4 blade props vs 3 blade

[jmcii]

What is the performance difference between a 3 blade and 4 blade props? I have a 91 Barefoot Nautique and would like to know what the difference in performance is for barefooting?

[DanielC]

There are many different variables in propeller design. Pitch, diameter, cup, blade area, blade shape, rake, progressive pitch, hub diameter, material the propeller is made of, and many more.

Just because people can count to four, or even in some cases, five, does not mean number of blades is the most important parameter on a propeller.

If all other factors were equal, and they are not, a three blade would theoretically run slightly faster than a four blade.

[shag]

In my experience, you generally get a little more out of the hole power, and a bit less vibration. I noticed this more in turns. My .02

[TRBenj]

In my experience, you generally get a little more out of the hole power, and a bit less vibration. I noticed this more in turns. My .02

If talking about a 4-blade (as compared to a 3-blade), then that is consistent with certain applications... more so the larger/heavier ones. 4-blades are a little easier to balance and sport an extra blade (obviously) and a little more blade surface area... which explains the basic difference. Theyre also a touch slower up top than the 3's.

Like DanC said, there are a lot of other things to consider when comparing props... and blade count is only one of them. Complicating your choice is the fact that the 91-94 Excel/BFN is somewhat limited in prop to rudder clearance, unless youve had the shaft shortened. There is some good discussion on the topic over on correctcraftfan.com if you wander over there and poke around a bit.

[jmcii]

Thanks to all. I understand most of the differences in props. I was given a recommended 4 blade size equivalent to my 3 blade. I was interested purely in the performance comparison for barefooting. From your reports, it sounds as thought the investment in a 4 blade for my boat is not something I want to do. Thanks again.

[TRBenj]

Again, its not just about the blade count. Or diameter and pitch. Those are important, but not everything you need to know in order to compare them.

If the 4-blade in question was a modern CNC prop, its a totally apples to oranges comparison to the original 3-blade hand finished wheel. Of course, it may or may not be the best option for you, depending on how you use the boat...

So really, we have nowhere near enough information to be able to help you.