After several learning-curve evolutions, I finally managed to download & (somewhat) learn how to use Ross Leidy's Kayak Foundry program. You get a diagram that looks like this:
By moving points around, you change the shape of the kayak.
It kind of reminds me of when I used to order e-juice from E.C. Blend, put all my preferences in, and get a juice that tasted perfectly lousy. I have the ability to put in all the measurement that I think I want, and also make my own mistakes! "Tiny" changes will make a huge difference in the feel and performance.
Interesting feature: you can print out the forms scaled-down, for example 1/8 size, and make a scale model. I tried printing 1/6 scale, but the forms seemed too tiny to work with.
I also bought Rob Mack's' instruction manual for building his "Panache" kayak. In e-mails, he describes build on a "box beam" strongback, and I had to get the manual to see what he means. It looks like a long box girder made of plywood. I'm also considering, if the self-design becomes too scary, building another full-sized Outer Island. If the box-beam thing turns out to be a sweet & solid way of aligning the strongback, maybe I can avoid another blunder.
One of the cool things you can do with the kayak Foundry program is print the forms out at reduced scale, and build a scale model. I tried printing 1/8 scale, but found the forms to be too small to work with, so I tried 1/4 scale:
Ross did this for his RL-1. He went "all the way" in construction, even fiberglassing the hull, but I don't plan to be that fancy.
Actually, I found it harder to work with strips on a small scale, and I have shelved this project for now.
I tweaked the program around a little, and printed the forms at 1/4 scale. I made a slightly basic scale model, by milling some thin cedar strips and applying them to the forms. I didn't intend to build a pretty, "showpiece" scale model, like Ross, I just wanted to get a 3-D clue of what it would look like. I also re-posted the design on Kayak Foundry for comments. The comments reflected what I saw in the model.
My conclusion is that the scale model will look like a nice little kayak, but it doesn't really show much else.
I usually "start" a build by making some detail in advance, such as the carrying toggles. This time, I made the skeg trunk and control box. I had most of the necessary parts left over from the last build.
I was fairly satisfied with the design on the program, so I started printing forms. You can print them out on legal size paper, but you get a bunch of pieces that need to be taped together using registration marks. I investigated trying to export them somehow to a file that they might print at Staples, but someone on the message board said something about "distortion", so I thought it better to print at home. I started printing. The forms looked pretty small, and somehow unsatisfactory, so I compared the largest one to the O.I's largest form. The deck height was o.k, but it needed more slope to the sheerline, so back to tweaking.