need higher rpm prop for lower HP motor

[evilwind1]

Hello IBOATS forum. I have a prop question. I just bought a 1993 Proline 192 that had a 115 Merc on it (threw a rod). I have a 90 HP Merc that was on a much lighter 18 ft boat . I put the 90HP on the Proline and it can't even get up on plane , and tach only reads about 4500 WOT. The Proline is a dual console and weighs about 2400lbs I believe. The prop size on the 90 is 13 25 x 17 is the # I'm reading.there is another # in front of it 992104. What size prop should I try to get higher RPMs. Or, should I just try to hunt down a 115 to power the boat? Thank you.

 

[steelespike]

Re: need higher rpm prop for lower HP motor

Dry weight is 2000 While the 17" probably isn't the ideal prop I feel it should plane the boat.
I do wonder why it won't plane at 4500 rpm.Does the motor trim down all the way.
I wonder if the boat may have absorbed water over the years from improper storage or care.
Were you lightly loaded in your test run?
I believe the boat is rated for 135 so at 90 your in the ball park again not ideal but workable.

 

[evilwind1]

Re: need higher rpm prop for lower HP motor

Dry weight is 2000 While the 17" probably isn't the ideal prop I feel it should plane the boat.
I do wonder why it won't plane at 4500 rpm.Does the motor trim down all the way.
I wonder if the boat may have absorbed water over the years from improper storage or care.
Were you lightly loaded in your test run?
I believe the boat is rated for 135 so at 90 your in the ball park again not ideal but workable.

I think there are 2 problems looking back: 1 trim pump is not properly working and the (very slow) and throttle cable needs adjusted for more throw. I gotta change the pump. Gotta get smart tabs and I believe a different prop to get it up on plane faster.

 

[evilwind1]

Re: need higher rpm prop for lower HP motor

also thanks for the help and info Steelespike!

 

[evilwind1]

Re: need higher rpm prop for lower HP motor

WHEW!! turns out just to be loose control cable latch near the motor. That was throwing everything off-shifting all wrong and throttle. We'll see what happens this next trip. Hopefully that little 90 hp will be enough for some light cruising/fishing locally in the LI sound this season. I'll be looking for a decent used 115 - 135 for next year.

 

[steelespike]

Re: need higher rpm prop for lower HP motor

I think there are 2 problems looking back: 1 trim pump is not properly working and the (very slow) and throttle cable needs adjusted for more throw. I gotta change the pump. Gotta get smart tabs and I believe a different prop to get it up on plane faster.

When you setup your smart tabs use only just enough pressurte to be effective.Too much trim tabs will lose speed and may plow
and waste fuel.