Matt,

There's all kinds of info available for modifying your kayak into a sailing trimaran. There are many guys who have done just that who would be happy to help you figure out the issues and arrive at a suitable solution for your interests.

One location, of which you can easily take advantage, is the Yahoo Group Sailing Canoes, where all manner of kayaks and canoes have been rigged for sailing in various configurations. Take the moment to join that group, announce your interest and see what comes from the members there. They also have tons of photos in their archive, complete with step by step illustrations of how the particular sailor/paddler went about their work.

There will be some issues you will need to more fully understand before going forward with the plan, but they are not insurmountable. The sailing will be the easy part once the boat balance, materials and layout have been sorted.

As for foil riding applications, such as seen on the Flyak, you are moving into a whole new realm of issues that have to do with all-up weight, sail area, or paddle power, ability to generate suitable power to engage the foils in their lifting mode and structure necessary to accept the forces generated by the foiling application (which is much different from the more simply solved, non-foiling sailing issues)

If you really wish to pursue the foiling potential, take the time to join the Boatdesign.net Forum and paw through the archives there. There's a wealth of info regarding sailing foiling craft of all sorts which could serve as a powerful source of inspiration, or intimidation, as the case may be.

I design and build multihull sailing canoes and kayaks and would be happy to help you in your pursuit if you choose to go in this direction. No charge for the help, I just want to see you having a great experience if you modify your boat.

There's a photo below of a sailing canoe I have done and here's a link to a Youtube video showing the same boat in the hands of the new owner, sailing at Utah's Lake Powell.

http://www.youtube.com/user/LunadaBay

The clip is titled: XCR at Lake Powell October '07. The other two clips are of a dual Mirage drive launch I did for a builder in Melbourne, Aus.