Recommended prop starting point

crawleym

Cadet
Joined
Sep 18, 2009
Messages
12
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1) Performance issue you are trying to correct.
Over revs at 5300 RPM. Recommended is 4200-4600 rpm. Current prop is pretty beat up.

2) Current prop manufacturer, model, aluminum or stainless and as a minimum.
Quicksilver Black Diamond Aluminum. 48-83282845-17p

3) Current prop diameter and pitch (required).
15" diameter, 17 pitch, 3 blades

4) Wide open throttle RPM and speed with an average load (very helpful)
5300 RPM, 44.5 MPH

5) Engine/drive make, model, year, and HP
Mercruiser 5.0LX 1995 205 at prop shaft according to manual

6) Boat make model, year, length and weight
1995 Bayliner 2050, weight is 2550 approx lbs according to booklet. Add 174 lbs of gas at ~28 gallons. Add 550 lbs for wife, 2 kids and myself. Total weight around 3274 lbs.

I want to stick with aluminum for the time being. Boat is used for wakeboarding and tubing. Elevation is mainly just a few hundred feet above sea level. Wondering what my best bet would be for trying next.

Any suggestions on where to start will be much appreciated.
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Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Recommended prop starting point

If you stick with the same make and model prop and change ONLY the pitch you can expect roughly 200 rpm drop per inch of increased pitch. So going from a 17 to a 19 should pull off about 400 rpm and perhaps even a bit more if the current prop is chewed up. That would put revs at 4900. A 21P would put revs at 4500. The 19P would be perfect for a heavy load and you could throttle back to stay at 4600. The 21P would probably be best overall if your average load is provided what you said it did with the other prop. With a heavy load however, you would not see the hole-shot performance that the 19 would provide.
 
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