Prop selection

bspeth

Senior Chief Petty Officer
Joined
Aug 30, 2013
Messages
758
My purpose of prop change is damage to my old one and fine tuning. Current prop Michigan wheel 15.25x15 3 blade aluminum.84 beachcraft funrunner 18.5.Approx weight 24-2600 lbs. Merc 229 3.8l v6. 185hp.WOT at 5000 ft was 4400 and about 31 mph on the dash gage.Trim full down position.I would like to run about 4600 rpm but I also frequently run above 6000 ft also. Please advise.If I need two props the that's fine.Thanks-Blair
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Prop selection

You should be trimming up for best rpm and speed.We can't accurately eval;uate your present setup if your runnung trimmed all the weay down.While slow by normal standards for 5000 it seems reasonable.Your slip calculates at about 9%.
Pretty good for not being trimmed up.Your power is down about 15% at 5000,would be about 18% at 6000 ft.
If you want 4600 a 1" reduction in pitch may help. While it should give the boat a little more pep the top end may be less.
Would be better if we had your numbers lightly loaded and trimmed up.
 
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