Oldmulti, thanks for the links, and sorry for the late reply. I got tied up removing the keel, but it's mostly done. I had seen your "Multihull Structure thoughts" but never noticed it was 331 pages long, that's quite a lot of posts I need to search through.
Lacking an exact design of what Jorg did, maybe I could just start out with a statement of requirements and go from there.
I'm looking for a trailer-able boat (not just a demountable in that I'd like to go from road to launch in ~1 hr). Looking for a total weight < ~3500lbs (boat, motor, gear, trailer). Looking for a coastal camp cruiser. Not looking for a racer, but I'd like something that can outsail a Catalina 22 in most points of sails and/or under motor, because if it can't noticeably outsail a Catalina 22 then why bother?
I'd also like it to be beach-able.
If I was starting from scratch, I'd probably be looking at a Wood's Janus or something similar, but by buying a used soling I get the sails, mast, trailer and hull for a lot less money, and less time to build (I think?).
My other motivation for a Soling is that the hull reaches 6' in width, which might allow for a "roomier" main hull and a smaller outrigger. True catamarans are normally a max of 4' wide per hull, which leaves 2 narrow hulls. Yes, you can build a central cuddy, but that adds more to the cost and build time. I'll probably end up with some kind of tent arrangement on the deck.
While my userid is SolingTri I'm actually leaning more towards a single outrigger tacking proa. The motivation being that it's one less hull to build/procure and the engineer complexities seem to be simpler with two hulls vs. 3. I have no intention whatsoever of ever trying to fly an ama/outrigger. Likely the outrigger will be larger (~2-4x or more?) in volume relative to the beach cat hulls that are normally used. The larger outrigger is there for more equipment storage, and to add more weight to help make sure it doesn't start flying. And if I can get the head in the other hull that's goodness too…
A single outrigger obviously needs to address issues with the outrigger being to windward and not blowing over. Many proas use some kind of a pod arrangement. I'm partly relying on the fact that the soling is 6' wide which makes it somewhat similar in width to the pods, but I also intend to "detune" the rig - i.e. cutting down the sails, or possibly moving the mast inwards on the forward beam.
To make it beach-able I'm thinking of a low aspect ratio keel on the main hull (say maybe ~10' long and 1' deep) and possibly a daggerboard on the AMA if that's not enough. That will also require doing something with the rudder as it would be deeper than the keel as is. Likely going to a stern mounted arrangement with a kick up rudder.
Pitchpoling is also a concern, so I'm leaning towards making the keel relatively narrow so it doesn't add substantial floatation amidships.
So it all seems plausible, though I'm just having my doubts on it all. If I got something that could motor to 10 knots (with a ~25hp enginer) and sail 8-10 knots beam reach on 15 knot winds I think I'd be elated. And if Jorg got to 18 knots with beach cat floats I'd hope 10 is attainable. Worst case I figured that if the Soling hull was a failure I could just build a Dierking style outrigger canoe using the mast, sails and outrigger that I now had..
Thoughts appreciated.
