Re: force 50 outboard
Welcome aboard ghayes. Let's see if we can be a little more helpful than just telling you to get rid of your outboard.

First, we need some deets. Based on the little you've told us your issue could be anything from a weak motor to a spun hub to toons full of water. What size barge? What are you basing your four to five mph estimate on? When you open the throttle all the way does the engine seem to be revving properly? Do you have a tachometer? Have you checked compression on the engine? Do you have a manual?