hilly said..
Blame Laird

lairdstandup.com/products/surrator-1

kobo said..
Having said that , It would be good to have some type of science based assessment for foils

colas said..




The thing is that how to judge the measurements (the "evaluation function") is tricky.

For instance, if something adds 5% drag, but prevents stalling or breaching by 5%, the real life benefit for a foiler may be night and day, because stalling will abruptly end your ride in a potentially dangerous crash, while you may not even notice the 5% added drag. One 5% will ruin your session, and the other won't.

colas said..




The thing is that how to judge the measurements (the "evaluation function") is tricky.

For instance, if something adds 5% drag, but prevents stalling or breaching by 5%, the real life benefit for a foiler may be night and day, because stalling will abruptly end your ride in a potentially dangerous crash, while you may not even notice the 5% added drag. One 5% will ruin your session, and the other won't.

kobo said..

A little off topic but, do you know about the difference between a sanded finish vs a gloss finish in regard to foil performance ?

kobo said..
Thanks Colas, I knew you would have the info , Interesting most foils are sanded finish but not all, gofoils are all gloss now.

colas said..


For a foil I would guess you could feel things better in situations where a bit less drag can mean the difference between success and failure. Dockstarts? Pumping?

juandesooka said..
Colas: one of the very subtle testing areas could be light wind wing foiling. It is such a thin line between madly pumping vs getting unstuck and flying. I've found one strand of seagrass can be enough drag to make it impossible. So maybe the 2.56549% improvement would be felt there?

In my sailing days, I used to use a hydrophobic compound on my dinghy hull (think Rain-X). It made a difference when trying to get the hull to break free from the grip of the water and on to the plane. I could get planing a couple of knots boat speed lower than my competitors and therefore exploit the advantage. It does work.

For foiling, I think it would work in the opposite way. Generally, due to the high and low pressure surfaces of the mast and wings, you have a different set of problems if using a hydrophobic copound. We sand the mast and wings to create a rough texture to make the water "stick to the surface". This prevents ventilation.

The race guys will have a cow if you even touch their wings or mast due to the fear of sunscreen on the fingers which will create a hydrophobic barrier on the surface which leads to ventilation. The wings come glossy but usually get sanded. Front third of the wing/mast with 1200 wet and dry and 400 for the back 2/3rds. The rougher texture creates a better bond with the water. Water on water friction is less than water of solid polished surface.

Many off shore race yachts have a textured finish on the hull to create that boundary layer of water to promote the water on water friction.

Don't put hydrophobic coatings on your foils!!

Hdip said..
What's the wingspan on the Kujira 980? Similar in width to your 1300? Or is it much wider?