Thank you for watching. Quick Question: Did you enjoy the 3d animations in this video? I am still a beginner at them, but if they are successful, I will definitely be working more into future videos.
But I still want to know *how it works* . That is, how can the pitch be changed on a rotating part like that? What is the mechanical arrangement that accomplishes this?
@@SukacitaYeremia merchant marines are the ones on the ship. We need it for any sort of Maneuvering. Also, as an engineering, cause I'm gonna be the one to fix that shit
Thank you for this video. I eally love your videos, even though I am not a sailor but rather an aviator :): We have so many things in common, like e.g. the Controllable Pitch Propellers, you also have them on some planes :).
Aviation was inspired so much by sea navigation, they took all the classy parts! That's why I don't like when airline pilots uniforms don't include the cap, because even if it is useless to a pilot, it's just pure naval tradition.
The same technique is used to control lift in helicopters with collective pitch the rotor blades rotate to alter the angle of attack, not sure if it's really a thing in propeller driven fixed wing aircraft though they do usually have a setting for 0 degree pitch but this is of course intended for use in the event of engine failure in order to reduce drag from the windmilling prop.
on heavier then air fixed wing aircraft unless specifically designed they will not change. on lighter that aircraft's (airships/blimps) it does work very similar to that of a naval ship. but then the entire airship just behaves more like a boot then anything else.
In fixed wing aircraft you can have both. Typically, the lighter the aircraft, the more likely to have a fixed prop (not even a "feathered", i.e. low drag, position). The other type is a "constant speed" prop, which is set to a set RPM and keeps it by varying pitch. The engine power then determines how coarse / fine a pitch you'll get. (Or at least thats a glider pilots understanding of propellers ;) )
A control pitch propeller is not the same as a variable pitch propeller, a variable pitch propeller is normally a fixed pitch propeller where the pitch varies along the length of the blades. It's also wrong to state that a control pitch propeller runs at a constant speed, a lot are controlled by a combinator which changes both the pitch and speed simultaneously to stop excessive cavitation on the blades.
"a variable pitch propellor is normally a fixed pitch propellor". You are referring to blade twist which is necessary for all props and is the fixed reduction of blade angle from root to tip. That is not variable pitch. Pitch refers to the nominal distance the screw will advance in one revolution. Any time you can alter the angle of the blade in service you have a variable pitch prop. It could be a couple of settings, or it could be controllable within a range, or it could be 'constant speed' whereby the pitch control itself acts as the engine governor.
Airplanes have these two. On an airplane, it is called a constant speed propeller because it causes the engine to run at a constant speed. Usually on an airplane with a constant speed prop, the propeller control determines the engine speed, and the throttle determines the propellers pitch. It sounds strange, but there is an oil pressure modulator operating the propeller to make that happen.
Here's a fun anecdote: I worked on one ship with an engine that couldn't reliably start because of a fault in the start air system. Every time we had to start the engine, it took multiple attempts, and we had to reposition it with the turning gear between each attempt. Needless to say, it was a pain in the ass and we were eager to get it resolved. Before that happened, we had to transit the Panama Canal. Fortunately for us, we were able to keep the engine idling for the entire transit so that we never had to reveal our engine fault. I doubt the PCA would have allowed us to start the transit if they knew our engine wasn't working properly
Sir i love your videos , very helpful. please make a video on Difference between Speed over ground And Speed over water. Plz You are helping a lot of mariners. Keep it up. Love from india
The advantage of fixed pitch prop (FPP) is that you can still have steering when the prop is stopped as long as the vessel is still moving ahead or you still have water flowing over the rudder, such as if the tide is acting against you from ahead. This makes slowing a ship down a lot quicker and more controllable. By contrast a Controllable pitch propeller (CPP) is more difficult to slow down as you have to gradually reduce the pitch to maintain steering. When a CPP is at zero pitch the blades generally don’t let sufficient water through to have an effect on the rudder, thus losing your ability to steer. Pitching ahead slightly opens the blades up to allow water flow through to the rudder to enable steering, but the disadvantage is that the speed may increase ahead. The advantage of CPP is that the prop always turns the same direction. You can get astern propulsion very quickly by pitching astern and let the blades pitch the other way without having to stop the prop and start it turning the other direction, whereas the FPP will need to be slowed down to a complete stop before rotating the other way. The time it takes to go from full ahead to full astern with a CPP is very quick (providing you don’t overload your engines) and very slow with a FPP. Knowledge of the advantages and disadvantages of each are important, so you can use each to your advantage and mitigate the risk of their disadvantages. Chris - Marine Pilot
Hi, I don't know much about ship's engineering but I do recall watching a video about how a propeller's geometry has to take into account many factors, including formation of cavities on the propellers, during the design process. How can one optimize the design of a propeller when the propeller's pitch can change?
Yes, when two propellers are used they will turn in opposite directions. In Controllable Pitch Propellers ships (CPP), they will generally turn inwards to maximise thrust over the rudders. In Fixed Pitch Propellers ships (FPP), they will turn outwards in order to maximise the "Paddlewheel Effect" when one engine is ahead and the other astern. Since both propellers will turn in the same direction, at low speed the stern will have maximum movement, desirable when berthing/slipping from a wharf. No twin propeller ship will have both propellers going the same direction when going ahead/astern.
Well I'm sure it's possible to put 1000 tiny propellers onto a large ship instead of one or two gargantuan ones. But that would mean 1000 drive shafts and so forth. And a hell of a transmission!
With a twin screw CCP one assumes they spin in opposite directions, so surely this counters any prop walk even at zero speed? I've tied many ships up from a small launch and the ones with CCP still disturb the water at zero speed but not in a forward moving way.
I had an idea for small outboard motors and propellers. If you can create a small enough variable pitch propeller, you can increase efficiency, speed, and acceleration of the boat. I have a 16ft mirrocraft with a 25hp engine (the limit at the lake). I enjoy water skiing, but it is difficult to get up if there are 3 or more adults on board. The only way to do so is to put a shallower pitched prop on to generate more thrust, but then the top speed is greatly reduced diminishing the fun. I have not done the math or even given this idea any serious practical thought if it would work. My thinking is, in the skiing example, to start off with a shallow pitch to create the thrust to overcome the immense drag of a person sitting in the water, then to gradually increase the pitch to increase the speed once the skier is upright and only has the drag of the skis themselves to worry about
This is precisely the origin of variable pitch in aircraft propellers and the reason why a lot of early speed record planes were floatplanes. As they didn't have variable pitch props and were designed for high speed, obviously, they needed longer runways to get up to flying speed than could reasoanbly be built on land.
You can make a small variable pitched propeller, but it would be an expensive retrofit to existing outboard engines. You would need a new lower unit at least. Variable pitch uses hydraulics to control the pitch so you would need some way of delivering the pressure to your outboard. They do exist in small sizes though, I've seen them installed on sailboats.
Of we change the way we assemble the propeller also important because with vortex technology could turn propeller lose and so we could attact propeller by the clamps and pin lock instead of taped toothed turn also variable pitch can utilize the inertia conservation to travel against current and goes fuel less
Not instantly, they are not bicycles and they don't move on solid surfaces. The difference is that FPP ships need time to slow down, reverse and then increase speed at the opposite direction. CPP ships maintain the shaft speed and they just change the pitch. The pros have been posted by a user in another comment above.
Fin fact, the internal design on KaMeWa and Rolls-Royce propellers are the same as in Kaplan hydro power turbines from KMW. The main difference are the blades. Great Swedish design, reliable and relatively cheap to manufacture
The very large diesel engines used in ships fitted with variable pitch propellers are designed to run at a very specific rpm that maximizes the efficiency of the engine. These engines also don't really tolerate variations in their operating speed very well. Reducing the pitch does make the engine less efficient, however, slowing the engine down also makes it less efficient. The portion of the power generated used to simply overcome the friction inherent in the engine increases as you decrease engine speed. Realize that the vessel, while underway, will be at it's designed speed as much as possible during the crossing. Reducing the speed is only done if the vessel encounters bad weather, has an issue that requires it to reduce speed, or while approaching a port. Many large cargo vessels these days don't even have a transmission installed - the engine is directly coupled to the shaft. The variable pitch propeller is controlled using hydraulic power, eliminating the need for a costly and heavy gearbox that requires expensive maintenance.
I don’t know why you would have one variable pitch propeller and a fixed pitch propeller it makes a lot more sense to me to have two fixed or two variable
As I was watching the beginning of the animation, I couldn’t help but notice that the duel propellers were NOT contra-rotating, like twin engine aircraft to cancel torque. Why was that?
@@cr4zyj4ck Huh? What? Yeah sure you'll still need a propeller, did i ever say you dont have to? You dont have to have all the tech and engineering to change the aoa because you can easily adjust the rpm of an electric motor.
Thank you for watching.
Quick Question: Did you enjoy the 3d animations in this video?
I am still a beginner at them, but if they are successful, I will definitely be working more into future videos.
Very nice dude.Include it next time.(what kind of program u are using?)
Thanks. The 3d is made using Blender.
Impressed by the effort-and the pro looking result
We loved it!
It is perfect!!! I am a commercial diver, and I’m learning so much with you!!! It is so usefull for me
Educational videos with great animation is better than going to school for 4 years.
It’s almost like controllable speed propellers (more often known as the constant speed propeller) on aircraft. Very informative and thank you!
But I still want to know *how it works* . That is, how can the pitch be changed on a rotating part like that? What is the mechanical arrangement that accomplishes this?
Check this video and you will understand. ruclips.net/video/-hu7LuT3q58/видео.html
They use a governor, it's the same setup used in aviation. Constant speed prop. The governor diverts engine oil to or from the prop hub.
In my project, there is a HPU to controll the pitch.
it used hydraulic pump tp control the pitch
hong3ever Hydrodynamic Propeller Universe???
Very informative thank you. Yes animation very good as well.
Thanks for feeding back Ali. Glad you enjoyed it!
This was actually very good to help visualize variable pitch airplane props as well!
As a merchant marine student this stuff is super interesting to me
I thought marine merchants won't need stuff like this... Is it for docking purposes?
@@SukacitaYeremia merchant marines are the ones on the ship. We need it for any sort of Maneuvering. Also, as an engineering, cause I'm gonna be the one to fix that shit
Thank you for this video. I eally love your videos, even though I am not a sailor but rather an aviator :): We have so many things in common, like e.g. the Controllable Pitch Propellers, you also have them on some planes :).
Aviation was inspired so much by sea navigation, they took all the classy parts!
That's why I don't like when airline pilots uniforms don't include the cap, because even if it is useless to a pilot, it's just pure naval tradition.
The same technique is used to control lift in helicopters with collective pitch the rotor blades rotate to alter the angle of attack, not sure if it's really a thing in propeller driven fixed wing aircraft though they do usually have a setting for 0 degree pitch but this is of course intended for use in the event of engine failure in order to reduce drag from the windmilling prop.
on heavier then air fixed wing aircraft unless specifically designed they will not change. on lighter that aircraft's (airships/blimps) it does work very similar to that of a naval ship. but then the entire airship just behaves more like a boot then anything else.
In fixed wing aircraft you can have both. Typically, the lighter the aircraft, the more likely to have a fixed prop (not even a "feathered", i.e. low drag, position). The other type is a "constant speed" prop, which is set to a set RPM and keeps it by varying pitch. The engine power then determines how coarse / fine a pitch you'll get. (Or at least thats a glider pilots understanding of propellers ;) )
as always, nicely illustrated, brilliant
A control pitch propeller is not the same as a variable pitch propeller, a variable pitch propeller is normally a fixed pitch propeller where the pitch varies along the length of the blades. It's also wrong to state that a control pitch propeller runs at a constant speed, a lot are controlled by a combinator which changes both the pitch and speed simultaneously to stop excessive cavitation on the blades.
"a variable pitch propellor is normally a fixed pitch propellor". You are referring to blade twist which is necessary for all props and is the fixed reduction of blade angle from root to tip. That is not variable pitch. Pitch refers to the nominal distance the screw will advance in one revolution. Any time you can alter the angle of the blade in service you have a variable pitch prop. It could be a couple of settings, or it could be controllable within a range, or it could be 'constant speed' whereby the pitch control itself acts as the engine governor.
@@XPLAlN NERD
And with this last video I've seen every video you've posted! Fantastic work, can't wait for more stuff!
You are very good at everything boat . I've learned a lot . Thank you .
Very good geekyness here. Please do more on these topics.
Airplanes have these two. On an airplane, it is called a constant speed propeller because it causes the engine to run at a constant speed. Usually on an airplane with a constant speed prop, the propeller control determines the engine speed, and the throttle determines the propellers pitch. It sounds strange, but there is an oil pressure modulator operating the propeller to make that happen.
Here's a fun anecdote: I worked on one ship with an engine that couldn't reliably start because of a fault in the start air system. Every time we had to start the engine, it took multiple attempts, and we had to reposition it with the turning gear between each attempt. Needless to say, it was a pain in the ass and we were eager to get it resolved. Before that happened, we had to transit the Panama Canal. Fortunately for us, we were able to keep the engine idling for the entire transit so that we never had to reveal our engine fault. I doubt the PCA would have allowed us to start the transit if they knew our engine wasn't working properly
Thanks for sharing, excellent video!
Great as always
Công Chánh is here 💪💪
Sir i love your videos , very helpful.
please make a video on
Difference between
Speed over ground
And
Speed over water.
Plz
You are helping a lot of mariners.
Keep it up.
Love from india
They are on airplanes too . for speed and power ones with a prop
It's only for propellers and not turbo fan or turbo jet engines, they also have this on helicopters but more controls rather than forward and backward
I would really like to know more about the advantages and disadvantages of each.
The advantage of fixed pitch prop (FPP) is that you can still have steering when the prop is stopped as long as the vessel is still moving ahead or you still have water flowing over the rudder, such as if the tide is acting against you from ahead. This makes slowing a ship down a lot quicker and more controllable. By contrast a Controllable pitch propeller (CPP) is more difficult to slow down as you have to gradually reduce the pitch to maintain steering. When a CPP is at zero pitch the blades generally don’t let sufficient water through to have an effect on the rudder, thus losing your ability to steer. Pitching ahead slightly opens the blades up to allow water flow through to the rudder to enable steering, but the disadvantage is that the speed may increase ahead.
The advantage of CPP is that the prop always turns the same direction. You can get astern propulsion very quickly by pitching astern and let the blades pitch the other way without having to stop the prop and start it turning the other direction, whereas the FPP will need to be slowed down to a complete stop before rotating the other way. The time it takes to go from full ahead to full astern with a CPP is very quick (providing you don’t overload your engines) and very slow with a FPP.
Knowledge of the advantages and disadvantages of each are important, so you can use each to your advantage and mitigate the risk of their disadvantages.
Chris - Marine Pilot
@@marinepilotchris3048 FPPs are more durable.
MihalisNavara Absolutely 👍
Reduced chance of failure with less moving parts.
I had run this CPP arrangement on Navy ships.
Hi,
I don't know much about ship's engineering but I do recall watching a video about how a propeller's geometry has to take into account many factors, including formation of cavities on the propellers, during the design process. How can one optimize the design of a propeller when the propeller's pitch can change?
Both propellers are turning the same way? Is that right? I’ve learn that when to propellers, one is clockwise and the other is counterclockwise.
Yes, when two propellers are used they will turn in opposite directions. In Controllable Pitch Propellers ships (CPP), they will generally turn inwards to maximise thrust over the rudders. In Fixed Pitch Propellers ships (FPP), they will turn outwards in order to maximise the "Paddlewheel Effect" when one engine is ahead and the other astern. Since both propellers will turn in the same direction, at low speed the stern will have maximum movement, desirable when berthing/slipping from a wharf. No twin propeller ship will have both propellers going the same direction when going ahead/astern.
A big propeller is for big boats
And small propellers are for small boats. God damn I didnt know that 0:10
Well I'm sure it's possible to put 1000 tiny propellers onto a large ship instead of one or two gargantuan ones. But that would mean 1000 drive shafts and so forth. And a hell of a transmission!
SARCASM 100
Wonderful video, even the 3d is great. Too bad the pitch on my tanker prop is stuck in the reverse position.
Thanks Shem. Hope it gets fixed soon
Good information
I wish I could reduce the pitch of my wife's voice when she is yelling at me to slow my boat down all the time.
@Vladimir Vcelar hahahaaaa
If you play The Make Believes - Dead of Winter loud enough you’ll mute her.
Wow!! I didn’t know constant speed propeller was from ship principle. I thought it started from aviation
Can you make a video on how propellers takes the ship forward
Thanks Ashrit. It sounds like an interesting topic. I will add it to my list of video to make.
is the cpp always clockwise, or anticlockwise ? while going astern.
Amazing .good job👌
With a twin screw CCP one assumes they spin in opposite directions, so surely this counters any prop walk even at zero speed? I've tied many ships up from a small launch and the ones with CCP still disturb the water at zero speed but not in a forward moving way.
Very interesting... thanks!
a video on voith-schneider propellers would be cool, and/or one on tugs :-)
Please I want to know how much is cost FPP and CPP?
I had an idea for small outboard motors and propellers. If you can create a small enough variable pitch propeller, you can increase efficiency, speed, and acceleration of the boat. I have a 16ft mirrocraft with a 25hp engine (the limit at the lake). I enjoy water skiing, but it is difficult to get up if there are 3 or more adults on board. The only way to do so is to put a shallower pitched prop on to generate more thrust, but then the top speed is greatly reduced diminishing the fun.
I have not done the math or even given this idea any serious practical thought if it would work. My thinking is, in the skiing example, to start off with a shallow pitch to create the thrust to overcome the immense drag of a person sitting in the water, then to gradually increase the pitch to increase the speed once the skier is upright and only has the drag of the skis themselves to worry about
This is precisely the origin of variable pitch in aircraft propellers and the reason why a lot of early speed record planes were floatplanes. As they didn't have variable pitch props and were designed for high speed, obviously, they needed longer runways to get up to flying speed than could reasoanbly be built on land.
You can make a small variable pitched propeller, but it would be an expensive retrofit to existing outboard engines. You would need a new lower unit at least. Variable pitch uses hydraulics to control the pitch so you would need some way of delivering the pressure to your outboard.
They do exist in small sizes though, I've seen them installed on sailboats.
Of we change the way we assemble the propeller also important because with vortex technology could turn propeller lose and so we could attact propeller by the clamps and pin lock instead of taped toothed turn also variable pitch can utilize the inertia conservation to travel against current and goes fuel less
So by conservation of angular momentum by reverse angle of attack of the propeller we could propel the ship against water current
very nice..thanks
Thanks Darrel
Thank you.
Question does the vessel with CPP stop instantly? Please share advantages of each side
Not instantly, they are not bicycles and they don't move on solid surfaces. The difference is that FPP ships need time to slow down, reverse and then increase speed at the opposite direction. CPP ships maintain the shaft speed and they just change the pitch. The pros have been posted by a user in another comment above.
The only way to stop a ship instantly is to run her aground. But that's not something you want to do lol.
Is that possible if reversing tbe ship with fixed pitch propeller using the engine? (By inversing firing order
Thanks👍
excellent
Fin fact, the internal design on KaMeWa and Rolls-Royce propellers are the same as in Kaplan hydro power turbines from KMW. The main difference are the blades.
Great Swedish design, reliable and relatively cheap to manufacture
Thank you. This is what I really wanted to know. just so informative.
So it's like the collective on a helicopter, RPM is the same but pitch determines whether you ascend or descend.
So which 'setting' if more fuel economical for long trips while holding the same speed?
It all depends on the engine and shape of the hull and propeller.
Thanks vry much sir
It so good
Uuummm twin props must counter rotate to negate prop torque
does a salvage tug boat or ship
But isn't it way more fuel inefficient when the prop spinns at fast or slow (rotation) speeds in relation to the movement speed
The very large diesel engines used in ships fitted with variable pitch propellers are designed to run at a very specific rpm that maximizes the efficiency of the engine. These engines also don't really tolerate variations in their operating speed very well.
Reducing the pitch does make the engine less efficient, however, slowing the engine down also makes it less efficient. The portion of the power generated used to simply overcome the friction inherent in the engine increases as you decrease engine speed.
Realize that the vessel, while underway, will be at it's designed speed as much as possible during the crossing. Reducing the speed is only done if the vessel encounters bad weather, has an issue that requires it to reduce speed, or while approaching a port.
Many large cargo vessels these days don't even have a transmission installed - the engine is directly coupled to the shaft. The variable pitch propeller is controlled using hydraulic power, eliminating the need for a costly and heavy gearbox that requires expensive maintenance.
Yeah I was thinking about how at the mechanical it works.
Check this video and you will understand. ruclips.net/video/-hu7LuT3q58/видео.html
Is this same for the Titanic
Titanic had fix pitched propellers.
If only hahah
I don’t know why you would have one variable pitch propeller and a fixed pitch propeller it makes a lot more sense to me to have two fixed or two variable
I don't think anyone actually does that, it was for illustration purposes only.
Many airplanes use a similar CV system.
Thanks a lot, you have cleared my doubts.
Cheers Meraj!
So it's a CVT for boats
Ho Ngoc Thien came here.
Only if the bismarck had these
While this was a good explanation regarding low-to-cruise speed, you seem to have totally forgotten cruise-to-max speed.
😲😲😀😀👍
As I was watching the beginning of the animation, I couldn’t help but notice that the duel propellers were NOT contra-rotating, like twin engine aircraft to cancel torque. Why was that?
Why is this a German vessel?
Why are the propellers bloody
They reflect the color of the hull.
MihalisNavara no they’re bloody why are they bloody
Tolong diartikan dong ke bahasa indonesia plisz
👌🏼🤚🏼🍺🍺
or you just use an electric engine and bypass all that expensive engineering....
The electric motor still needs a propeller otherwise how else are you going to push the ship through the water.
@@cr4zyj4ck Huh? What? Yeah sure you'll still need a propeller, did i ever say you dont have to? You dont have to have all the tech and engineering to change the aoa because you can easily adjust the rpm of an electric motor.
Like
.
Swashplate propeller 😂😂😂
I don’t care
Then don't watch the video.