I'm tiring to figure what the best prop for my boat is. I needed to get it replace and never have had to do this and the dealer wanted to give me a different one that was on it. I then called a different dealer and they told me a different size so now i'm really confused. Any help would be much appreciated. The #'s on the original prop are. 13.5 x 15R and it is a 3 blade. The first deal want to give me a 4 blade.