Da brauchen wir doch gar keine Theorie!
Dr. Zak hat uns doch alle darüber aufgeklärt, daß der einzelne Flügel unten an der Finne absolut perfekt ist.
Und nun doch 2 Flügel?????
Also mal ganz ehrlich: die Idee mit der Y-Finne und 2 Flügeln halte ich für ganz brauchbar, die Position des vorderen und des hinteren Flügels stimmen mit den herkömmlichen Foiltypen überein.
Da könnte man aber auch einen "normalen" Foil nehmen und an einen 50 cm "Mast" schrauben. Problem werden die 50 cm sein, da ist der normale Aufbau mit evtl variabler Mastlänge bis
100 cm viel besser.
Dr. Spin Out
It may be little difficult for a beginner to use 100cm mast in waters less then 100 cm deep. When tide is high in my location I use a longer mast. But I still need to walk for long way in water in order to start at enough depth.
The most popular windsurfing and kite spots in the USA are very shallow. Sometimes it gets under 50 cm deep for miles. You do not see any foilers there but the spot are very nice. With shorter mast it makes it possible to foil on these popular spots. This is the reason why two legged design could be an advantage because it makes it possible to spread the main wing and the stabilizer at a grater distance for significant stability increase. You may want more stability with shorter mast in order to hold your altitude more precise. Longer fuselage adds stability too but at a higher cost of drag: more total area of parts under water. Also, long fuselage becomes too flexible as you can see on this video:
I personalty find it much better to foil on a stiff design.
Besides, you need a wider board for a longer mast. Wider boards are popular anywhere but not in the US. In my area we ride 70-90 liter boards. I think it is because you can start it easy anywhere on under 1 meter deep water. Water start is often easy because we have winds and warm waters almost year round. Smaller boards fit into a regular small size car. 100cm mast does not work on my 60cm wide board. 50 cm mast work well on my 60cm width board.
When I go windsurfing I take foil as a backup to use it if I do not have enough wind. If I used 100cm mast I would need to bring a wide board. Wide board does not fin inside my car so I have to put it on the top of my car and I need to watch it so it does not explode from air pressure getting hot under sunlight. Even when I am lucky to have enough water depth for 100 cm there is sea grass on the bottom. Shorter mast does not get as mush sea grass as 100 cm.
In my practical windsurfing routine the only reason when I want a longer mast is when I go to another spot like ocean or open bay where we often have waves. But I still like 75 cm mast more compare to 100 mast.
I agree that all the designs have advantages and disadvantages that can be discussed theoretically. However, when it comes to practical every day using of different designs you find out that the every day conveniences may dominate over the theoretical conclusions in front of the computer screen at home.