I had a 17ft aluminum boat and I can tell you right now that 45lbs will not be enough. If you are out in any kind of wind or waves, this will not do it for you. I'd look for a variable speed unit and something 65lb or above. 5 speed units are also an issue that I've had enough of. 4th and 5th setting are almost the same, 3,2,1 are weak. Variable will give you complete control over the speed.