: One of the reasons I went with a gaff rig.

: All that sail area is needed to get the foil "out of the hole"

: Take a look at a Windrider Rave

: Specifications
: Length 17' / 5.2 m
: Beam (foil tip to foil tip) 17'/ 5.2 m
: Beam on Trailer 7'6" / 2.3 m
: Weight (total) 400 lbs. / 182 kg
: Mast Height 25' / 7.6 m
: Total Sail Area 195 sq ft. / 18 m2
: Addl. Sail Area w/
: Optional Reacher +97 sq ft. / +9 m2
: Draft (foils up) 1' / .3 m
: Draft (foils down) 4' / 1.2 m
: Capacity 400 lbs. / 182 kg

I've owned and sailed both gaff rigs and marconi rigs, you can discount probably 40% of the sail area of the gaff rig boat, the head of the sail will fall off to leeward providing little if any additional drive. Also they work ok on fairly slow beamy monohull boats, they don't work well on fast boats since the apparent wind goes forward with speed and the gaffer is at it's worst upwind. Fast trimarans always sail upwind. Also a ketch rig is at it's worst upwind, the fore sail interferes with the wind going to the after sail so it loses a portion of it's drive.

Not an expert by any means on hydrofoils but have followed their developement for many years. Seem they are more efficient with small foils but those also need high power to lift. A larger foil will lift more easily but causes more drag on the top end. I'd look at larger foils since the top end likely isn't achievable anyway. Biggest problem is angle of attack of the foils, Hobie's settup works good on the trifoiler. The early hydrofoil sailing boats would stay on the foils at best for a minute or two before crashing back into the water. Btw, if you can't get the boat up out of the water on the foils they cause gross amounts of extra drag and slow the boat to almost nothing for forward speed.

Still the concept is interesting

Bill H.