Reply With QuoteBasically, less blade area in the water = less resistance (drag) in the water = more speed.
For example, A turbine powered hydro runs a relatively small 2 blade prop. It spins it extremely fast, but it is two blades never the less. The reason is, these boats dont need any holeshot capabilities at all. They are all about high speed.
But, A V hulled boat, weighing in at say, 3400 pounds, with an at rest freeboard of around 2 feet would never get on plane with a 13 by 15 two blade prop.
most recreational boats need some assistance getting up on plane, hence the 3 blades. These also make for some powerful midrange acceleration due mostly to having more surface area in the water to push the boat. This becomes a disadvantage at higher speeds however due to the increased drag mentioned earlier.
It is at these higher speeds that a two blade prop has an advantage.
As for the 4 blades, they are a natural extension from the 3 blades, for the same reasons. They typically exhibit excellant holeshot and midrange qualities, but have slightly less top speed numbers than a comparable 3 blade. Conversly, although the 3 blade will have slightly better top speed, it will have a little less "punch" from the bottom on through the middle.
Hope this helps.
