Prop Diameter

[CKMK]

I have a choice between two Black Diamond 13.75 X 21 or 14.5 X 21 Alum. Propellers. What are pros and cons of the two. They are both the same price. The prop will be going on a 16' open bow with a Mercruser 120hp 2.5l Alpha 1. It will be replacing an old beatup 14 x 23 prop that isn't letting the motor get above 4100RPM (max RPM is 4200-4600 on the 2.5).

 

[Dhadley]

Re: Prop Diameter

The 13 3/4 is probably a 4 blade prop. The 14 1/2 is probably a 3 blade. Both good choices. <br /><br />Better check around on prices. Unless the aluminum prop is very very cheap there are ss props that are not much more money. There are some pretty good prices right here on iboats. Let me check something later today - email me at dhadley50@aol.com and use "props" as the subject.

 

[CKMK]

Re: Prop Diameter

Both are 3 blade. Is there a performance differance between the two?

 

[Dhadley]

Re: Prop Diameter

I would definately opt for the larger diameter on the larger gearcase if it were me. The smaller outboard gearcases can't use the bigger hubs. The large hub props usually have a diameter of 14 1/4 or more. Some large hub 4 blade props are 13 3/4" diameter. <br /><br />Some of the smaller gearcases use the 13 1/4" diameter and have smaller hubs.

 

[Bondo]

Re: Prop Diameter

Originally posted by CKMK:<br /> Both are 3 blade. Is there a performance differance between the two?

Ayuh,.....As Dhadley says,......<br />The Smaller 1 is an Outboard Prop,+ the Larger 1 is an I/O Prop...........<br /><br />Putting a Small Hubbed Outboard Prop on your Large gear cased I/O will cause Severe Cavitation,+ Blow-out.....