Hello Tugwash
Welcome to the madhouse, if you do a search for Tyne Tugs Marlene it should take you to the build thread of my Marlene, since building her i've changed the motors to MFA 500 geared 6-1 a bit noisy but plenty of power for towing etc i found that a 12v 3amp battery fits a treat and gives a couple of hours decent sailing.
Dave