Prop suggestion 1990 Wellcraft 18 Sport/Johnson 150 Faststrike

[Itsnotme1988]

Had my powerpack crap out on me the other day and while messing around with the motor I noticed the aluminum prop is a 14.25 x 21. I thought it was taking a bit to get on plane and thought it was odd that it would tach out at 4500rpm/42mph (with bimini top up,3/4 tank of fuel, and about 300-350lbs of people, haven't paid much attention otherwise) 4500rpm just seems awfully low for 2 stroke for some reason. I do not know the year of the motor but I'm thinking 92 from parts matching things online (it has no ID tag.)

So I'm looking for the best overall efficiency for my fishing boat. Weight from what I've seen in a 1989 brochure shows my combo at 2200lbs dry and it has a 52gallon fuel tank. 2 group 24 batteries mounted in the stern (will be moving to the under the helm.) I tend to do more midrange runs to cruise at best efficiency but still want a decent hole shot. Efficiency is most important.

Next season I will also be looking for a second prop to keep on hand for when we want to use it for tubing etc with light loads onboard (rated for 6 people but most likely never have more than 4)

 

[Chris1956]

A 19P prop will get you about 5000RPM, and maybe a bit more, due to being more in the power band.

 

[Sea Rider]

What's the min-max wot rpm range factory stated for that engine ?

Happy Boating

 

[Itsnotme1988]

I have no idea. Haven't been able find anything, especially since I'm not certain on the year or model

 

[jimmbo]

What rpm do you get when not running with the drag chute(bimini top) deployed?

 

[Sea Rider]

Need to find, know the correct wot range for that engine to maximize a prop and pitch to achieve top fun and water performance out of that combo.

Happy Boating

 

[Itsnotme1988]

What rpm do you get when not running with the drag chute(bimini top) deployed?

Right now the boat is down so I'm not 100% sure...think it was about 4700

 

[flyingscott]

5000-5500 is the range for that motor. You want to prop for close to 5500 with a light load.

 

[jimmbo]

Actually the WOT range for that engine is 4500 - 5500, but propping close to 5500 is a good plan. If you ALWAYS run your boat heavily loaded you would be better to prop accordingly. Right now you are running a 21, a 17 of the same brand of prop should get you pretty close to your target. BTW 1991 was the first year of the Faststrike, great engine, lots of low end torque

 

[Sea Rider]

It's better to run top wot rpm as usually loaded, in your particular case maximize a prop for 4 passengers for OB to run close or at max 5500 wot rpm.

Happy Boating