bayliner 85hp prop size

[bipp]

I have a 1986 15" bayliner caprice with a 85hp Froce. The prop that is on it now is 13*19 prop. I am looking at getting another prop and I am being told that 13*15 is what should be on it. How will this effect my boat and will it do any damage to the engine?<br /><br /> Bipp

 

[superman]

Re: bayliner 85hp prop size

I would prop it to where the engine rpm maxes out at 5000 to 5200 rpms.

 

[bipp]

Re: bayliner 85hp prop size

Is there a web site to calculate or a formula for this?

 

[superman]

Re: bayliner 85hp prop size

Not to my knowledge. At that rpm you should get the best performance out of your engine. Keep in mind that the condition of your engine has a great deal to do with performance.

 

[93evinrude]

Re: bayliner 85hp prop size

What is the current rpm reading at full throttle?

 

[Ross J]

Re: bayliner 85hp prop size

Hey Bipp, I'm running an 85hp Johnson and the prop is 13 1/4" x 17 pitch. It works just fine for both speed and holeshot!<br />The main difference you;ll notice between 19 pitch and 15 pitch will be loss of top speed but a bueat holeshot to plane. There'll be great pick up when heavely laden or towing skiers, the downside will be top speed though.<br />Is it possible for you to borrow a couple of props at 17 pitch and 15 pitch and try them first? You don't say why you're changing in the first place! Is there a problem with what you've got now?<br />Ross

 

[Jango]

Re: bayliner 85hp prop size

Bipp, I have a 88, 85HP Force on a 17ft Bayliner. Turning a 13X15 Prop at 5200-5300 RPM and 35-37 MPH.<br /> Your boat is probably lighter and could go with a 17 pitch. Your RPM will probably be way to high with a 15 pitch. What is your top speed now?

 

[MGuckin]

Re: bayliner 85hp prop size

There are formulas that will get you close for max speed and ballpark pitch.<br />Alot depends on operating condition of motor and installation.<br />Need weight of loaded boat and hp to compute max. speed @ wot under ideal circumstances.<br />Need drive ratio & max. recc. rpm for motor to determine reference prop pitch. <br />Most companies recc. rpms are conservative: eg: omc says 4750-5250. They run great around 5800.<br />Not sure about Force.<br />I suspect it will end up being a 17" pitch with max top speed around 38.<br />I would not experiment with changing props unless you have a tach and motor is in good mechanical condition.