What kind of boat? Generally four blades handle a little better and have better load carrying ability and three blades are a touch faster on top end. But even these characteristics aren't 100%.it seems like most of the heavier boats like stratos, ranger, triton, etc are now running three blades and bullets and allisons run four blades to make them a little easier to drive. I have an Allison and run a pro et four blade and it is an excellent prop for handling, acceleration, load carrying, and speed.
