Best 19 pitch prop for 5.0 merc with alpha one

[DollarBoat]

Hey I am looking to get a little more top end speed out of my Sea Ray Express Cruiser 215 with a 5.0 Merc efi and alpha one. Right now I am doing about 30 mph at 3800 rpms. I was told I should look at getting a 19 pitch three blade stainless prop. Is this good for the setup of my boat? Any other recommendations? And what brand/models of props should I look for? Thanks.

 

[flyingscott]

What prop is on it now and you might want to check your tach or your motor is way over propped. I think the operating range of your motor should be up around 4800 rpm with that motor. I could be wrong but I would check that.

 

[DollarBoat]

It's the factory steel 17 pitch that's on there now.

 

[Yegboats]

Your WOT is 3800 rpm?

 

[DollarBoat]

Sorry no. My WOT is about 5,600.

 

[flyingscott]

Ok now you are way under propped as I am pretty sure the upper range for your motor is 4800 RPM. Check the tach and call the dealer see prop what they recommend.

 

[DollarBoat]

What diameter of propeller do you think I should get? Is a 14" the right size?

 

[steelespike]

This is like pulling teeth.What is the speed at 5600 ?
5600 is way too much. Calculates at 48 mph.?
Unfortunately speed at 3900 doesn't mean much.
If the prop is advertised for an Alpha One it should fit.

 

[steelespike]

Don't do a prop until you confirm your rpm we can estimate rpm from the gps speed at 5600.
Diameter changes with pitch as pitch goes up diameter goes down.I'm inclined to think a 17" at 14"diameter is likely not the right prop.

 

[theBrownskull]

If the RPM's are correct that is to high for that engine. It should be 4600-5000 range. What year is the boat and engine? Can you also list the gear ratio on the lower unit as well.