug, etc. I prefer to align the foil's lift with the center of mass of the system for the reasons mentioned in the video, suppose this means I would need to shift my weight a bit further forward when moving slow on a high volume shorter board but I think the tradeoff would be worth it to have balanced flight characteristics. I'm generally on sinkers or longer shapes so haven't really played around with this too much so can't say 100% though.
I initially balanced the center of my foil on my fist to choose a mast position (board hangs flat) as you describe. But I noticed as soon as I got onto foil, I had to jump back a couple inches. My buoyancy was forward of my center of foil lift. For those of us on body weight plus ~10-20kg boards, I found it better to center the lift of the foils with the buoyancy. That meant further forward, which was also a lot more fun. My experience with gybes is that my speed through the gybe changes dramatically with wind conditions and 'arc', so learning to compensate for too much or too little lift needed to become a muscle memory - it was different all the time, but now I rarely notice it.
I agree. Start with foot placement relative to buoyancy then position foil mast.
The explanation of forces in this video doesn't make sense to me and I have a pretty good physics background (see my other comment)
I prefer to base mast position based on center buoyancy because Im a beginner and I dont want to move my feet once up on foil. Otherwise all points about forces and stable flight are spot on. In a perfect world, the center of boyancy would be closer to the center of mass.
@@NeuralEngin33rI think you’re spot on. I find that I need much less wind energy to get up if the foil is in the correct place relative to the bouyancy of the board
Well said Greg
thanks guys!
I've watched several videos proclaiming the same technique, and always thought it was somewhat simplistic, but until you responded to someone saying that the technique balances mass "while foiling" and you can make adjustments in the transition from taxi to foiling that I realized the genius of the technique. I had always thought the latter was key (you wanted same foot position for taxi and foiling). But thinking about it, your mass is heavier when turning, also lighter when being lifted by the wing in a gust. Basing the positioning so that the balance point is indifferent to body mass seems like the right idea after all.
Is the board speed a consideration at all? We sail at all different speeds all the time, but there is an average "crusing speed" for a lot of us. When going faster versus slower, is the center of lift of the foil actually different (involving shifting feet) or are we just tilting the board flatter to keep from breaching?
Great question David. It is indeed a very simpe technique to solve a rather complicated problem. Just so happens to be my favorite type of solution!
My thinking on the matter has evolved since making this video but most of it still holds true.
I think for early beginners it is important to balance the centre of bouyancy with the centre of lift so that they don't need to move their feet when transitioning from taxiing to take-off. However, as one progresses (and as you pointed out) it is more important to have the mass of the system balanced over the centre of lift. This often means placing the foil slightly further forward. A key time this is noticed is during pumping. If the foils is further forward the nose will have a tendency to pitch up during the unweighting phase of the pump and conversely if it is too far back it will pitch down. Since keeping the board "flatter" during pumping is desirable this is another factor to consider. Having the nose pitch up gently during the pump is nice though since it makes it easier to maintain altitude so for this reason I've been putting my foil a touch more forward recently, better to err this way since pitching down during the unweighting of the pump is counterproductive.
Your question about the centre of lift moving with speed is a good question but also tough to answer fully. One should think about angle of attack and speed as synonymous when it comes to foiling. Since lift is fixed the two are directly related.
The centre of lift moves with speed/angle of the foil but more or less depending on the wing design (planform, section, twist, etc). The other factor is that most brands do not have their tails perfectly tuned to balance the pitching moment and drag moment created by the foil. So a lot of the reason people are moving their weight/feet around at different speeds is not so much to deal with the moving centre of lift but rather the changing moment on the foil which is the sum of the drag moment and pitching moments of both wings.
Would love a deep dive follow up video! In earlier comments buoyancy was mentioned and I think this is one point that could be explored more. To me Kane de Wilde’s trick of balancing it - out of the water - will *always* result in mast being too far back. When riding on foil, the foil, fuse, stab and part of the mast are under water and consequently not as heavy as in air. Therefore we must consider the center of mass of the system while flying through water. I wonder if there is a good rule of thumb for adjusting Kane’s rule of thumb. 😉😄
@bcransto1 agreed there is two ways to look at balance, when the board is on the water vs when the board is flying. In my option, the first case is really just about aligning the net result of the centre of buoyancy + centre of gravity with the centre of lift so that the riders weight distribution does not need to change at takeoff. This video is focusing on the second which is the ideal position when riding and assuming the user will make the necessary adjustments during takeoff to have a more balanced ride. Good design can bring these aspects together but of course is not the only concern so must be weighed against other factors. In a poorly designed board they could be way out in which case the rider would need to choose one or perhaps compromise in between. Gets complicated fast, I really like your suggestion of a deep dive follow up though so will start thinking of ways to simplify it for a video :)
Super informative
thanks Todd!
It is very insightful. I never think of it. Thanks for your sharing.
Originally, I thought moving mast forward can be compensated by moving body forward. But actually it is more complicated than that. Thanks
Thanks Lawrence, that does work but as you say it's more complicated especially when taken to extremes. The biggest time I notice the imbalance now is actually when pumping, changing feet, or dropping down a wave rather than turning which I described in the video. Need to work on a follow up as another couple commenters have mentioned!
One thing I used to do was set the board and foil upright on the sand as if you were riding it and if the board fell forward, move the mast forward until it could stand upright by itself. Nice video again!! 🤙🏼
that's an interesting trick too! I suppose you want it balanced so the board barely avoids tipping forward?
‘Used to? ‘ Was it a flawed idea then?
Really helpful as I’m just moving from slogging to flying
Thanks Henry! Such an amazing journey and progression
👍🏼Great video / explanation. With a lighter Mast for my understanding you have to move the mast little back to compensate the stronger (same) lift force - correct
Thanks Mike! With a lighter mast you indeed want to move it back since the reduced weight at the back end would make the system front heavy so the mast is moved back to compensate :)
@@omenfoils 👍🏼
Congratulations. Many thanx. I'm impressed by the quality of your video, this is so clear and smart. May be useful to better explain the fact that when we turn, the board "becomes heavier" because of the centripetal acceleration. One question: if I keep my foil the same, but changing only the front wing, I have to move the position of my mast practically, to maintain a good balance when riding (E.g. replacing a 1300cm2 front wing by a 900cm2 front wing --> I've to move my mast backward). Looking at your video, only focusing on the weight of the foil & board, I do not see how to explain the fact that I need to move my foil forward or backward depending on the surface/shape of the front wing.
Thanks @Louardoul, you're right on a better explanation being needed on the board getting "heavier" being required. I didn't want to confuse things too much by going down a rabbit hole in the video but will try to find a better compromise in the future between skipping over something and going too deep in the weeds!
I responded to a similar comment below with this explanation:
Hi @gwendal5620, really appreciate your comment. I'm sure there are lots of other folks out there with the same question so I'll try to provide more context.
The board getting "heavier" can be thought of in the same way as that the old trick to keep water inside an upside-down bucket by spinning it aggressively overhead with your arm outstretched. The change in direction of the bucket is constantly accelerating the water towards your shoulder so the water seems to constantly "pull outwards" on your arm. You can even feel the same during hard turns on your foil since you'll notice your legs are under more force (your body weighs more because of the angular acceleration). The same extra force that is making your body heavier is also making your board heavier and will cause it to pitch nose down if the foil is too far back or nose up if the foil is too far forward.
Here's a good link if you're interested in the physics of centripetal acceleration: courses.lumenlearning.com/suny-physics/chapter/6-2-centripetal-acceleration/
Regarding your question on changing the front wing there are two reasons why you’ll want to reassess your track position:
The center of lift of the new wing could be further forward or backwards from the old wing.
The weight of the new wing could be different (less significant)
Interestingly, changing the stab or even the shim/fuselage length will also require an adjustment to track position to achieve a perfectly balanced setup. Even though the center of lift of the front wing is unchanged changing the lift from the stabilizer will result in a change to the location of the center of lift for the whole foil as a system.
To make matters even more confusing the center of lift actually moves with speed! This can be mitigated by good wing design, but it’s ultimately why the best way to tune is to get out and ride at your preferred speed and throw some hard turns and feel if your board is pitching up or down. The upside down balance trick is super helpful to get close but never intended to be a 100% solution.
Hope this is helpful for your riding and understanding of the dynamics! Tuning can be a never ending process, but like many things most of the benefits are had by getting it 90% of the way there. Can be a lot of fun to tweak gear and see the results in your riding, with our equipment we’ve gone to great lengths to make tuning easy and intuitive so riders can access the top performance of our gear and focus on their progression.
@@omenfoils Many thanx for your time and your clear explanations. Means that the center of lift can vary a lot between different wings, amazing.
Happy to@@Louardoul , thanks for the great question - I'm sure there are many others wondering the same! Centre of lift can vary between wings and since the distance of the wing from the mast has a big affect on feel, different wings are placed at varying distances from the mast.
such good videos! thanks greg!
Interesting video. In your exercise with the arrows, why isn't there a downward arrow above the stabilizer? Isn't that one of the primary purposes of the stabilizer? I guess it's possible for a stabilizer to have neutral lift (or even positive in the canard case). But, I think, most stabilizers have negative lift -- specifically to counterbalance the weight of the board that is in front of the main wing. Is that not true?
This is very true David! I'm summing up the forces though for the sake of simplicity. The downward force of the stabilizer is relatively small compared to the lift from the front wing, but more importantly, there is a rotational moment created by both wings and drag from the system moving through the water.
These are the forces that are counteracted by the downward force of the stabilizer acting on the centre of gravity of the system along the axis of travel by the length of the fuselage. Breaking down this stabilizing force into this counteracting moment, the downward component effectively reduces the total lifting force of the front wing but does not "move" the vector's horizontal position assuming the lift is aligned with the centre of gravity of the system. This is because the moment created from transposing the downward force from the stabilizer to the centre of mass is balanced by the other forces mentioned which would otherwise cause rotation.
Sorry for the long answer to a simple question! I break down these forces more in our stabilizer video if you're interested in more.
I didn't understand why things change when we turn. I agree about the increase in lift of the front wing, but why does this increase in lift cause the board to dive if the foil is at the back? During a turn, the weight of the board's center of gravity remains in the same position with the same intensity, so proportionally it is weaker compared to the lift of the foil, so the board should pitch up ?
Thank you for the tip about balancing the board upside down.
Hi @gwendal5620, really appreciate your comment. I'm sure there are lots of other folks out there with the same question so I'll try to provide more context.
The board getting "heavier" can be thought of in the same way as that the old trick to keep water inside an upside-down bucket by spinning it aggressively overhead with your arm outstretched. The change in direction of the bucket is constantly accelerating the water towards your shoulder so the water seems to constantly "pull outwards" on your arm. You can even feel the same during hard turns on your foil since you'll notice your legs are under more force (your body weighs more because of the angular acceleration). The same extra force that is making your body heavier is also making your board heavier and will cause it to pitch nose down if the foil is too far back or nose up if the foil is too far forward.
Here's a good link if you're interested in the physics of centripetal acceleration: courses.lumenlearning.com/suny-physics/chapter/6-2-centripetal-acceleration/
an awesome explanation, thank you 👏
Thanks Hugo!
1. If the board has rocker in tail, sure the posistion is very important, but as no rocker design I think the better is get good filling in stand and foot pressure. 2. Flip the board to find the gravity center is trick especially use the palm of hand ----you cannot use the finger to make the correct result due to your finger cannot take the weight, but you wide palm will make it wrong especailly the wing has convex curve on top, just little tune the palm will tilt the system. A better idea would be to tie a string to the board and check the system's balance.
Thanks for your comment Bruce, I'm not quite sure what you mean on point #1.
Regarding lifting with the finger, I form my hand into a "knife" and lift with my index finger/knuckle which is supported by my other fingers. Found this works pretty well.
great content. But if i want to easier in the dock start, should i put it further back or forward?
Thanks!
Perfectly balanced will be easiest since the board will fly straight even without your body weight on it will be easiest for the run up and jumping on. Running with the foil a bit further forward than balanced will bring the nose up "automatically" when you unweight which is nice but you need to be more conscious to drop the angle of the board before loading the pump or you will loose a lot of efficiency.
Most really small dockstart boards end up with the centre of lift ahead of the centre of gravity based on the small size and limited track placement.
Congrats Greg - excellent video.
Thank you.
What do you think about the rake of the mast. I’m playing with it for a little while now and I would love to have your opinion on how it would affect riding position and performance.
🤙
Thanks Giovanni! Rake is a very interesting and often ignored factor of the mast, stoked you are taking an interest in it! Rake can make turning response more "uniform" through the water column since as the mast is submerged deeper it it's centre is located closer to the centre of turning of the system. This mitigates the feeling of the foil being "too loose" when close to the surface and "too tight" when deeper. The downside of rake is that it affectively increases the chord and length of the submerged mast when the angle of attack of the foil is at around neutral or greater. This means that it increases mast drag at higher speeds while decreasing it at lower speeds. For these reasons Omen using only a very slight rake in our masts.
Best description I’ve ever come across.
Finally understand.
Thank you.
Please keep
This content coming.
So easy to understand ❤
Thanks @ImpossibleOne! Really appreciate the positive feedback!
Great video, Greg. I actually had a lightbulb moment a week ago when i realised i had been using too small of a tail (KD13R)/not enough shim with my 170 progression. It had kind of evolved that way starting with a long fuse then switching to a medium without changing tail or shim because i was using the 170 in overpowered conditions a bit, trying to reduce front foot pressure on bigger bumps..only now realised i was loosing the upward momentum for turns/having a tendency to nosedive in turns..Also, i got so used to it that i didn't question my tuning, but kept wondering why i didn't feel small waves and had some problems pumping..at first i put it to my shitty technique but finally tried more shim..just swichting from 0.5 to 1.0 deg made a huge difference.. Next will be a bigger stab. Regarding mast position, when winging you also have to consider your foot position has to stay balanced with the centre of buyancy/volume to avoid nose/tail diving. Hopefully your straps and masttrack are designed balanced in that way, i had a board where it wasn't so i had to start further fwd and then move feet back..sold it after a while..
Awesome, always nice to have those breakthrough moments! And figuring it out the hard way means you'll never forget it! Will be doing another video on tail wing tuning but spoiler is I like to go up to max speed and have the tail adjusted to be stable in this position (if board feels nose down pitchy add more shim or use a larger tail and vice versa with board feeling nose up pitchy).
Totally agree with your point on balancing the buoyancy with foot placement, unfortunately this is up to the designer and is often overlooked in our quickly evolving sport. As the user can't do much to change it other than what you did!
cheers!
@@omenfoils Thanks Greg this is interesting, looking fwd to that video. Will check trim at top speed next time out. I guess trim at wing powered top speed will be slightly different than wave powered due to the added forces of the wave. The added speed will add lift and change pitching moment depending on foil and stab tuning in both cases. But i should think depending on your position on the wave the circular wave motion might add or subtract pitching moment. Also, the locked in feeling racing down a wave overpowered might be either too much front foot pressure or not enough which creates a negative moment against the turn direction. Kind of a fine line to tune if the foil wasn't designed for that conditions. Reminds me of setting back your snowboard bindings for powder on a non long powder nose shape but then having too much edge in front on slopes..
Great discussion@@andiabel212 , there are definitely lots of subtleties difficult to go into detail over in text. I believe winging and surf tuning should be the same except for niche cases. The foil experiences the wave motion as additional "lift" when riding or rather a change in the freestream velocity. Ultimately in either case the stabilizer counteracts the pitching moment created by the wing but more importantly in my opinion the drag from the foil which has quite a bit of leverage relative to the "control centre" pilot. Very extreme moment compared to any other examples of flight that I am aware of.
Center of bouyancy can also have an effect on the equation when trying to take off.
This is board specific.
Totally agree Nick!
Great video! Did you do an Aluula interview with us 4 years ago? Your voice sounds familiar.
I did indeed, we'll have to do a follow up sometime!
Great video explaination! I can’t wait for my next session to test some. I’ve been having trouble with my experiments, changing lots of things in short succession. This should help me a lot. I ride an inflatable 105 L with a carbon setup. So far I find the mast way back and a small +0.5* shim seems to work well. I’m fine on level flight and can turn OK, struggling with foot swap with too much up pressure on the front foot.
Your description of turning dynamics should really help me correct! Thank again!
happy to help Maury! If you feel a lot of pressure on your front foot when going fast having a bit less tail shim will help reduce that. Usually front foot pressure is helpful in foot switches though - are you leaving your front foot on until it is replaced by your former back foot before stepping back?
I think there is too much front foot pressure. The reaction when I lift it is too great. My 0.5 shim should reduce lift.
I do best when I jump switch feet. Shouldn’t I be able to step switch?
I do fine at everything else. Flying level, carving Ss, even toeside riding is coming along. I’m just stumped on the foot switch.
@@mauryjacob5363 stabilizer shimming is a complicated topic which I'll be doing a breakdown on in the next few weeks. If you feel too much front foot pressure you could try standing further forward or reducing the angle of attack of the stabilizer (shimming the front of it UP or rather trailing DOWN).
I'd really recommend the step switch since it is so much more consistent. Jump switch I think of as more of a "trick" fun to play with but not a "go-to" if you are looking to get on a wave quickly.
Try bringing your feet very close together so they are nearly centred over the lift of the foil, also keep your front foot pointed quite far forward so there is room to move your back foot beside it.
As soon as your back foot touches down to the new forward position immediately send your old front foot backwards. If you have the wing more overhead at this time and pull in for some extra lift it makes it even easier.
Hope this helps!
All good topics. Yesterday I tested your mid-chord hang suggestion to balance the board weight over the foil. The back of the mast read at 10 cm mark when the board picked up level. That is a full 13 cm forward of where I was riding with the mast all the way back. That is where my feet find the strap positions pretty comfortably in flight. I ride smoothly there but as I said the front foot seems too heavy. The nose rises fast when I lift it.
I wonder if the super lightweight nose on my iFly 105 inflatable affects that weight balance point?
I am awaiting wind to test ride in that forward position. I will be surprised if it doesn’t porpoise on liftoff.
@@mauryjacob5363 I think you may just need to stand further forward. Looking forward to hearing how it feels when turning too!
Great videos on this subject Greg!
Got a question for you:
When winging in a straight line standing centred on top of the board and performing no other special action(s) I constantly have the feeling the board wants to "dive" (go down with the nose).
I have tried to move the mast further forward, but that didn't change this feeling, I just had to stand a bit forward to compensate for that.
I also tried to achieve the same by changing the angle of the stabiliser (I had it in neutral (not shimmed) initially), but it also didn't change anything on that "dive" feeling.
And in the end I liked it most in the neutral position anyway.
The strange thing is, that when I ride down a wave and hold the wing by the handle, the whole combination really performs well and the diving feeling totally disappears...???
Any ideas what's happening here? Any recommendations?
Thanks Ron! To answer your question it would be really helpful if you could try this during your next session and report back:
Stand and ride around on your board as normal and ride around to confirm you're comfortable. Ride at a medium/slow pace and note where if the board has this tendency, increase your speed to medium fast and pay attention to the same, finally go as fast as you can and see how the feeling is changed. Don't move your feet at all through this process, once we know how the foot pressure/nose down dive feeling is changing relative to speed we can diagnose what is wrong with your tuning.
Looking forward to hearing back!
Greg
Dear Greg @omenfoils
I just tried out your suggestion:
When going slow, there's a slight raising tendency (nose up feeling) that I need to compensate by giving more front foot pressure. So I'm gliding above the water but don't have the board level with the water surface (nose up a bit).
After a while, I manage to level out the board after which the board accelerates and reaches a medium speed. I now stand balanced over 2 feet, but I feel the constant diving tendency (nose down). Additionally I can say that this is the position and speed I'm in like 90% of the time.
When I push to go to higher speeds, I can keep the board level with the water surface standing balanced over my 2 feet. However it feels like I'm on a bumpy road (in the up and down sense). Not stable at all and I have to correct constantly.
By the way: All the above with my feet in the same stance/position.
Does that make sense?
@@RonKolijn Totally makes sense Ron. Track position won't help this unfortunately. You either need a larger stabilizer, more angle of attack on your current stab, or a longer fuselage if you have one. I'd try shimming the stab first, make sure you are shimming the leading edge "downwards" relative to the direction of flight (ie. not down when your foil is flipped over and you are working on it). Start by adding 2.0 degrees, then try 1.5, 1.0, and 0.5. Choose the shim that provides most even foot pressure at high speed.
Riding will feel more secure if you err on the side of a bit extra front foot pressure (more shim) but you'll get a touch more glide and low end by going the other way. Most folks are better off with a bit extra front foot pressure.
Please let me know how it goes!
Greg
@@omenfoils
Dear Greg, I had an 'early-bird' session here in Holland this morning, as I was eager to try your suggestion(s)
This morning I have put my stabiliser to the maximum angle (I own an AK Foil, that works slightly different, but the effect is the same as shimming)
And guess what; the 'nosedive-feeling' totally disappeared! On max-speed in a straight line, it's still a bit bumpy, but far less than before, very well manageable.
I really didn't expect this, as I thought it would slow down my foil and give me too much front-foot pressure, but no, all fine!
This video and the one on tail wing shimming have made a lot of things more clear to me and certainly have helped me. And to top it off, your personal recommendation was the cherry on the pie. Big thanks to you Greg!!!
@@RonKolijn Right on Ron, very happy to hear it! Thanks for popping back in to share.
This early in the sport there is still lots of misinformation and equipment available that does not work well out of the box - certainly serves to make things more interesting though!
Try reducing the angle of the shim bit by bit to get a touch more performance, and let me know if you'd like to get your hands on some Omen gear :)
nice vid Greg! really well said and explained.
thanks @OCEANBOUND1!
Nice clear explanation. I have a question. My and my girlfriend share equipment. If she rides with the foil placed where I use it she needs to stand too much forward, so I usually move to mast back when she's riding. She is 20kg lighter than me. Axis HPS830 (circa1000cm2)
Interesting, do you find when riding with the mast further forward in the tracks that you have to apply more front foot pressure when turning hard?
great video
Thanks Oscar!
I think the mast is behind the center of mass of the board+foil assembly, so making it lighter would move the center of mass of the assembly forward, so to keep the system balanced would you also have to move the foil forward in the tracks?
Exactly right @nathanielmorbey! All else being equal, a lighter foil will be balanced when it is further forward in the tracks than a heavier foil. Interestingly this works the opposite boards, with a lighter board you actually have to move the foil further back in the tracks. The phenomena explains why foil positions are moving more and more towards the forward as board size increases and in the extreme case of 8' downwind boards almost in the middle.
Greg, I'm 74 years old and probably too new to the sport to ask this question but... My long active life has given me some persistent right knee (back foot) pain after an hour of regular stance riding. I try to switch to goofy but on a good day the riding is %80-20. Would you suggest a track position that can lighten the back-foot loading? I read on forums of riders who never switch feet and this leaves me confused. Note: I still crash during foot-switching
Hey Kip, the easiest way to lighten the back foot loading is actaully just to stand further back on your board. If your foil is already in a balanced position you should keep it as is, but standing further back relative to the foil will put more pressure on your front leg.
Have you checked out our most recent foot switch video? I definitely agree foot switching is incredibly important for keeping the body healthy if you're winging a lot!
totally agree but it depend how is the size from foil because the lift from the frontwing changes if is a 850 or 2400.... im right or not? nice video
Thanks @Elninosurfcenter! This is an interesting point and something I think is very often misunderstood.
All else being equal, a larger foil has the potential to create more lift, however all this means in reality is that it will get you up on foil at a lower speed.
Any foil you are riding at steady state is providing the exact same amount of lift (your bodyweight + board + foil - weight of water displaced by submerged foil). Any more lift than this and you will be rising, and any less lift and you will be falling. To create this amount of lift it is the speed and angle of attack of the foil that change. I'm not sure if I have explained this concept well, please let me know!
@@omenfoilsi have 4foils that have area of around 1000 (axis bsc, hps, art and spitfire) i put them in different position as they have more or less lift.
What is the best was to find the center of lift of the foil wing?
Hi @surfdocsteve, center of lift isn't easy to pinpoint since it's affected by multiple things like foil shape, sweep and actually even moves around with angle of attack/foil speed. Additionally, the center of lift of the foil as a whole is effected by the downforce of the tail which changes significantly with angle of attack too!
So ultimately, I think the only way to really dial in a setup is to get a good approximation, then ride and adjust based on feel. The important part is to perform hard turns and see which way your board is pitching and make micro-adjustments accordingly.
Sorry for somewhat avoiding your question!
@omenfoils in the video you suggest using the middle of the chord length. Seems like a good rule of thumb, and then fine tune from there.
I'd seen this technique in another video, but Thanks for great explanation, it helps alot to validate the approach.
Hi Greg, very clear and profound explaining, just like in your other videos!
Even though you are technically right, I think this explanation doesn’t quite hit the nail on the head though. Even though the boards center of weight has a bigger leverage onto the center of lift, there is still the rider on it, who has less leverage but a substantially higher weight. I would assume compared to the riders effect onto the center of lift, the board's impact is rather unsubstantial.
And then in a turn we do not pull 8g like a fighter jet. I would assume around 2g in a very tight and snappy turn.
So for the average rider, wo doesn’t do that kind of supertight turns, I think it’s much more important, to have the mast positioned in a way that it aligns with the board floating neutrally, like someone commented before.
This way, when you transition from the water into flight, no weight shift is needed.
I partially also disagree on the recommendation for beginners. It may be useful for the absolute first timer to not get the foil flying in any way before he/she gets familiar with board and wing handling.
After that I recommend to put the mast to position about in the middle of the track (depending on foil and rider weight obviously), to get a feel for the foil lifting. With the mast all the way to the back it’s hard to even feel the foil flying an when you move back all the way on the board you will lose all the speed because this will sink the tail.
Just my thoughts, I appreciate any discussion and keep up the great work!
Cheers
There is something missing on the physics side to explain the phenomena, will keep working on it for a follow up video! Track position is of course a personal choice, my recommendation for intermediate and above riders is to optimize for turning and hopefully choose a board that is well balanced in buoyancy in this position. If this is not the case I still think it is better to have to adjust your feet after a start than compromise on every turn but of course there is no right answer on that just preference.
I agree on your recommendation for beginners, I had meant to say that as soon as they are able to get on foil to adjust the foil to the proper position.
"Middle" of the box can be difficult since various foil and board manufacturers all have different track positioning and distances from front wing to mast plate, foil weight, etc.
Thanks for the engagement - great to have discussions like this with other passionate foilers!
I started winging a 6’9 KT Dragonfly recently (love it), with Takuma 1095/1440 and Lift 170. Currently I feel like I have to put all foils at the very back of the tracks, but this might change with more sessions. I tried the balance method in this video and there’s no track position where the board is even close to balanced. :D I suppose you’re saying that this means the board will become fore-aft unbalanced in hard carves?
Hi @mirzapirza, does the board tip nose down or nose up when you try the balance trick?
But yes, ultimately if the track placement does not allow the centre of lift to be aligned with the centre of gravity of the system you will have to shift your weight progressively more the harder you turn in order to compensate unfortunately. It is something people get used to, it's just easier when everything is aligned, feels more intuitive and controlled, and lets you be more aggressive.
@@omenfoils it tips nose up (tested with the Lift). I wonder if other boards with the tracks this far forward are balanced?
Hi@@mirzapirza , if it tips nose up when balanced then I agree that means the foil is likely positioned too far forward to be ideally balanced in turns.
One point to note is as board length increases the tracks appear to move further forward (when viewed relative to the tail). However, if they are staying the same distance from the board's center of gravity they are actually not "further forward" at all. The distance from the tail is an easy reference point but not very relevant based on all the different board shapes, lengths, and weight distributions. Unfortunately it has become the industry standard since it is easy to measure and visualize.
Nice video. I will not be falling into that trap of what changing to an aluminum mast will do. 😀 I just ride them. I don’t understand them.
hahah, thanks @Hdip!
I was cleaning the kitchen and clicked, hoping for some nuanced insights on mast position. Whatever people are experiencing in turns with board dip is most likely not related to the mast position and the moment of the board being forward of the center of lift. (It always is on mine). The rider has a far greater effect on moment than the board can possibly have in any mast position
Thanks Ian, I don't disagree. I made a comment a few months ago that I need to film a follow up but it's probably buried. The pitch up/down of the board with an "off centre" foil position is created during unweighting and weighting the system rather than turning directly.
I would add though that while rider skill and input is the most important variable and good riders can adjust and compensate for "poorly" tuned systems or even reap benefits from certain tunings which would cause an intermediate rider to struggle.
Ultimately I'm trying to find to provide the most accurate advice for folks to best understand and improve their equipment but at the end of the day the best way to improve at foiling is foiling more :)
I seem to be the only one but this doesn't make sense to me! You combine together the forces from each foot into one force and then the weight of the foil/board into another. But you leave out combining the riders weight and board/foil weight to create another single force. Ultimately it's the position of the force from the combined board/foil/rider weight versus the lift from the front wing (ignoring any stabiliser effects) that affects the balance of the foil.
In level flight the centre of gravity of the board/foil/rider will be in the right place to balance the lift from the front wing. As you say, the downforce during the turn will increase but that applies to the total board/foil/rider system. It won't cause the combined downwards force to change position.
If it was balanced going into the turn, then it wouldn't get out of balance during the turn. You say the extra leverage from the board weight out in front is significant but ignore the corresponding increase in the riders weight behind the wing creating a counteracting torque.
In setting up the board I would follow these steps:
1) Place the footstraps relative to the bouyancy of the board so that I can comfortable stand in them when stationary and pump the board up onto the foil when starting
2) Position the foil mast to get balanced foot pressure when foiling
@oldboywindsurfer, you're right on the money with the explanation lacking. There is an imbalance in the forces during the turn by definition. During a turn the wing is in roll and a portion of what was the lifting force points towards the center of the turn. This force needs to exceed the enertia of the system in order to maintain the direction change. This sets up a rather complicated 3D system of forces which results in the phenomena of nose down pitch for a foil position too far back and nose up for too far forward. My explanation is oversimplified to the point of being flawed but the phenomena it describes and corrective measures make a big difference to performance. Will work on a better one when time and resources align - still trying to figure out how to explain and show the concept. My animation team is made up of a pair of Crayola scissors and printer low on toner, so 3D visualization are bit out of scope at this time!
That being said I strongly believe that for any intermediate to advanced foiler the most important aspect of track placement is to achieve balance in turns. I agree for some board designs this could mean you have to adjust your feet after water starting which is not ideal, but ultimately what part of the foiling experience are you trying to optimize? :)
Nice video, i think having a lighter carbon mast or a lighter mast will put more pressure on the front wing and you will have probably to move your foil a little more to the back.
Ps: apparently im wrong i checked your answer bellow 😂 anyway the more plug and play foil i got and the more happy iam i got the perfect combo at the moment no shim nothing, i had a armstrong previously and it was a nightmare to fly , i never found the right setting with it end up selling the whole quiver of foil after 6 month.
Haha, yeah I chose that setup because it does seem a bit counter intuitive.
We strive to make our gear as easy as possible and provide specific tuning advice to ensure customers can "set it and forget it" to focus on riding :)