Pencil and paper is almost quicker for me, but all the best inventions do start in MSpaint..
It's all quite obvious in hindsight, two foils pulling directly against each other, and gravity (or mast base pressure) is never needed to keep the thing in control..
Could SR be finally Flying The Fin?!? Even though the fin is trying to pull everything under water.. Maybe Sinking The Fin..
I doubt windsurfers could adapt this but using a Kite is interesting..
That front float on the SR is needed for stability, and probably has as much drag as a windsurfer (the spray out the back is nuts), but the thing has enough horsepower to compensate. The trick would be to reduce the size of the concept while finding a way to control the thing with minimal drag.. Gyroscopes and magnets and penguins.
Looks like 70 knots is on their hit list.
forums.sailinganarchy.com/index.php?/topic/140038-vestas-sailrocket/
At these speeds, people are going to start risking their lives to push the limit, men have died b4 in the quest for speed supremacy, hope I'm very very wrong in this, coz I know the urge to be the fastest, will mean pushing the limits, and blocking out potential consequences. No speed records would ever be broken if people didnt push the limits and abandon the thoughts of consequences.
I seem to have read in amazement hydro theories but never got to see anyone reply about fin or skeg cavitation as mentioned in the past when the speedsters were barely over 40kts. and now that it's nearing 70 is there any bearing to this and wow am stuck at 28 for the 500 
The question of foil cavitation is fascinating in the light of Sailrocket2's record. I had assumed they were running some sort of super-cavitating foil, but the words written by Paul seem to suggest that they are using a conventional foil. He talks about the question of where it's cavitation limit is.
So if they are using a conventional foil, how is it that it has not encountered cavitation yet?
And if it has, how is it that SR2 can still go faster in control?
That's exactly what I was saying to someone on the weekend Daffy. I remember speaking to you and Matt about it last year and this piqued my interest once I read the same info you did. Will be really interesting to see how they have got around it or if in fact the cavitation just isn't as much of a problem as it might have been!
Sail Rocket hit a cealing at 52 knots with their old boat / foils due to cavitation. Sail Rocket 2's foil was designed to cavitate from 65 knots. Looks like it may be a little higher in practice. They mentioned in one of their blogs that the foil received dome pitting from cavitation at the top end of the run.
http://clarksail.com/2012/11/25/the-word-from-paul-larsen-after-sailrockets-big-day/
Worth going to
newatlas.com/new-world-speed-sailing-record-6537kts-75mph-121kmh/25065/
for 139 great speed sailing photographs like these.
More great insight from Paul Larsen here: http://clarksail.com/2012/11/27/the-real-reason-why-sailrocket-is-special/
It seems that somehow, the Sailrocket team has found a way to delay cavitation to a much higher speed than what some of the theories have predicted in the past.
Please allow me to ramble a bit. Just thinking out loud really. I could be way off.
I can speculate as to what they might have done. In theory, to delay cavitation you have to reduce the peak load on the foil so that the low pressure side does not get vaporization (boiling). I can also speculate about some ways on how to do this.
-Use a larger foil to reduce the lift per unit area. (but increases drag)
-Use a longer chord, lower aspect. (but reduces lift to drag ratio)
-Design the foil section to have a more even lift spread over the whole section, rather than concentrated on one part. (I am sure there could be any number of negative effects of this but I don't know enough to comment further)
-reduce the angle of attack and total load on the fin (Windsurfers may do this to some extent by sailing broader, but SR2 is sailing quite a tight angle in comparison)
I am sure there are others and someone will add to this list.
Note that all these directions have been tried in windsurfer speed fins and are currently evident to some degree on the fins used by the fastest windsurfers.
The problem as I see it, is that much of this is theory. The computer programs that designers use to predict cavitation of different foils are not absolute. They are based on best knowledge, but that is not absolute. There seems to be a large number of variables that the programs can not always accurately predict. Its the old computer truism again: The data out is only as good as the data in.
The fascinating thing about Sailrocket is that it seems to have added a significant new chapter to the book. I can't wait to read that book.
On the other hand, when Hydropter did it's thing and amazed us all a couple of years ago, we had a similar conversation. Mal Wrights take on it was that, perhaps there was significant cavitation happening, but that Hydropter could develop so much power it could overcome the extra drag and still go faster. Perhaps this is part of the equation with SR2 as well?
