The decision has finally been made. I'm starting a JR conversion of my 17ft trailer sailer, a finnish design Joe 17.
The boat has a displacement of about 500kg, a fixed shallow keel of about 100kg and a centerboard that lifts inside the keel giving a draft of 40-80 cm. (See the draft below).
I have done several modifications for the boat, and several more are on the way. They include changing the centerboard to steel and making it longer. I will cut a slot to the aft end of the fixed keel, so that the longer centerboard will fit. When in a raised position, I think this will give a "bonus" of adding directional stability when e.g. reaching. The steel centerboard will add 20-30 kg of ballast, and I might add a bit internal ballast as well (removable weights on the cabin floor).
Although the boat is small, I like to sail it in the coastal/open sea at the Botnian Bay and in heavier weather than most people think is too much for the size. But I have managed well so far with the bermudan rig, and the JR + added ballast + keel modification will most probably make this even easier :)
The boat has positive buoyancy, which is a big plus. At the same time this might be a problem when converting to JR, because one of the buyoyancy tanks is under the forepeak and I do not want to spoil it.
The mast will be installed with a tabernacle, because I want to keep the easy trailerability of the boat. I never leave the boat in the water.
I made the first sail draft with Arne Kvaerneland's Fröken Sörensen sail which I downscaled in Photoshop (below). That's why I don't have any measurements yet, but my impression is that the fit is quite nice. The original sail area of the Joe 17 is a bit over 15m2. I would like to get a couple of m2 more with JR. This first draft puts the CE of the JR right above the CE (estimated with the gravity method) of the Bermudan rig, and one reef would drop it almos excactly at the same spot.
I will be updating this thread, and all help and ideas are most appreciated, thank you!
Joe 17JR, draft #1.