@@casey6556 It can work on those trucks too... technically... assuming you could generate enough downforce to fully compress the shock absorbers in the truck's suspension...
That's very similar to how Formula race cars have to drive fast enough to generate enough down-force to keep them stuck to the road around corners. If they don't drive fast enough, they'll skid off the road.
Holy crap, just built a 1 billion $ boat, put the last touch of paint on it then drive it at full speed toward a bridge with a physicist telling you not to worry, it will sink down in the water due to Bernoulli’s principle. Thats a butt clenching moment if ever I heard of one.
Being a Captain and active in the Maritime Industry for more than 20 years, all I can say is that your videos should be teaching material. Congratulations!
I have used the effect to my advantage but did not know what it was called, I agree these are very educational because I only heard mention of, what we called, pressure effect once during my maritime studies. A captain, later harbour master and then lecturer talked of a US aircraft carrier approaching the east coast of Australia crossed the continental shelf into shallower water but still deep by any standard but she squatted and flooded through open portals aft and several sailors perished but the portals were 10m above waterline. So at speed , the depth changed from about 2000m to 250m, interesting story.
I'm sorry captain! I'm giving you all she's got. I can give you no more! The engines are already at 120% capacity. I do not know how much longer she can take.
I lived here during that event. I LOVED the anecdotal interviews following: Nervous passenger to the Captain, "Captain, should we abandon the ship?" Captain, "My dear, we are already on the bottom! Go back and have another glass of Champaign!"
@LeDerpLegend We're just sharing knowledge here. It's not "lol how stupid are you, it's spelled champagne", it's "thank you for sharing, by the way the correct spelling is champagne - common mistake, just thought I'd let you know"
@@MisterLongShot_Official yeah its often said that air is a fluid. engineers i have met take that saying literally and would probably win in any argument
@@efthymis_mc34 both, the ground effect of a car, the ground effect of a low flying plane and the squat of a ship are all caused by Bernoulli's principle
@@boldCactuslad "its often said that air is a fluid" FWIW, By definition, gases and liquids are fluids. Fluids flow. In everyday language we tend to use fluid to describe liquids more than we use it to describe gases. In scientific and industrial communications a fluid is just as likely to refer to a gas as refer to a liquid.
A tiny correction is that Oasis of the Seas didn't squat under a bridge over a river, but rather over the Great Belt strait in Denmark. She has telescoping funnels, and would have cleared the bridge by about a foot, but she barrelled at it at 23 knots, and thus gained another foot from squat. Still, 2 feet of clearance at 23 knots in a brand new ship, biggest in the world, under one of the most heavily trafficked car + train bridges in Europe, that must be a proper pucker event..
you have no idea how happy your correct explanation of Bernoulli's principle at 2:49 made me :D The fact that you said it occurs simultaneously and not one casues the other made me very happy indeed :D
There's so much important information in this one (again), i hope every skipper cruising through a canal knows this stuff... I can picture many situations where people overreact or simply react wrong due to not knowing the physics behind what's happening... oh boy. Thanks !
As a pilot (air, not sea) these sorts of videos are incredibly interesting to see the similarities in air versus water behavior. Thank you for such great content.
I agree. I sailed on this ship from New York to Southampton. The departure was at full speed because she was outrunning a hurricane. We had a chart up showing where the Titanic sank. We got very close to the spot. It was quite emotional.
I thought I had everybody on my side. But I went and blew it all sky high. And now she won’t even spare a passing glance. All just because I ripped my pants.
We experience exactly the same thing on our deep drafted narrowboat. Some of the UK canals are quite shallow in places you can be flat out and only be doing half the speed. also you can see the squat as the boat noticably sits lower in the water. we also experience bank effect and have also practiced the Texas chicken, works a treat if the other boater knows about it also, most don't though. Great explanation. I'm surprised the captain chose to go over such a shallow area when deep water was closeby.
Same thing in the aviation industry. While planning a flight plan, we always used to plan the minimum flight level above the highest point the aircraft in question would fly over during the flight.
I was Mate this day on a nearby Sea-Land containership as we transited offshore from Boston to New York harbor and heard the VHF traffic on the air. Next day after we docked in Port Elizabeth NJ saw the story and interviews with passengers on TV.
Its so cool to see Bernoulli’s principle in use here sucking a ship downward, and also seeing it used in almost the same way to suck race cars closer to the ground to get more grip with ground effects. I love this stuff!
Ah, man, finally a video i can REALLY relate to! I've been working as a 1st mate on the shallow seas north of The Netherlands and we really had to work with this phenomenon. Excellent video!
Once again a video about something I never knew existed, around a subject I have minimal knowledge and information I doubt I will ever need to know but I am immensely happy that I now know it. Thank you, I love this channel.
Spot on with that one. Apart from having been a Master.Mariner, before I retired, I had wa bespoke Narrow Boat built for cruising the inland waterways. This boat was 62ft long and weighed approximately 22 tons when fully fuelled up and with water tanks full. Passengers along for the ride, used to comment about the way the water level in the canal appeared to drop as we passed at 4 knots, near the bank. A narrowboat is a flat bottomed craft and the effect you mentioned was very much in evidence - I explained that if If I was travelling over. A patch of water which was c shallower than normal, I would slow right down. To many, this seemed n improbable solution - indeed, I came across, & passed boats which had become grounded, simply because they thought that their speed would carry them over. How wrong they were!.
I love these videos! I am a software engineer at a company that does under keel clearnace modelling and I did not know anything about how ships work before starting. Your videos give me a much better understanding of what it is that we are modelling.
I can't say I expected to hear the words 'chicken' and 'squat' in relation to ships' behaviour , but these are perfect explanations. Obviously things could've gone worse with the _QE2_ , if she'd been sailing somewhere where she could've sunk, considering the damage, but I bet that's a lesson her bridge crew never forgot.
So what happens if your mega millions ship that doesn’t fit under the bridge suffers an engine failure before it gets to the bridge…..or a loss of steering? Loved this video, I remember people lambasting a couple of captains who hit the bridge…..Why didn’t he slow down? Well now we know. 😮
*"Oasis of the Seas"* was build in Turku, Finland, in 2009, and she had to sail through danish waters to get from the shipyard in the Baltic Sea to the Atlantic Ocean. She sailed via *Storebælt* - or The Great Belt, to Kattegat and onwards to the North Sea. Storebælt is not a river. The bridge she had to pass under was *Storebæltsbroen* - The Great Belt Bridge.
Really interested video. I just have one catch, for all of us non American feet are a bit weird. Maybe for next videos you could also says how much is in metric, or at least in the video labels add also the distance in metric
(Don't say this loudly, but in the UK, it depends on your age as to whether you understand feet and inches or not.... I remember being at primary school and Miss Broad, our teacher, introduced a new sort of ruler. It wasn't flat as we were used to, and it had lots of smaller divisions on it... She was introducing us to centimeters! This was back in, oh, 1971 or 2, I think. To this day I continue to be more comfortable using feet and inches when I'm measuring up for furniture, or sewing, for example, as it's what my Mum and Dad used at home... Maybe now England's left the EU we'll go back to good old feet and inches, pounds, shillings and pence, and ounces, pounds and stones... 😅 😂😂 🤣🤣🤣!)
"sir we don't have the clearance to leave port, I recommend we deconstruct some of the antennae to make it under the bridge" "Full steam ahead" "What?"
Watching your videos is always a pleasure. Im always looking forward to your next release. When i discovered your channel in the first place, i binged all your videos. Thank you so much for your excellent work!
I really enjoyed this video. Thank you for explaining all the various physics involved with speed and distance to the bottom of the sea floor. I had never thought the ship would squat like that in shallow water. Thank you for the content you have, it fills the hole that Modern Marvels left in my soul.
I would prefer these videos without background music, I find it hard to concentrate when there's music playing at the same time. Other than that great video as usual, I love the animations and clear explanations, keep up the good work!
Excellent video again. Basically this is a same effect as the ground effect of an F1 car, resulting in downforce. I assume that this effect is stronger in water than in air due to the differences in density between water and air. Consequently, in water you need less speed to generate this effect. And, of course, ships don't have a suspension to prevent bottoming out 🙂 Even though it sounds a bit counter-intuitively (maybe), at slow speeds, trapping water can also work as cushion. If you berth a large vessel against a closed quay wall, with little under keel clearance and a small berthing angle, the water cannot "escape" quickly enough and will become trapped between the hull and the quay wall, consequently absorbing some of the berthing energy due to compression. This is actually taken into account when designing the fender systems. The reason this works, is because of the low speed and therefor the lack of a low pressure area along the vessels hull.
Imagine being the captain who has to drive a newly built, largest of its kind, billion dollar ship at high speeds at a bridge that it doesn’t fit under relying solely on the fact that it’ll sink a few feet because science. That must be a fun situation to be in.
@@efthymis_mc34 don't give the engineers any funny ideas! Someone gona hire Herman Tilke to come in and design a route into a harbour now with a constantly changing sea bed floor to make ships porpoise
I only have a cabin cruiser but I never assume the charts are 100% accurate. The Great Lakes vary so much in depth You could be fine one year but in trouble the next year.
My Grandmas house was on the shore of Saginaw Bay. In the 60s you had to walk 1/4 mile to the waters edge. In the 80s it was right up to her door. Then a period of low water again. I'm out of state now but I hear the water is high again.
@terryboyer1342 I'm on south georgian bay (lake huron). Right now, the waters 2-3' lower than it was just 6 months ago. In 2021, it was around 5' higher than it should've been.
On top of that there’s been times where the change happens over a matter of days too, so one time you go up the water is high, you come back a few weeks later and it’s dropped substantially. Rarer but wild to see.
@@crinkly.love-stick Always wanted to visit your area and backpack in Bruce but it never worked out. My loss as it seems crazy beautiful from pictures.
I remember standing along the Columbia River when a Naval ship was running up river. I don’t know what the name of the vessel was but it was a destroyer, escort or a battle ship of some kind. Had large gun batteries forward and aft. Anyway since I don’t have the cool details I did notice as it was approaching the river level dropped a foot or two like the tide went out. This is a huge river that’s a mile wide where I was give or take. After it passed it was like the tide came in and the river level was 2 feet higher than it originally started. From my uneducated observation that in a river system the vessel had to be running in less water depth than any channel sounding since it was moving MASSIVE amounts of water just from its propeller wash. I’m sure other factors of displacement ect ect were part of the effect. I had never experienced that before. It was amazing to experience in person.
I use pressure effects ocean kayak fishing, there’s a spot right next to rocky walls/islands that more or less holds the boat in place near the rocks, it’s rare to actually hit the rocks at all even when the waves are leading right toward them. you can pretty much stay in the active fishing zone just off the rocks for hours with minimal corrections, you don’t have to worry about being constantly run aground, the pressure build up at the wall keeps you a few feet away. Common sense and conditions play a role of course, If they’re big waves actually breaking on the rocks, that’s a different story!
Surely then even if they didn't know about the boulders they would have known about the squat, and would have realised that they still wouldn't have managed to clear the area with 39' depth?
Once we had a similar issues with a hopper dredge that was damaged by a boulder in the channel while sailing over it during neap tide. After the hulk was repaired in dock we decided to check the squat of this vessel at 10Kts with an UKC of 3 meters . The squat at the stern turned out to be over a meter , the squat at the bow was less
Yes! Several years ago the thought "do ships experience ground effect?" popped into my head. I read into it and found the fascinating Oasis of the Seas example. Though my recollection was that she would have cleared the bridge anyway but the squat increased the safety factor. When this video started I shouted out to my monitor "It's ground effect?!", made me really happy to see I was right.
One correction: the bridge Oasis of the Sea had to fit under was not a river bridge but the Sorebaeltsbroen, which spans over the sea between Denmark and Sweden
Really interesting. I recall a news article about that ship being sped along it's way towards the bridge which was known to be too low. The reason was not communicated and this left interested parties unimpressed with the reckless path. Days passed without the vessel being seized , no captain arrested , and so on. Most of us think speed only raises a boat . A ship is not a boat however.
I now know the reasoning behind something that occurs on land. The 8'10 bridge has too many moving vans where the drivers are expecting squat and aren't traveling fast enough to get under the bridge ;) This is the first time that I've ever heard about squat in a boat. As a captain of a large cruise ship they should have been well aware. 10% is nothing like the squat of up to 8ft that you mentioned.
US Nautical charts datum is “mean low water” which is less conservative than British or Canadian Hydrographic charts which are based on “lowest low water.” This results in “negative tides” being more common in US tide tables than those just mentioned. It also makes it easier to over-estimate actual depths when navigating in shallow waters. Actual clearance = chart datum + height of tide - vessel draft. It is possible that the navigation officer saw the 39 foot datum but was sailing on a “negative tide” which made the actual depth less than chart datum, in addition to the reasons given in the video.
I was there that day - she was going north in the Vineyard Sound, and I, south. I didn't know what the ship was, but I knew she absolutely didn't belong there. She was way out of the channel to the west, and far too close to the Elizabeth Islands. At least I wouldn't have been there with anything that big. Anyway, she sure did stop suddenly.
You sure you've got your directions right? I wasn't there, but everything I read and saw indicated she was sailing basically West by Southwest at the time, with Cuttyhunk on her starboard side (to the North). She was not travelling East or Northeast (or North as you have it). Also, and I could be mistaken, but I understood that she had made this exact passage on previous occasions.
Your videos are so interesting and so clearly explained, and it's very pleasing to learn about the physics involved in ships and boats and seas and canals etc. I'm all for life long learning, and you're a good teacher 😊 so thanks!
The description of the squat effect involving Bernoulli's principle in the video is very good, however taken together with the 2-D animation on screen at the time, people may arrive at a slightly inaccurate idea about why the water under the hull must speed up in the first place. I completely understand that this style of animation is usual for the channel, but for anyone who wants to have a fuller picture it may help to think about it in the following terms. Think about the "cross section" of the channel that the vessel is moving through (a channel which may be effectively infinitely wide). As the hull moves into that cross-section of water, water is forced "outwards" in order to accommodate the increasing cross section of the hull, i.e. it is accelerated to the left and right of the hull, as well as downwards towards the seabed (and also up into the air, but gravity is resisting net upwards movement of the sea surface so for the purposes of this we can think of it as fixed). As the water is accelerated "outwards" its static pressure reduces (as described by Bernoulli's principle). When it comes to the middle of the vessel where the cross sectional area of the hull is more consistent, the water does not need to "move outwards" as much so the effect is reduced. Towards the stern, the cross sectional area of the hull is reducing and so the water must rush "inwards" in order to "fill the space". Again, as it is accelerating, its static pressure will be decreasing. Therefore, as a vessel's speed increases there are areas of relatively lower pressure water near to the bow and the stern, and the ship naturally sinks lower into it. Thinking in the cross-sectional picture still: If the seabed is very close, then the fluid is not able to accommodate as much displacement in the "downwards" direction, so the water must be accelerated even faster to the left and to the right as the bow passes through. Similarly, as the stern passes through there is less water available to rise upwards and "fill the space" so water must be accelerated even faster from the left and from the right. Greater acceleration means greater decrease in static pressure, and so the ship sinks even further into the water.
I was fishing the south side of Sow and Pigs Reef off Cutty Hunk when that happened, didn't look like much from where I was, looked like she just slowed down. And then they radioed the USGC and said that they stuck "something"
Add the fact that my mum put a Welsh curse on QE2. My mum & dad were due on that trip on family rates- they didn't go as British deck & engine ratings were made redundant a short time before.
Fantastic video,I live with only water access,and at least 2 times each day , me to work..I need to get the kids to school,there is 200 m of mud at low tide between us and open sea,that’s the worst tides,( but you get those, and have to deal with them…) I have noticed ground effect heaps,and the suchion, when we pole over the mud and get to the water, we get this regular thing of the wake going in these big swirls,the boat is at constant speed but we get these suck swerls bigger than how wide the barge.a unconventional pattern after a lifetime at sea.we can rub the top of our pet flounders ,but they scoot well after we have pasted,which leaves me to think the pressure does something other than hold the boat down….. just a thought,,,,,,,regards from the far north of nz.
Bernoulli also affects ships maneuvering in parallel to each other - specifically Unrep, or replenishment at sea. Because of the suction between ships, one ship - usually the one being resupplied - wlll be canted slightly away from the other to maintain spacing against the suction of the low-pressure area (Bernoulli) between the ships. It’s not so apparent in photographs of modern ships at sea because the cant is small and the ships are farther apart, but if you look at photographs from the World War II era, especially when transferring personnel by high line, it’s noticeable.
So this is why it’s advised that you slow your speed down in shallow water, since the slower your going, the less squat you’d experience, and the higher in the water you’ll sit. But if they didn’t know about the boulder field, then they wouldn’t have been as cautious, and the unexpected shallowness of the water, combined with their speed, caused a greater amount of squat than they expected, resulting in them running aground.
I sailed on her as a baby, yet I recognised the profile on your thumbnail. My parents kept a brochure and it ended up on my childhood bookshelf and that was the one passenger ship I always looked at as a kid growing up.
Imagine having the balls to floor a newly built ship under a bridge that it doesn't fit under.
You missed the best part when you have to explain that in order for it to work the ship must be at full speed
It’s like those videos of people trying to get trucks under bridges they’re too tall for except because of hydrodynamics it actually works LOL
@@casey6556 wait how does this work. What's it called so I can have a look at this?
@@casey6556 It can work on those trucks too... technically... assuming you could generate enough downforce to fully compress the shock absorbers in the truck's suspension...
That's very similar to how Formula race cars have to drive fast enough to generate enough down-force to keep them stuck to the road around corners. If they don't drive fast enough, they'll skid off the road.
Holy crap, just built a 1 billion $ boat, put the last touch of paint on it then drive it at full speed toward a bridge with a physicist telling you not to worry, it will sink down in the water due to Bernoulli’s principle. Thats a butt clenching moment if ever I heard of one.
The magic of physics :D
I mean, if you're going to do anything with giant ships, you need a lot of trust in physicists already.
@BOB K In what scenario would the choice be between those?
@BOB K I'd trust a pharmaceutical scientist over a physicist if what we were talking about was pharmaceutical science and not physics.
@@NeatNit The difference is between Dr. Fauci's blue pill and Dr. Who's red pill 😂
Being a Captain and active in the Maritime Industry for more than 20 years, all I can say is that your videos should be teaching material. Congratulations!
I have used the effect to my advantage but did not know what it was called, I agree these are very educational because I only heard mention of, what we called, pressure effect once during my maritime studies. A captain, later harbour master and then lecturer talked of a US aircraft carrier approaching the east coast of Australia crossed the continental shelf into shallower water but still deep by any standard but she squatted and flooded through open portals aft and several sailors perished but the portals were 10m above waterline. So at speed , the depth changed from about 2000m to 250m, interesting story.
They are. You can buy the vids without ads on their page or order custom videos, for educational purposes.
He has mentioned it a while back that his videos were used as professional teaching materials. If I'm not mistaken, it was in multiple countries.
I actually took a course where they used some of the videos as material
I don’t know squat about ships.
"Captain, there is a bridge ahead and we are too tall! "
"Faster goddamnit! I said FASTER"
we missed you in the "Nord-Ostsee-Kanal" (North-Balticsea-Canal?).
Bridge to engineering "give me all you got, more speed !! "
I'm sorry captain! I'm giving you all she's got. I can give you no more! The engines are already at 120% capacity. I do not know how much longer she can take.
More passengers
Speedrunner strats: go fast enough and the game's physics engine bugs out and the ship sinks lower in the water.
I lived here during that event. I LOVED the anecdotal interviews following:
Nervous passenger to the Captain, "Captain, should we abandon the ship?"
Captain, "My dear, we are already on the bottom! Go back and have another glass of Champaign!"
*champagne
@@LetoDK who cares?
@@LeDerpLegend obviously he cares
Can you imagine the bullets being sweat in that bridge? And ON the bridge!?
@LeDerpLegend We're just sharing knowledge here. It's not "lol how stupid are you, it's spelled champagne", it's "thank you for sharing, by the way the correct spelling is champagne - common mistake, just thought I'd let you know"
As a seaman on a small ferry, I can see that every time we are about to land. As we slow down, the bow comes up from the water.
Ships have ground effect. Fascinating.ships and planes have so much in common
Air also acts as a fluid. Other than compressibility they're very similar
@@MisterLongShot_Official yeah its often said that air is a fluid. engineers i have met take that saying literally and would probably win in any argument
Isn't what he described more like the ground effect that refers to cars?
@@efthymis_mc34 both, the ground effect of a car, the ground effect of a low flying plane and the squat of a ship are all caused by Bernoulli's principle
@@boldCactuslad "its often said that air is a fluid"
FWIW, By definition, gases and liquids are fluids.
Fluids flow.
In everyday language we tend to use fluid to describe liquids more than we use it to describe gases. In scientific and industrial communications a fluid is just as likely to refer to a gas as refer to a liquid.
A tiny correction is that Oasis of the Seas didn't squat under a bridge over a river, but rather over the Great Belt strait in Denmark. She has telescoping funnels, and would have cleared the bridge by about a foot, but she barrelled at it at 23 knots, and thus gained another foot from squat. Still, 2 feet of clearance at 23 knots in a brand new ship, biggest in the world, under one of the most heavily trafficked car + train bridges in Europe, that must be a proper pucker event..
...thanks. I imagine such an undertaking required detail planning including such as wind and temperature limits, sea state and traffic control.
@@XPLAlN ..had a headwind, and burned a few thousand gallons more fuel than expected, oups, hit the bridge...
I don't care what anyone may say...these videos are some of the best on YT. I always learn interesting facts and the reasons behind them. Bravo!
you have no idea how happy your correct explanation of Bernoulli's principle at 2:49 made me :D
The fact that you said it occurs simultaneously and not one casues the other made me very happy indeed :D
There's so much important information in this one (again), i hope every skipper cruising through a canal knows this stuff... I can picture many situations where people overreact or simply react wrong due to not knowing the physics behind what's happening... oh boy. Thanks !
Yes, squat is taught!
As a pilot (air, not sea) these sorts of videos are incredibly interesting to see the similarities in air versus water behavior. Thank you for such great content.
Two things : The QE2 for me will always be one of the most beautiful ship designs ever created, and, this was a superb presentation.
Indeed
John Brown Clydebank turned out some beauties including the Queen Mary and the first Queen Elizabeth not to mention the 'mighty' Hood
I agree. I sailed on this ship from New York to Southampton. The departure was at full speed because she was outrunning a hurricane. We had a chart up showing where the Titanic sank. We got very close to the spot. It was quite emotional.
You can't always be too sure or careful.
It's amazing just how things can be explained.
A friend of mine was indeed too careful when abseiling, using an excess of safety equipment, and consequently got stuck half way down.
I once ripped my bottom on a rock...
You're also named Fanny
I actually felt the pain from reading your comment!
Same 😞
@@RNG-999 well, I'm glad I'm not British then, as a ripped fanny is much worse there than here...
I thought I had everybody on my side.
But I went and blew it all sky high.
And now she won’t even spare a passing glance.
All just because I ripped my pants.
As a sailor solo cruising on a sailboat, these videos help me navigate more intelligently and more safely. Thank you. I love your videos!
We experience exactly the same thing on our deep drafted narrowboat. Some of the UK canals are quite shallow in places you can be flat out and only be doing half the speed. also you can see the squat as the boat noticably sits lower in the water. we also experience bank effect and have also practiced the Texas chicken, works a treat if the other boater knows about it also, most don't though.
Great explanation. I'm surprised the captain chose to go over such a shallow area when deep water was closeby.
Same thing in the aviation industry. While planning a flight plan, we always used to plan the minimum flight level above the highest point the aircraft in question would fly over during the flight.
I was Mate this day on a nearby Sea-Land containership as we transited offshore from Boston to New York harbor and heard the VHF traffic on the air. Next day after we docked in Port Elizabeth NJ saw the story and interviews with passengers on TV.
Its so cool to see Bernoulli’s principle in use here sucking a ship downward, and also seeing it used in almost the same way to suck race cars closer to the ground to get more grip with ground effects. I love this stuff!
This is exactly how Venturi tunnels work in F1. Squats is pretty much the same thing as downforce.
Ah, man, finally a video i can REALLY relate to! I've been working as a 1st mate on the shallow seas north of The Netherlands and we really had to work with this phenomenon. Excellent video!
The more i watch these kinds of videos, the more i realize i do not know much about ships.. and i love it
Fascinating! I had no idea that squat existed. Thank you for teaching me.
I know Newton, Archimedes, and Bernoulli, but now I realize I didn't know squat.
Once again a video about something I never knew existed, around a subject I have minimal knowledge and information I doubt I will ever need to know but I am immensely happy that I now know it. Thank you, I love this channel.
Looks like those navigators didn't know squat! : 🥁
Take your thumbs up and show yourself out.
Spot on with that one. Apart from having been a Master.Mariner, before I retired, I had wa bespoke Narrow Boat built for cruising the inland waterways. This boat was 62ft long and weighed approximately 22 tons when fully fuelled up and with water tanks full. Passengers along for the ride, used to comment about the way the water level in the canal appeared to drop as we passed at 4 knots, near the bank. A narrowboat is a flat bottomed craft and the effect you mentioned was very much in evidence - I explained that if If I was travelling over. A patch of water which was c shallower than normal, I would slow right down. To many, this seemed n improbable solution - indeed, I came across, & passed boats which had become grounded, simply because they thought that their speed would carry them over. How wrong they were!.
I love these videos! I am a software engineer at a company that does under keel clearnace modelling and I did not know anything about how ships work before starting. Your videos give me a much better understanding of what it is that we are modelling.
I can't say I expected to hear the words 'chicken' and 'squat' in relation to ships' behaviour , but these are perfect explanations. Obviously things could've gone worse with the _QE2_ , if she'd been sailing somewhere where she could've sunk, considering the damage, but I bet that's a lesson her bridge crew never forgot.
So what happens if your mega millions ship that doesn’t fit under the bridge suffers an engine failure before it gets to the bridge…..or a loss of steering? Loved this video, I remember people lambasting a couple of captains who hit the bridge…..Why didn’t he slow down? Well now we know. 😮
Lloyds has a bad day.
A very large insurance claim.
@@AnthonyHandcock And the "names" get to pay! 😐 Stiff upper lips, gentlemen. 🧐
@@gus473 Bloated plutocrats! Capitalist running dogs etc etc etc.
@@danielkorladis7869 Not that large. The funnel would probably get damaged. And maybe the bridge.
*"Oasis of the Seas"* was build in Turku, Finland, in 2009, and she had to sail through danish waters to get from the shipyard in the Baltic Sea to the Atlantic Ocean.
She sailed via *Storebælt* - or The Great Belt, to Kattegat and onwards to the North Sea. Storebælt is not a river.
The bridge she had to pass under was *Storebæltsbroen* - The Great Belt Bridge.
Really interested video. I just have one catch, for all of us non American feet are a bit weird. Maybe for next videos you could also says how much is in metric, or at least in the video labels add also the distance in metric
(Don't say this loudly, but in the UK, it depends on your age as to whether you understand feet and inches or not.... I remember being at primary school and Miss Broad, our teacher, introduced a new sort of ruler. It wasn't flat as we were used to, and it had lots of smaller divisions on it... She was introducing us to centimeters! This was back in, oh, 1971 or 2, I think.
To this day I continue to be more comfortable using feet and inches when I'm measuring up for furniture, or sewing, for example, as it's what my Mum and Dad used at home...
Maybe now England's left the EU we'll go back to good old feet and inches, pounds, shillings and pence, and ounces, pounds and stones... 😅 😂😂 🤣🤣🤣!)
Hey, I get squat for Christmas every year!
That was a really cool reflection effect. Nicely done!
You must be on Santa's naughty list. Better straighten up and fly right.
Absolutely some of the best content on YT! I look forward to the next as I continue to review and learn from your previous videos. Bravo Zulu sir.
Catzoc, ukc calculations and squat explanation all in one video, well explained and tied together. Great job once again!
"sir we don't have the clearance to leave port, I recommend we deconstruct some of the antennae to make it under the bridge"
"Full steam ahead"
"What?"
I just love this channel so much. You have the ability to transfer knowledge in such a simple and understandable manner!
Thanks for telling me! I never really knew how this worked... at all...
"The Oasis of the seas was too tall. So by speeding up and using "squat" she made it" Now that is a ballsy move!!! Huge brass balls.
Watching your videos is always a pleasure. Im always looking forward to your next release. When i discovered your channel in the first place, i binged all your videos. Thank you so much for your excellent work!
I really enjoyed this video. Thank you for explaining all the various physics involved with speed and distance to the bottom of the sea floor. I had never thought the ship would squat like that in shallow water. Thank you for the content you have, it fills the hole that Modern Marvels left in my soul.
if this guy nonstop pumped out videos i would watch them until i died of dehydration and i’d be fine with it
Dying of dehydration while watching videos about ships is pure irony...
@@sysbofh i mean he does talk mostly abt salt water vessels
It would be interesting to see a video about the Herald of Free Enterprise disaster and how squat played a role in it.
we learned about using squat in the safety contour unit of ECDIS Lab this week. what a timely video
This video was very informative for me personally. I don’t get on boats often but I’m glad I know this 💯💯
I would prefer these videos without background music, I find it hard to concentrate when there's music playing at the same time. Other than that great video as usual, I love the animations and clear explanations, keep up the good work!
Seconded.
In this video I found it a tad distracting. I don't mind music generally, but I think this specific piece was too exciting.
I lived in Fairhaven Mass the day QE2 hit the rock. It was a big day for us! We went out and circled the ship in our bass boat to see what was up.
Excellent video again. Basically this is a same effect as the ground effect of an F1 car, resulting in downforce. I assume that this effect is stronger in water than in air due to the differences in density between water and air. Consequently, in water you need less speed to generate this effect. And, of course, ships don't have a suspension to prevent bottoming out 🙂
Even though it sounds a bit counter-intuitively (maybe), at slow speeds, trapping water can also work as cushion. If you berth a large vessel against a closed quay wall, with little under keel clearance and a small berthing angle, the water cannot "escape" quickly enough and will become trapped between the hull and the quay wall, consequently absorbing some of the berthing energy due to compression. This is actually taken into account when designing the fender systems. The reason this works, is because of the low speed and therefor the lack of a low pressure area along the vessels hull.
Imagine being the captain who has to drive a newly built, largest of its kind, billion dollar ship at high speeds at a bridge that it doesn’t fit under relying solely on the fact that it’ll sink a few feet because science. That must be a fun situation to be in.
This is more interesting than it should be. Keep it up
Well... Today I learned that there are actually vehicles that can generate more Downforce than a Formula 1 car!
Imagine a ship porpoising
@@efthymis_mc34 don't give the engineers any funny ideas! Someone gona hire Herman Tilke to come in and design a route into a harbour now with a constantly changing sea bed floor to make ships porpoise
Fascinating video. The ship passing manoeuvre was very interesting.
I LOVE this kind of physics!!
I only have a cabin cruiser but I never assume the charts are 100% accurate. The Great Lakes vary so much in depth You could be fine one year but in trouble the next year.
My Grandmas house was on the shore of Saginaw Bay. In the 60s you had to walk 1/4 mile to the waters edge. In the 80s it was right up to her door. Then a period of low water again. I'm out of state now but I hear the water is high again.
@terryboyer1342 I'm on south georgian bay (lake huron). Right now, the waters 2-3' lower than it was just 6 months ago. In 2021, it was around 5' higher than it should've been.
On top of that there’s been times where the change happens over a matter of days too, so one time you go up the water is high, you come back a few weeks later and it’s dropped substantially. Rarer but wild to see.
@@crinkly.love-stick Always wanted to visit your area and backpack in Bruce but it never worked out. My loss as it seems crazy beautiful from pictures.
@@satunnainenkatselija4478 That crossed my mind too.
Wow, I didn't know squat about how a ship works.
I was on the QE2 in 1982 and she ran aground in Puerto Rico 🇵🇷
I remember standing along the Columbia River when a Naval ship was running up river. I don’t know what the name of the vessel was but it was a destroyer, escort or a battle ship of some kind. Had large gun batteries forward and aft. Anyway since I don’t have the cool details I did notice as it was approaching the river level dropped a foot or two like the tide went out. This is a huge river that’s a mile wide where I was give or take. After it passed it was like the tide came in and the river level was 2 feet higher than it originally started. From my uneducated observation that in a river system the vessel had to be running in less water depth than any channel sounding since it was moving MASSIVE amounts of water just from its propeller wash. I’m sure other factors of displacement ect ect were part of the effect. I had never experienced that before. It was amazing to experience in person.
Absolute physics nerd, so this is one of my favourite videos to date! 😁
I use pressure effects ocean kayak fishing, there’s a spot right next to rocky walls/islands that more or less holds the boat in place near the rocks, it’s rare to actually hit the rocks at all even when the waves are leading right toward them. you can pretty much stay in the active fishing zone just off the rocks for hours with minimal corrections, you don’t have to worry about being constantly run aground, the pressure build up at the wall keeps you a few feet away. Common sense and conditions play a role of course, If they’re big waves actually breaking on the rocks, that’s a different story!
Easy and nice explanation!! Very good work!!
Hello from Clydebank, builders of the RMS Queen Elizabeth II!
These are my favorite videos you do. Love this. Thanks so much.
Surely then even if they didn't know about the boulders they would have known about the squat, and would have realised that they still wouldn't have managed to clear the area with 39' depth?
Once we had a similar issues with a hopper dredge that was damaged by a boulder in the channel while sailing over it during neap tide. After the hulk was repaired in dock we decided to check the squat of this vessel at 10Kts with an UKC of 3 meters . The squat at the stern turned out to be over a meter , the squat at the bow was less
Thank you thank you I love your videos. Please do one on the sinking of the HMS Birkenhead at Dangerpoint Western Cape. Pretty please!
Love your videos! Keep up the good work!
Great video! Thank you for making navigation fascinating!
I used to see those maps with sounding depths labeled as a kid and didn't know what they were. Thanks!
Thanks, so very much for great discussion of fluid dynamics: Bernoulli principal
One if my favorite days when casual navigation posts something
This video would have been very helpful when I was learning about squat in my general ship knowledge class.
Wow just 2 foot of water clearance for thousands of tones , Just to say that is about the height of a Bath you wash in.
Yes! Several years ago the thought "do ships experience ground effect?" popped into my head. I read into it and found the fascinating Oasis of the Seas example. Though my recollection was that she would have cleared the bridge anyway but the squat increased the safety factor. When this video started I shouted out to my monitor "It's ground effect?!", made me really happy to see I was right.
Air is just another fluid, it’s not uncommon for aerodynamic testing of components to be done in large water tanks
"Captain we are to high are going to hit that bridge!"
"FULL STEAM AHEAD!"
One correction: the bridge Oasis of the Sea had to fit under was not a river bridge but the Sorebaeltsbroen, which spans over the sea between Denmark and Sweden
Really interesting. I recall a news article about that ship being sped along it's way towards the bridge which was known to be too low. The reason was not communicated and this left interested parties unimpressed with the reckless path. Days passed without the vessel being seized , no captain arrested , and so on. Most of us think speed only raises a boat . A ship is not a boat however.
I have been saying this for you about the QE2 accident. As a thank you I will like and subscribe.
I now know the reasoning behind something that occurs on land. The 8'10 bridge has too many moving vans where the drivers are expecting squat and aren't traveling fast enough to get under the bridge ;)
This is the first time that I've ever heard about squat in a boat. As a captain of a large cruise ship they should have been well aware. 10% is nothing like the squat of up to 8ft that you mentioned.
Imagine getting the math wrong and crashing into a bridge at speed. Damn!
Thanks - not just for this video but for the many others I have seen - this is the least I can do!
Thank you so much! Its really appreciated!
US Nautical charts datum is “mean low water” which is less conservative than British or Canadian Hydrographic charts which are based on “lowest low water.”
This results in “negative tides” being more common in US tide tables than those just mentioned. It also makes it easier to over-estimate actual depths when navigating in shallow waters.
Actual clearance = chart datum + height of tide - vessel draft.
It is possible that the navigation officer saw the 39 foot datum but was sailing on a “negative tide” which made the actual depth less than chart datum, in addition to the reasons given in the video.
Excellent video! You explain the physics well...I actually understood!
I was there that day - she was going north in the Vineyard Sound, and I, south. I didn't know what the ship was, but I knew she absolutely didn't belong there. She was way out of the channel to the west, and far too close to the Elizabeth Islands. At least I wouldn't have been there with anything that big.
Anyway, she sure did stop suddenly.
You sure you've got your directions right? I wasn't there, but everything I read and saw indicated she was sailing basically West by Southwest at the time, with Cuttyhunk on her starboard side (to the North). She was not travelling East or Northeast (or North as you have it). Also, and I could be mistaken, but I understood that she had made this exact passage on previous occasions.
Since I’m a trainee sailor this video will help me emence so thank you verry much
Your videos are so interesting and so clearly explained, and it's very pleasing to learn about the physics involved in ships and boats and seas and canals etc. I'm all for life long learning, and you're a good teacher 😊 so thanks!
Very interesting, as always. Thanks for sharing this with us.
I watched that video of the cruise ship speeding up to clear the bridge. It was awesome!
The description of the squat effect involving Bernoulli's principle in the video is very good, however taken together with the 2-D animation on screen at the time, people may arrive at a slightly inaccurate idea about why the water under the hull must speed up in the first place. I completely understand that this style of animation is usual for the channel, but for anyone who wants to have a fuller picture it may help to think about it in the following terms.
Think about the "cross section" of the channel that the vessel is moving through (a channel which may be effectively infinitely wide). As the hull moves into that cross-section of water, water is forced "outwards" in order to accommodate the increasing cross section of the hull, i.e. it is accelerated to the left and right of the hull, as well as downwards towards the seabed (and also up into the air, but gravity is resisting net upwards movement of the sea surface so for the purposes of this we can think of it as fixed). As the water is accelerated "outwards" its static pressure reduces (as described by Bernoulli's principle). When it comes to the middle of the vessel where the cross sectional area of the hull is more consistent, the water does not need to "move outwards" as much so the effect is reduced. Towards the stern, the cross sectional area of the hull is reducing and so the water must rush "inwards" in order to "fill the space". Again, as it is accelerating, its static pressure will be decreasing.
Therefore, as a vessel's speed increases there are areas of relatively lower pressure water near to the bow and the stern, and the ship naturally sinks lower into it. Thinking in the cross-sectional picture still: If the seabed is very close, then the fluid is not able to accommodate as much displacement in the "downwards" direction, so the water must be accelerated even faster to the left and to the right as the bow passes through. Similarly, as the stern passes through there is less water available to rise upwards and "fill the space" so water must be accelerated even faster from the left and from the right. Greater acceleration means greater decrease in static pressure, and so the ship sinks even further into the water.
Awesome explanation! I didn't know about that. Thanks!
I was fishing the south side of Sow and Pigs Reef off Cutty Hunk when that happened, didn't look like much from where I was, looked like she just slowed down. And then they radioed the USGC and said that they stuck "something"
great explanation sir!
Just noticed this works on basically the same principle as F1's new ground effect cars. At least ships don't have to deal with porpoising hahaha.
It's amazing that the squat adds a full quarter of her draft.
Add the fact that my mum put a Welsh curse on QE2. My mum & dad were due on that trip on family rates- they didn't go as British deck & engine ratings were made redundant a short time before.
Fantastic video,I live with only water access,and at least 2 times each day , me to work..I need to get the kids to school,there is 200 m of mud at low tide between us and open sea,that’s the worst tides,( but you get those, and have to deal with them…) I have noticed ground effect heaps,and the suchion, when we pole over the mud and get to the water, we get this regular thing of the wake going in these big swirls,the boat is at constant speed but we get these suck swerls bigger than how wide the barge.a unconventional pattern after a lifetime at sea.we can rub the top of our pet flounders ,but they scoot well after we have pasted,which leaves me to think the pressure does something other than hold the boat down….. just a thought,,,,,,,regards from the far north of nz.
"How did she rip her bottom on this rock?"
Our sex life is none of your business doctor.
this sounds like really quite a beautiful use of the principles of math's & physics... but also, like it's an insanely dangerous thing to do... wow!
Bernoulli also affects ships maneuvering in parallel to each other - specifically Unrep, or replenishment at sea. Because of the suction between ships, one ship - usually the one being resupplied - wlll be canted slightly away from the other to maintain spacing against the suction of the low-pressure area (Bernoulli) between the ships. It’s not so apparent in photographs of modern ships at sea because the cant is small and the ships are farther apart, but if you look at photographs from the World War II era, especially when transferring personnel by high line, it’s noticeable.
So this is why it’s advised that you slow your speed down in shallow water, since the slower your going, the less squat you’d experience, and the higher in the water you’ll sit. But if they didn’t know about the boulder field, then they wouldn’t have been as cautious, and the unexpected shallowness of the water, combined with their speed, caused a greater amount of squat than they expected, resulting in them running aground.
Over 765,000 views disproves your parting comment. Thanks for the video. Subscribed. 🙂👍
I sailed on her as a baby, yet I recognised the profile on your thumbnail. My parents kept a brochure and it ended up on my childhood bookshelf and that was the one passenger ship I always looked at as a kid growing up.