Prop for Force 85

Its almost time to take the boat out, and I need a new prop.

I'm new to boating, never changed a prop nor do I know how to identify the one on there. Its a 1985 Bayliner Capri 16' with a 85 Force. What is the stock pitch, blade count, and spline setup? Should I stick with the stock setup? I mainly just cruise around with anywhere from 2-5 people onboard.

Any tips on finding a inexpensive prop? Id love a stainless one, as I bent my aluminum one out on the river last season. But I know they are expensive. Hoping to find a gently used one. I just need to know what to look for.

Re: Prop for Force 85

Look no farther than right here on iBoats. Click on the "Marine Store" button right under the iBoats.com logo at the top of this page. Scroll down to propellers. Enter the year, make and HP of your engine and they will list the various available prop. Look on the barrel of the prop for numbers. 12x17 means its a 12 inch diameter 17 pitch prop. If you see one that's 11-3/4 or 12-1/4x17P it would be ok to use. Diameter can vary a little. You should stay with the same pitch if you are satisfied with performance and the engine revs to it maximum recommended wide open throttle rpm with an average load. I guess I should point out the numbers I referenced are an example, and not necessarily what your engine currently has. There is also no "standard" prop because the manufacturer doesn't know whether the engine will be installed on a barge, pontoon, fast hull, work boat or what so its the selling dealer or boat manufacturer that packaged the engine made that decision.

Re: Prop for Force 85

Thanks! That helps a lot! But I think I want to go ahead and get a SS prop, and I diddnt see any listed.

Re: Prop for Force 85

Standard Michigan props. 15 splines 3 blade aluminum or stainless. Choice of 13 diam X 15 pitch, 13 X 17, 13 X 19, and 13 X 21.

Most likely your 85 will want a 13 X 17. But, since props are so variable, either determine what is on the engine now or find a loaner to test. You want that engine to be turning at the higher end of the 4500-5500 RPM range at wide open throttle under most usual load conditions.

Each increment change of 2 inch pitch will slow or raise the engine by about 400 RPM. So, for example, if the current prop was a 13 X 19 and the engine was turning 5000 RPM you could stay with that prop size OR drop down to a 13X 17 pitch and have the engine running at 5400 RPM with (probably) the same or slightly less (1-3mph) top speed.

Although stainless steel props turn slightly higher RPM in the same pitch, the Michigan stainless props are all cupped, so they turn about the same RPM as the uncupped aluminum props.

If you really want a stainless prop, they are definitely worth the extra money but keep looking on the auction sites for a used one. Be willing to pay up to 200 bucks for an EXCELLENT CONDITION used one. Be aware that repair costs for a poor one will be around 90-120 bucks--so be selective in what you decide to bid on.

Your '85 85 will use any prop that will fit a Chrysler 75 to 140 HP engine from 1980 on and any Force 85 to 150 from '84-'85 through '89-'90, so you have a lot of years to choose from. If they don't say, ask the seller if it is 15 splines and the diameter and pitch. Be aware that some stock props are listed as 13 3/8 inch X pitch--that's ok they are all interchangeable.

By the way: ALL Chrysler and Force stock props that I know of were made by Michigan but they had a different blade profile than the regular branded Michigan props.