I talked to John about X it. He liked it and it worked well for deep downwind sailing. But I wouldn't want one. It was fast, but it was very big and incredibly thin hulled - you can't point to the rig as the reason it sped along.
After spending over 15 years getting patents and making very innovative catamarans (my hands have paint
on them right now because of working on the small cat) I would warn anyone from doing large innovations without huge experience. There is a reason most people don't do something brand new - it is because it probably doesn't work
. Small progressions are fine, but massive changes are fraught with bad potential.
The OP mentions that headsails are more efficient - but they are not. If fact large genoas are very inefficient - which is why they are rarely seen on racing
boats, and never on fast multis - reachers and screechers for downwind, but when the wind
blows up, short overlap headsails and mains are all you see.
The plan form for a genoa is a triangle which is about the worst shape in aerodynamics. Then you have headstay sag, which on this rig will be increased. And with no main to increase foreasty tension the sag will be even greater. Also both rigs require a mast, but the effects on the main are small and the main saiplan can be elliptical or even square top increasing main efficiency and reducing parasitic drag. The mast will not sag to leeward in gusts, like a forestay and the main can even depower itself in gusts, whereas a genoa, especially a large one just gets fuller when you don't want it to.
Mast aft rigs were introduced by Prout decades ago and slowly they morphed into more normal rigs. Problems with reefing mains downwind can be overcome by getting rid of spreaders (use a 3 stay a side rig) and putting nice slides on. Going upwind without a main is pretty hard to do, getting sufficient forestay tension on mast aft rig is hard because of the larger J measurement compared to the aft sweep of the shrouds. So by going large with the genoa you reduce the effectiveness of the genoa itself. I was on board a 40ft cat with an aftish mast rig the other day (it had a main). The forestay was pretty loose but the shrouds were very tight. It is impossible to get high tension on the forestay (without overloading the shrouds) because of simple trigonometry unless you over engineer
the mast and shrouds.
Also our boats are not fast enough to do without the beneficial interaction of main and jib
upwind or reaching.
As for problems with chafe - I still have my original 21 year old main and altough it needs replacing sometime soon, it is in nice shape and free from chafe. Chafe is not a reason to totally change the rig.
I guess that my words of warning will not be heeded. When I came up with my new cat design 20 years ago, no one could have talked me out of it. I had been around multis for 18 years and had sailed lots of different boats. Same with all the innovations in my larger cat. Most of the major innovations have been removed from the large cat, and if I could go back in time and slap myself in the head
and say "Don't build crazy new things, just refine a little" I would jump at the chance. There is so much work in getting something custom built, getting it wrong and redoing it, over and over again.
I had so much eagerness to try something new. It cost me huge amounts of time and lots of money
. My advice
for the OP is to drop the rig innovation. Or at least try it on a small cat, or talk to John Hitch, he is very approachable, or do lots of sailing on a range of cats. Most new innovations are silly, and waste money
. Most working innovations have been done before - my wishbone is old tech, as is the three stay a side rig and the pivoting engine
pods. I just refined them slightly to make them work better.
John Hitch drew an amazing new structure for his boat Wired in the 80s. He got an old beach cat and tried it out on this test bed
(Flight of Fancy) first. Adrian Rogers wanted to make a fast cat schooner - he made a small version first to prove it (He then built Shotover 2 and it was super fast). These guys really knew their stuff, had built many boats before, were already legends in Oz multis and still they built small test versions before they went full size. To do otherwise is to risk huge amounts of timer and money.