Steve,

Try searching the US patent office site for human powered and the like. They abstract about 10 patents for boats. The Hobie system is based on one of these that is now in the public domain. I have used the hobie and it is quite fast. I prototyped an eel tail type but it was way too slow (even for fishing). I am going to try a Tuna tail type next time. Another possibility is "pump drive" Keep us posted on your progress.

Steve