Spy photos

Yes your right Ben, but those losses on the tips do move down the foil section. Agreed it does get less - but if your looking for the "best" performance then youd wana reduce as much drag as possible - why else do people spend hours fairing their foils for just a little nik............. drag, even the smallest amount can then cause cavitation.

Every little bit helps I guess

Aircraft that turn don't have winglets?

Err - wrong! Look at gliders - where winglets were first developed.... Mine has winglets and climbs (in circles) and cruises in a straight line better than one without. I'm not an engineer but simply put, there is less drag with them fitted. Don't think I've ever had more 'thrust' through having them fitted either....

At what point of sailing, would you consider that there was not flow almost directly over the rudder? If the water was not flowing over a foiling moth's blades, it wouldn't be able to turn at all and stay up.......

Yes but no but.....

How can a passive object 'create' thrust? No-one has ever achieved that? I still don't see it as a driving force, more a way of reducing drag therefore allowing the thrust created from the sail to be used more efficiently.

Whatever - we're splitting hairs here. I think it's a great idea to try and would love to know on what the winglets were based on, how a design was finalized and then what performance advantage they give. Also wondering why the adjustable centerboard stops them from being used there? In my simple mind, if you can reduce drag, you can use a reduced AOA therefore the same foil shape could go faster? What effect does the AOA have on the winglets compared to the foil?

I'll certainly be having a look at that moth next time it's drawn to the cheese candle. Hope I actually get to see it sail this time.....

I know - I was out in a 200. Some foiling towards the end of the day though....