BEACHSTART said..
Foil has less drag then normal wsurf(at lower speed range) ,this allow you to use higher COP in high aspect ratio sail,which has better L/D ratio.
In theory,if drag is zero you can hold infinity power of sail,becuse there is nothing to resist to this huge sail power.
example
car pull you with rope when you are on skateboard :
a)if you are on ice,then drag is low and tension in rope (your thrust)will be very low too,you can move above 100km/h easy..
b)if you are on sand,drag is huge,tension in rope will be huge too,maybe you can hold up to 20km/h because you can not hold so much power with your weight which resist to tension in rope...
(in both situation max power/tension in rope which you can hold is the same,it depends only on your weight but when you reach this max rope tension(your thrust) on ice you go very fast and on sand maybe only 20km/h...)
NP preparing new radical high aspect ratio foil sail for 2019.
he cut formula sail to test(6:40)
