Correct Prop?

Another question from a nubbie. I have a 16' aluminum star craft with a 50 horse merc with hydralic trim. Boat has open bow with a deck, one 6 gallon tank, electric trolling motor up front, and a portable 12 gallon live well. Seems to me this a light load. The boat came with 2 props. 3 blade aluminum with markings 4873134A12P and a 4 blade composite with markings 4 x 10 x 13 / 4 x 254 x 330. The engine runs great revs fine but takes forever and a day to plane out. Doesnt matter where the engine is trimmed to, still takes forever. Can anyone tell me if the before mentioned props are even close to being correct for this application?

Re: Correct Prop?

ddrieck said:

The engine runs great revs fine but takes forever and a day to plane out.

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Does it do this with both props or which one? What are your current WOT RPMs. What is your WOT MPH?

Re: Correct Prop?

Same with both props. 5000 RPM @ 30 mph + or - a few as I'm reading off the speedo and not GPS. Could someone have changed to prop that is wrong dia and pitch. I just bought the boat and have had it out twice.

Re: Correct Prop?

To answer your question -- yes, those props are in the ballpark for your engine/boat combination. A 13P prop is fairly standard on a boat that size with a 50 HP Merc with a 1.83:1 gearcase. The fact that it's a four blade composite might be a bit much although the speed and RPM are right for the combination. The 12P should get that rig out of the hole pretty good though and it should also allow higher engine rpm. Compsite props tend to have a fair amount of blade flex so it might be acting more like a 12 than a 13. You might want to check the position of the AV plate in relation to the bottom of the boat. Ideally it should be flush to an inch or two above the keel so you may need to raise the engine a hole or two. I would also check engine compression as it may not be performing up to par. An engine with low compression will seem to run well but it simply cannot develop full power.