Hypermiling boats (electric conversions?)
 

Has anyone done any work in an electric boat? It would be savign gas and pollution and would make a fun project

Darin has been messing around with replacing the motor on his sail boat. Thats the only conversion I know of.

hydrofoils can help reduce the wetted and frontal area in the water. Course a canoe and a trolling motor are pretty affordable and easy to hybrid (paddle) :)

I've enjoyed some time on a very high tech boat with a trolling motor auxilliary, and on both a regular canoe and a compact boat using trolling motors for main propulsion.
For efficient hull shapes, you just have to look back in history to the era of weak engines or oars.

There are solar/electric boats doing tours on Switzerland's Lake Geneva. This one runs out of Lausanne: Aquarel, ride on a solar boat - Official site of the City of Lausanne I believe there're also some running out of Evian les Bains, on the French side of the lake, though I haven't seen them myself.

There are a bunch of DIY electric boat motors on the EV Album.

Try: boat site:evalbum.com - Google Search

And of course non-nuclear submarines run on electricity when submerged.