I made a few changes to the parametric model of the hull, and then had the computer spend a couple of hours doing an optimization over a very board range of parameters. My goal was to find an even shorter hull capable of carrying the required load. The length-to-width ratio of the hull started coming down, the draft was increased slightly, and I ended up with a 6 meter hull capable of supporting 700 kilograms, which would be adequate for single-handed coastal hopping.
I also went through the mass and cost numbers for the boat. My best estimate is about 5000€ to get this boat ready to go (since I already have the ama built and quite a lot of epoxy in storage). Ontop of the cost of the boat, there is the potential cost of a workshop, which provided I can actually find one sufficiently close to me for regular work, would cost on the order of 100-150€ a month. Over say 18 months that adds up to another 2000-3000€. Looking at the ~9000€ needed to complete a 9.2m boat, that would make for a cost of 12000€. That is a sum of money which I absolutely do not have, and couldn’t even come close to racking up with a student job on the side.. The 6m boat on the other hand could be built in my garage, by building the middle 5.5 meters of it and gluing or bolting on two 25cm end-pieces, right at the end.
Figuring out how to support the rig on such a tiny hull proved tricky, but of the 4 available options, a supporting strut on the windward side, is the easiest to build and to operate. KISS. An even simpler and cheaper solution would a traditional Polynesian crab claw rig, but reefing is a bit of an issue, and with a lofty Hobie 16 mast I can get a heck of a lot more sail area on the boat than with a single crab claw sail. I’m going to need a bowsprit for that gennaker though… 🙂
Giving up loads of interior space and comfort doesn’t bother me so much, but with the reduction in length you take a massive loss in seaworthiness. While the maximum speeds of either design probably would not be that far apart, the average speed of the boat will also suffer significantly, even more so because the average number of hours where the boat is moving forward will also be less, on account of more in-port days (heavy weather) and I figure getting such a small boat to sail by itself under autopilot would likely be quite a challenge, at this size it’s more of a beach-catamaran than anything else. All that said, there’d be little sense in trying to build a boat I can’t afford, and if anything, the smaller boat would promise a real adventure!