new prop

[ironman3]

Hi all, I'm new here with a question that has probably already been answered. I have a Bayliner capri 1600 with a Force 90hp outboard. We use it for tubing and skiing. I need to change the prop because of damage. The numbers on the old prop is: 48 77348 A40 21P. The diameter is 14". Does this mean a 21 pitch? What would be the best prop for overall use, top end, or skiing?

 

[walleyehed]

Re: new prop

That's the original Merc P/N... and yes, it's a 21P.
The prop you want would be the one that puts you at the top of the recommended RPM range for towing...
What's the Rec. RPM and where are you at wide open throttle now, rpm-wise?

 

[ironman3]

Re: new prop

When I'm at full throttle it's about 4800 RPM. The red line is 5000.
We usually have (total) three adults and two kids under 50 lbs onboard. The top end speed now is about 40 mph. If i'm alone it will top out at about 45mph. With the old prop I had no trouble getting up skiing. I don't know a lot about props but I want to get the best one for my boat when I get the new one.
Thanks for your help. We love our boat!!!!!!!!

 

[walleyehed]

Re: new prop

If you want to stay with aluminum, you can choose between a Michigan Match, Michigan Vortex, or a quick Silver (Merc) match-up.
As for getting that extra 200-300RPM, which is where you want to be with a load, I would choose a new prop, install and test-run. I would then raise the engine on the transom, if it's mounted directly "on" the transom now,...I'd go up 1 hole and test. We should be able to run in the third set of holes from the top with no water pressure loss. Raising the engine does a couple of things...one, it lessens the gearcase in the water equaling less drag=more speed/rpm.
For towing, you may be under-propped for one-man operation, just don't let it go way over 5000 when you're alone.