Can't Get WOT

[Reel Kahuna]

I bought a used 1991 Pro V 150 hp Yamaha with a 14-1/2 x 20 3 blade S/S prop. It came with the controls and OEM gauges. Seller took me on a test run then we removed the motor and associated parts.

I mounted the controls, guages and motor on my 20' Cuddy Beachcraft by Reinell that weighs 3K #.

On my shakedown cruise yestereday the best I could do is 3K rpm which the WOT should be about 5500 rpm. It didn't go up on plane.

I've read the "how to" in selecting a prop but I'd think the 2500 rpm is too much of a difference.

Any thoughts?

 

[180shabah]

Re: Can't Get WOT

What boat was this motor set up for?

Clearly you need to come down in pitch, but you are not trying to make up 2500rpm, just enough to get over your own bow wake. Do you have a prop dealer that will let you test a few before finalizing the deal? I would start with something in the 17-18" range and take it from there.

 

[cr2k]

Re: Can't Get WOT

I am betting that motor came off a bass boat with the 20 pitch prop.

With the hull and weight you are running you need much less pitch.

Is the engine mounted at the right height? Bottom of the cavitation plate even with the bottom of the hull.

 

[Reel Kahuna]

Re: Can't Get WOT

Thanks for your replies.

Yes the motor is off a Bass boat. Yes the cavitation plate is the right height. I'll check around for a 17 pitch prop and go from there.

Again thanks.

 

[45Auto]

Re: Can't Get WOT

Make sure you're getting full throttle, the timing is advancing correctly, shift disconnectors are adjusted properly, nothing's binding, etc.

How experienced are you at installing linkages on boats? Did you use a manual or just bolt everything together and go?

I'm not familiar with Yamahas, but on a Mercury there's lots of opportunities to easily screw something up when you're hooking up a throttle linkage.

 

[Reel Kahuna]

Re: Can't Get WOT

From the other boat I specifically removed the cables at both ends so that the adjustments weren't disturbed and reconnected them myself.

In preparation for my trip to the Columbia River Gorge in two weeks, I've scheduled the boat to go in the shop tomorrow to service the motor...impeller change, lower oil changed and a tune-up.

In the mean time, I'll check around for a prop that I can borrow for testing.

Thanks

 

[Reel Kahuna]

Re: Can't Get WOT

I went to the local prop shop that sold me a 17 pitch prop and said that if I need to go to a 15, they'd give me an even swap. Took the boat out to test but only hit 4900-5100 rpm WOT. I then exchanged the prop for a 15 and got 42 mph at 5600 rpm WOT. Now I can finally get back to fishing .

 

[steelespike]

Re: Can't Get WOT

That looks like a nice result.it sure helps when a shop will let you exchange a prop if necessary.

 

[180shabah]

Re: Can't Get WOT

..reel'em in...