Here is my tow boat with electric motors. She is 55 pounds and very enjoyable to run.
http://www.youtube.com/watch?v=L4yJq5JBtRM
http://www.youtube.com/watch?v=shl7J0drIXQ
I also built a Krick Borkum and used the Cheddar Puffin veticle steam plant in it. I keep it in a case on display now. I have run it on the pond in the past.