A catamaran sail is not an aircraft wing and aspect ratio / Reynolds numbers are only part of the story.
Yes, but both move through the same medium, the air, which belongs to the same law of physics.
The wider iCat sail will require the airflow flowing over it to contain more energy to overcome the (longer stretch of) negative pressure gradient towards the leech.
Actually, assuming the Icat sail has the same cp-peak and the same pressure recovery over its longer chord, it will take out more energy of the flow, hence more lift. That's the area effect, bigger sail, more lift. Both sails could start from the same cp-peak, since this is the real physical limit. Both sails will recover the cp to about zero at the trailing edge. However the sail with the longer chord has this pressure gradient over a longer distance, hence less steep, hence more stable, less prone to stalling.
Ahh, but have you factored in the energy balance ? Or would you claim that a 150 sq. mtr. sail behind the same 8.1 luff will have 10 times additional lift ? Note that I was talking about light winds right !
Of course, you cannot take out more energy from the wind as there is in it. However there is plenty of energy, if the wind is blowing constantly in a large area. That's what most people would call favorite sailing conditions. Having just small patches of wind whispering here and there (what you call light wind?) might such a case of limited energy.
When the craft moves at 2.5 m/s then a total area of 5*8.1 = 22.5 sq. mtr is swept for energy
There is never a finite volume which is affected, since both the up- and downstream air is affected (even the air above the sail). That follows directly from the principle of conservation of momentum and mass.
Assuming same mast height and luff length, a 16sqm sail will be favored above a 15.5sqm sail on a run or downwind leg.
Cheers,
Klaus
