3 blade to 4 blade

[MSmith3615]

I have a 21ft cuddy with 350 magnum in it, I was thinking of going to a 4 blade prop but I can't seem to figure out what size I need. The prop I use know is a ss 14.25-dia 17 pitch. I was wondering what dia and pitch should the 4 blade prop should be?

 

[lenny2113]

Re: 3 blade to 4 blade

If your WOT is whithin 4400-4700 use the same size and pitch prop. <br />If it is not - every inch of pich down will increase RPM by 200. Reverse is true as well:<br />every inch of pich up will decrease RPM by 200.<br />14 1/4 x 17 pitch is what I use on my 350 Formula 26ft. WOT is 4600.

 

[MSmith3615]

Re: 3 blade to 4 blade

Do you use a 3 blade? I can't find a 4 blade with 14.25 diam and the pitches come in 16, 18, 20etc. Even numbers instead of odd? I get good perfomance out of 3 blade but people tell me 4 blade is better, is it? My wot is 4600.

 

[simidrm-45844]

Re: 3 blade to 4 blade

go to michigan wheel website and download there <br />catalog it's in adobe pdf it gives you a chart for determining the correct size and pitch of prop,but you need to know the size of boat and hp rating of motor and your wide open throttle(wot)but the chart will give you a good idel if your in the right area for size on prop,also piranha (www.piranha.com)has a composite plastic prop that the blades are removeable for 160.00<br />100.00 for hub and 20.00 for each blade x3<br />ind if you want to repitch just send the blades back undamaged and they will send you a different<br />pitch for free.