Dont know what Prop I need-Please help

[nazz2005]

I have a 2000 celebrity BR 23' I/O mercruiser 5.7 250hp. Boat is tuned, bottom smooth, outdrive just painted 72 hrs ago. On flat water at WOT im maxing at 4k rpms. The engine cover and many people tell me i should be within the safe operating range of 4400-4800 RPM. Currently my prop is 3 blade alumn stammped 15x17P. What prop do i need to ge to at least 4400.

I have people telling me to go down in diamter stay same pitch...
also hear, stay same diameter drop pitch too 15 or 16...
Also heard get a bigger diameter stay same pitch...

*note that WOT is acheived at 3850 when i trim up it hits 4k* anymore trim and i slip...

A fellow boater told me i am "dragging the bow in water that i need to get the bow up after i plain out" i cant seem too starts slipping...thus need bigger dia prop...
Please help thanks a ton

 

[Islandbrah]

Re: Dont know what Prop I need-Please help

I have people telling me to go down in diamter stay same pitch...
also hear, stay same diameter drop pitch too 15 or 16...
Also heard get a bigger diameter stay same pitch...



Going down 1 degree of pitch will account for a 200 rpm rise. so if you are at 4000 drop 2-3 deg of pitch. If you were to get a larger diameter prop but stay the same pitch the rpms would actually drop because you will be spinning more surface area in the water. As for digging the bow get some trim tabs.

 

[Don S]

Re: Dont know what Prop I need-Please help

DO NOT change props yet !!!!!!!

Since you still don't have your engine running right, according to THIS THREAD you will just be wasting your time and money changing props to fit a poor running engine.

Fix the engine and your rpm will increase.

 

[nazz2005]

Re: Dont know what Prop I need-Please help

I did fix the engine, ITs all up to date i dont know what else to fix if anything?

Runs smooth- New plugs,wires,cap,rotor,battery,starter,oil,filter,fuel filter,all fluids, cooling system, paint, All oem mercruiser equipment.

 

[trendsetter240]

Re: Dont know what Prop I need-Please help

I did fix the engine, ITs all up to date i dont know what else to fix if anything?

Runs smooth- New plugs,wires,cap,rotor,battery,starter,oil,filter,fuel filter,all fluids, cooling system, paint, All oem mercruiser equipment.

Based upon the info you've given, and that your engine is in good tune, a 4-blade 15" pitch Solas Amita should put you around 4400rpm and help with the bow lift.

They sell them right here on Iboats. The link below is for the 5.7 Merc with Alpha 1 drive.

http://boatpropellers.iboats.com/Me...0-Pitch_Amita_1513-148-15_Propeller/769/9591/

 

[180shabah]

Re: Dont know what Prop I need-Please help

Have you compression tested the engine?
Have you weighed the boat and compared it to the specs when new?
What condition is the hull in? I don't care if it is shiny. Does it exhibit any hook or rocker?

 

[steelespike]

Re: Dont know what Prop I need-Please help

If you can't get the bow up by trimming I would suspect a hull problem
most likely a hook in the bottom probably back near the transom.Lay a 3 or 4ft straight edge along the bottom from the transom forward.The bottom should be in contact with the straight edge.