PeterP said..
Thanks, Greg, very good info. Couple more questions - what do you currently use as your lightwind dwd foil and would you agree with following assessment - As a rule of thumb, foils larger than 1500sqcm have too much induced drag to enable sustained pump and glide irrespective of body weight? Larger foils will be easier to get up on foil (than 1500 and down) but at the expense of too much drag for long sustained bump riding?
I'm 1m70/75kg, my biggest foil is the Kuira 1440 with 220 stab, this is the one I use when it is light (under 15nd).
Then I have Axis Art 1099 and 999 when it is 15nd +.
I also have Unifoil Hyper 190/170/150 but lately I've been trying the Axis art.
For the last few weeks I've been using only 75cm mast, I used to have 82cm but I think 75cm works best (easier to get up, stiffer, more control).
I think what matters most when it comes to efficency is the ratio wing span/cord more than surface area. Also it depends on conditions.
For exemple a heavier guy can be faster than a ligher foiler using a smaller (supposely faster foil) especially on big days.
One thing I know for sure is, it is better to fly non stop slow than struggling trying to keep up to fly fast and having to stop.
Axis 1150 is a good example, probably one of the easiest foil to fly on small bumps, it might be not super fast but anyway on a slow run you will go slow anyway. So then it is all about compromise, for example Axis 1050 (1500cm2)/Kujira 14440 can be a good choice for lighter riders.