I've got a 88' rude 15hp on a 14' alumacraft. If i am in the boat by myself it will run run like a top. With two peoplein the boat i can't run no more than 1/4 to 1/2 throttle then its like its spins the hub. I've check the prop its fine I've went as far as putting a roll pin through th prop into the hub. I know it isn't that any suggestions will be appreciated. Also it is a short shaft on a 15" transom.