blade length

[gelee]

What would be the rpm difference between a 14.25 inch prop and a 14.75 inch prop,both at 21 pitch?

 

[Bifflefan]

Re: blade length

None

 

[Borchik]

Re: blade length

All depends on power and boat size, weight etc but likely around 100rpms.

 

[Dhadley]

Re: blade length

Actually the rpm difference will have more to do with blade design than diameter. Not all 21" pitch props are created equal so there could be a great deal of rpm difference. Or maybe no difference at all. It's impossible to say without a lot more info.

What 21" prop are you running now? Which larger diameter 21" prop are you looking at? What hull do you have? Jackplate? And so on.....

 

[steelespike]

Re: blade length

Usually diameter is a secondary consideration.In most applications pitch is the only consideration If the diameter varies closer to an inch then you might consider
diameter if you need to increase or decrease rpm 50 or 100 rpm not really necessary
if you realize a tach could be off that much.

 

[sethjon]

Re: blade length

You won't notice it, but make sure you have enough clearance for the bigger prop.