Let me check my boat and see how heavy mine are I am no expert in these feilds but I do have a dinghy that probably weighs 100lbs and have run that one out within a few hours if just running a trolling motor all the time. I am guessing your plontoon weighs close to 100lbs + the weight of you and your gear? You may want to check with this sublect with some guy's who are experts I dont want you to end up buying the wrong stuff because of me. But for a trolling motor I think you should get this one it is designed for smaller crafts and it has teh shortest shaft avalible http://www.cabelas.com/cabelas/en/templates/links/link.jhtml;