Need new prop for Merc !

ccarson2

Cadet
Joined
Jul 9, 2006
Messages
12
I have a 77 Reinell 190 tri-hull with Merc 888. We basically rebuilt the engine in the darned thing and it incidentally got warmed over by the installation of some new heads and cam.
It has a cleaver style prop on there that is absolutely horrendous for planing the boat (takes forever). I couldn't find any markings on the blades but maybe I'll take a better look. Here is a picture of the prop:
http://www.clevelandequipmentsales.com/ebay05/Boat/prop.jpg
After running it a few times the cavitation burns have become quite dark. And, to make matters worse, my buddy (who owns the truck we were towing with) managed to hit a building with the prop while turning around, bending one of the blades back about 1/2". So, time for a new prop.
The specs from the current prop as I recall them was about 5000 RPM and 47 mph. I almost certainly believe however that the tach is reading high and as soon as I get my hands on a digital unit from someone I will verify this - it tells me I am running 1100 rpms at idle and dialing it down so the gauge reads 600-800 makes the engine practically die.
The previous owner did claim that the boat would reach 55 mph, which I don't think is a lie since if I would have let it cruise at WOT it would have crept up there, but with the tach reading so high I didn't want to push the envelope.

What kind of prop should I shoot for, at least to try out for a baseline, since this prop is out of commission? I might be able to get a prop from Boater's world and return it after one run, or run my boat out to Chautauqua for the weekend to go to a decent prop shop...
I'm looking for good holeshot, easy planing and an intermediate top speed, 35-40mph?

Chris
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: Need new prop for Merc !

If your gearcase was half in, half out of the water, the clever might work......on an extremely fast boat.
We need a known prop with an accurate tach reading of that prop at WOT with a normal load to do you any good.
 

Crownie2

Petty Officer 1st Class
Joined
Jul 26, 2006
Messages
378
Re: Need new prop for Merc !

I agree - especially with the modified engine, there are just too many unknowns here.

Do you know what prop the previous owner used - that may be a start...

Bob
 
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