V Twin

All boats will tip over sooner or later.
Small boats will tip over more frequently than large boats.
Un-ballasted boats will tip over more frequently than ballasted boats.
One of he major innovations of the 1960s was the self rescuing dinghy, which allowed the crew to continue sailing after a capsize.  At that time the hydrostatics of a dinghy when capsized became part of the designers prevue. But it hasn't really been given much attention.
V twin is an example of thinking half way through the problem.
This stuff really isn't rocket surgery.
IF you want the boat not to invert, it has to be stable in the attitude of  rig in the water. Stability requires the center of gravity to be aligned with the center of buoyancy.  In practical term, this requires the rig to float.  Most modern beach cats have sealed masts, which when combined with the over rotating wing mast is buoyant enough to prevent inversion. 
Some of my recent ICs have had sealed masts as a side benefit of  of getting rid of the main halyard, these boats are far less likely to go turtle than ones with big holes in the masthead.
I also designed very neat foam filled square heads for mainsails that may actually be better aerodynamically that a regular pin head but also have enough volume to prevent inversion.
Just mentioning it.
SHC

Originally posted by Owenfackrell Have you thought about doing a self tacking jib with control lines lead out onto the wings so that you can adjust it? this way you would only have to concentrate on the mian.

Edited by G.R.F. - 27 Apr 12 at 3:12pm

Originally posted by robinft Is there an entry point for air at the front end of the tunnel? I know that it's open at the aft end but I do wonder if there may be a slowing suction effect nonetheless.

Edited by G.R.F. - 27 Apr 12 at 2:29pm

Originally posted by Hector That 'rescue' boat is clearly the result of an overly optimistic committee! We have a 4.5m rib with 40hp and 5.5m rib with 50hp on our largish 1000' altitude windy reservoir. The smaller one is difficult when its very windy - certainly only really for use in dragging bodies out rather than aiding recovery of the dinghy itself . The 5.5m on the other hand  is just brilliant for gnarly days - can do anything we throw at it. It amazing how much difference 1m and 10hp makes. We did have a 5.5m open 'dory' type but that capsized when trying to turn in the waves near a leeward shore starting to tow a boat (caught sideways onto and so rolled by a wave). So we decided it wasn't up to the job and to get rid of it. Maybe Hythe want it?

Excellent Warts and all blog. Liked  this bit which considerably reinforces that you've succeeded at least in part with the entire point of the exercise :

Edited by Hector - 27 Apr 12 at 1:15pm