our Youtube short on the "system" we use aboard Guenevere. It's at;
http://youtu.be/WRCvPhTclqs

It's a full set of power topls that use one motor to drive them and all fit in a small dry box. The video is how I took an old dead battery and used it to add a cord to it. Now it's cordless when needed and 12 volt corded when needed.

The video is in 3D, but you can turn that off for easier viewing.

Greg