I was going for run time because the lake is about 3 miles long and I wanted to make sure that I could get the boat back without having to use a crash boat to retrieve it. There are lots of good batteries around. I was limited because my system is for 12 volts so I was stuck with lead acid gell cells (3.5 - 5 lbs each) or NmH D cells packs ( 2.5 lbs with high discharge rate). I chose the NmH packs because I budgeted about $1K to build this boat. I have just complete building the hull and powering it for about $500. The rest is for building and powering the torpedos, roll off racks, and bb cannons in a manner which looks scale. I suspect that I will be doing my water trials in about 3 weeks. It will take me into the spring to finish the other features but it is a lot of fun especially when the boat looks like and acts like the real thing. I have cooling coils installed on the motors, speed controls, and battery packs.