Help selecting a new prop

cmoreofjc

Recruit
Joined
Jun 24, 2013
Messages
1
I need a new prop because we hit a chunk of wood (at low rpm) and it now has a small vibration at low rpm. The current prop is smaller than what came on the boat. I am more interested in strong hole shot, easy planing and fuel economy at say 30 mph. Top speed isn't as important. Honestly this is my first lake boat so with that in mind - the hole shot seems strong with the current prop but it is obviously under propped.
The current prop is a 15x17 3-blade aluminum from Michigan Wheel
WOT is about 5200 and the tag on the motor says the range should be 4300 to 4600. Top speed with GPS is about 37 mph.
Engine is the original 1994 5.0 OMC Cobra - the title says it has 190 hp.
Boat is a 1994 Four Winns 190 Horizon, 20 ft. Somewhere I think I saw that the weight is about 2400 and then add 35 gallons of fuel, 6 passengers and stuff for a total weight of about 3600 - assuming that the empty weight is correct.

Please make a recommendation for a 3 blade prop and also a 4 blade prop. I will probably go back with an aluminum prop because of price but any input on stainless is welcome because I may find a used one. There is a lot of driftwood in the lake I go to so I don't know which type is going to be safer for my drivetrain.
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Help selecting a new prop

If you google "prop slip calculator" and select BAM marine's calculator; you can plug in your numbers and get an estimate of what sort of performance to expect from different prop pitches.

Any space you leave blank; click on "calculate" above the space and it will figure the answer for you.

Figure on 150-200 rpm per inch of pitch change.
 

Starcraft5834

Lieutenant Commander
Joined
Jun 2, 2013
Messages
1,677
Re: Help selecting a new prop

cmore... Ive got a 20ft cuddy, bout 2400lb boat also. smaller engine in 3.0 Mercruiser, 140hp.. I put a 4 blade Solas 15p- 14.75 inch, my WOT is 4500 at 32mph, that was with 5 adults in the boat.. hole shot with 4 blade was MUCH quicker, I hop up on plane in about 5 seconds, was about 4 times that long with 3 blade.. I'm a big advocate for heavier boats using 4 blade..
 
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