JALhazmat
Super Anarchist
Just as well the boats don’t sail in diagrams then
INEOS Team GB
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robingimblett
Member
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With windward heel the yacht's righting lever increases and the sail overturning lever decreases so in theory they could hold more power in the sails for more speed. The leeward foil is also angle more to windward = greater windward lateral force. But the hull and windward foil is closer to the waves.
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With windward heel the foil is providing more lift to windward and allowing the boat to sail higher. If it was a drag race and all about speed then you would want the rig upright. Windward heel is also helps you get up on the foil quickly. Nice drawings Robingimblett much appreciated.
enigmatically2
Super Anarchist
I disagree with that diagram. The force on the sail is at right angles to the sail, not horizontal. Thus the sail force will provide an upward component which increases heeling moment 8or decreases RM)
robingimblett
Member
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It's assumption the wind force is horizontal parallel to the water. If in the windward heel diagram sail force were kept perpendicular to the mast and then sail lever length was unchanged, the righting moment lever still increases so it's still more power efficient.
enigmatically2
Super Anarchist
I don't think that is necessarily true. Because the sail lever actually increases, it doesn't stay the same. It will increase by 5780sin(A) where A is the angle of windward heel
The_Alchemist
Super Anarchist
This is a great discussion. It is easy to just say or observe that it works with a Moth, but it is different to understand how it works. And obviously AM thinks it helps in the AC40/75, which is a different animal.
robingimblett
Member
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This discussion is turning to more general boat heel / foil concept etc. Do we think we should take it over to the 'Boats and foils comparison' thread that has all the AC36 physics discussion?
JALhazmat
Super Anarchist
@The_Alchemist, downvoting it doesn’t make it any less true. 🙄
johnstarks
Member
Could windward heel slightly lower the CE of the sail? This would reduce sail roll moment which would be beneficial in breeze
enigmatically2
Super Anarchist
Clearly in high mode on the w at times, pointing pi/8 radians higher than anyone else has achieved in any conditions
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The_Alchemist
Super Anarchist
It was in response to your tendency to be a jackass instead of just participating in discussions.
JALhazmat
Super Anarchist
I spend far too much time listening to people talking about theories that they have developed while dismissing the actual experience of people doing the sport or activity that they’ve developed their theory on, so if that means I am less tolerant of some of the Flights of fancy that you and others partake in then please forgive me.
there are reasons we don’t have super cavitating foils in the Americas cup. There are reasons we don’t have morphing foils in the Americas cup. There are reasons that Windward heel is a desirable mode for an AC yacht. sorry but that’s the truth
there are reasons we don’t have super cavitating foils in the Americas cup. There are reasons we don’t have morphing foils in the Americas cup. There are reasons that Windward heel is a desirable mode for an AC yacht. sorry but that’s the truth
enigmatically2
Super Anarchist
That's all true Jal, but I think windward heel in an AC boat has quite different effects and benefits from a kite foiler or moth.
In the kite foiler or moth it promotes Lyft which is of benefit. But that same lift on an AC boat reduces RM so is of mixed benefit.
On the other hand on an AC boat it increases end-plating which is not really a factor in moths and especially kite-foilers
Also, the greater control that an AC boat has through flap positioning means that they can control lift in more complex ways, including at least in theory to windward, without changing heel angle.
And in the discussions about the merits of W, T and Y foils there is some learning from other boats (and I know you know a lot more about foils than me and I always listen to you for that reason), but there are some factors unique to these boats because of the rules and consequent flap designs
In the kite foiler or moth it promotes Lyft which is of benefit. But that same lift on an AC boat reduces RM so is of mixed benefit.
On the other hand on an AC boat it increases end-plating which is not really a factor in moths and especially kite-foilers
Also, the greater control that an AC boat has through flap positioning means that they can control lift in more complex ways, including at least in theory to windward, without changing heel angle.
And in the discussions about the merits of W, T and Y foils there is some learning from other boats (and I know you know a lot more about foils than me and I always listen to you for that reason), but there are some factors unique to these boats because of the rules and consequent flap designs
terrafirma
Super Anarchist
Clearly there is more to it than that otherwise why would they have done it.? For example could a boat with more control and maneuverability win more of the starts and then hold off a slightly faster boat? Luna Rossa achieved this vs ETNZ in the final.
enigmatically2
Super Anarchist
You mean that is part of the aim of the w because it is inherently more stable?
Ok obviously you are using the flaps to get up on the foil and maneuvering but you want to use them as little as possible. I think Rob, Mozzy's mate suggested no flaps and use the rudder rake to get up on the foils which I still think is a good idea. There are quite a lot of variables so one can only really comment about the general design concepts rather than specific details.
