baxterbradford wrote: ↑
Sat Dec 02, 2017 9:30 pm
Isn't the sinker issue the difference between static and dynamic buoyancy Peter which is more affected by relative density of saline vs fresh water? Hydrofoil having virtually no buoyancy and producing almost all dynamic lift.
The sinker issue when uphauling, or at least when no speed, is the static buoyancy difference indeed so the relative density is the very difference, correct.
And a hydrofoil wing will lift proportional to the water density (given the same speed), meaning you have a tad more lift with the same size wing in salty water.
I have left out the hydrofoil buoyancy, it is neglectable.
So you are right, it is two different physical things, but they are affected with the same amount
And plummet is spot on, the air temperature difference means somewhat more, as air can be compressed a lot more than water, so from 26 to 4 degree air temp you get 8 % more lift from the kite.
And in reality, in the given conditions from winter 4 degree water to somewhere with 26 c water, the air difference could easily be 30 degree, which means 11 % more pull from the kite, when cold.