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  1. #1

    Default 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    My goal is to figure out which pitch on a prop is the best for my boat between 15, 17 an 19.

    I am a complete novice to boats having bought a 1987 17 ft Bayliner Capri with a Force 85 HP (model 356X7A) motor last Fall because I wanted a boat, the price was right and the owner babied the boat. Anyhow, I want to get a new prop and everyone I talk to has a differenet opinion. The boat has no tach so I have no idea what the RPM or speed is with a WOT. The tag on the motor say it ranges from 4500 - 5500 RPM. The engine has been rebuilt and the old owner says it should have 90 HP now, if that matters at all. I had the boat on the water in September and it seemed to run fine, but keep in mind with my experience I don't really know what fine is and how a boat should respond.

    Two props came with the boat and they are roughly 13" in diameter. The prop that was on the boat only has these numbers on it A623265 and PS623. The spare prop has these two numbers on it A825285 and PS625. In searching the best that I could come up with is that they are Propco props with the PS623 being 13.25 x 17 and the PS625 being 13 x 19, if I am right on these assumptions. My dilemna is that most places I spoke to about props are recommending a 15 pitch prop. Which is the safest route to take. I am fairly certain that 19 is not the answer.


    On a side note, if anyone can help me find a Teleflex 53743P Tach so I can add that to my boat, that would be great as well. Being 20 pole makes it tough to get a tach on it.

    Thanks

  2. #2

    Cool Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    Yes, i have a very nice new Teleflex Tachometer 53743p in my hands here right this moment. I am returning it to a dealer ... where it will sit forever. I will be glad to give you their name and phone.

    30 to 35 bucks is the price I believe.

    This tach is for a "Force 20 pole" .

    Steve
    EDIT
    Last edited by JB; November 27th, 2010 at 08:35 AM. Reason: Email violation

  3. #3
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    17 pitch is probably the best estimate without a tach. I am almost certain that 15 pitch will be too little and will cost you speed. It would be good for water skiing, but for tubing, the 17 will be correct. For the 85 on a 17 foot boat, 19 pitch will be too high.

  4. #4
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    i have an 1988 16 foot bayliner/trophy Center console.. with an 85 hp force and i run the 13x17 and my engine rpm wot is 5000 5100 and a top speed of 35 mph... My boat planes out well and cruises nice at top speed... the only thing i wanna change is go from aluminum to stainless with the same pitch im not sure it will help or hurt me...

  5. #5
    Fleet Admiral jerryjerry05's Avatar
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    The 17P is what you need till you can put a tach on it.
    The 15 won't work!!!
    If your boat is set up for a 17 a 19 will cost more to run.About 10-20% more fuel usage.You might go faster but at a cost.
    If you want to use stainless and a 17Aluminum is what's needed now. You need a 15p Stainless.
    5500rpm is OPTIMUM!! With the correct load:1/2 tank fuel/1-2 people and equipment.
    You need a tach.Anything else is using the WAG system(wild *** guess).J

  6. #6
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    I used to think mine had a 13x19 but I was mistaken. Tinkering around in the shed I see the lonely prop just sitting there on the ground and I just had to check and make sure. Turned out it was a 13 1/8thx15 aluminum. Michigan 072055 is what the number was. 1986 85hp force on a 15' capri bowrider.

  7. #7
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    I have a Bayliner Capri 1600 project boat with a Force 85. The 17 pitch is common on this boat and will perform well for the type of boating it's aimed at. That is, cruising around and maybe pulling a skier now and then. A 19 pitch will likely be a little too much. I have my 1983 Force 85 on a 1972 Glastron GT-150 right now and changed to the 19 pitch prop since it is smaller, lighter and designed to go fast. It'll do about 41 on it. Expect about 35mph on the Capri with the 17 pitch.

    Marty
    http://www.martyhammersmith.com

  8. #8
    Vice Admiral NYBo's Avatar
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    My '88 version of your boat came with a 17.
    Bob
    '88 Bayliner 1700 Capri Bowrider, 85 HP Force O/B, "Sea Weasel"
    Want a vessel safety check? Click here. Want to join the Coast Guard Auxiliary? Click here.
    Disclaimer: Although I am a member of the USCG Auxiliary, the opinions and advice in my replies are my own and do not necessarily reflect CG or CG Auxiliary policy or regulations unless so specified.

  9. #9
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    Philly try a piranha prop. They have a hubb kit for around $80 and each blade is only $20. A prop kit is $139 I think but the good thing is you can get 3 blades of 15 pitch for skiing and you can buy another set of blades for $60 in a different pitch. 15 would be for skiing and towing...17 for a little less acceleration and a bit more speed or 19-21 for higher speeds and less acceleration(good for fishing to get to where you need to go faster). They also have a wizard to calculate what size of prop you should use according to the weight of your boat and equipment and how fast you want it to go eg. skiing,general use and fishing. It told me that if I switched from my 13 1/8x15 to 12 5/8x21 that I could hit 51mph with my 85hp Force. Check it out http://piranha.com/enginelist.php?ma...23&submit.y=12

  10. #10
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    I forgot to add this...15 would not be the best route to take right now since you have no tachometer and you can't tell what rpm you're maxing out at. A 15 pitch might put you higher than your reccomended rpm range with that size of boat. Id go with the 17 until you get some type of tiny tach or a in dash tach installed.

  11. #11
    Lieutenant Junior Grade pecheux's Avatar
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    Wink Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    A tachometer is like having a motor doctor on board.
    a bad day fishing is better than a good day at work ..

  12. #12
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    I have a 1989 force 85HP and still have the owners manual. It says that you will get best performance with a 13.5 x 15. I just bought new one and it has worked out well for me. I am able to get to 39mph but probably higher now since i got all of the problems on my boat fixed. I am sure i am over 40mph now.

  13. #13
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    Default Re: 1987 Force 85 HP - Which Prop to use 15, 17 or 19 pitch?

    Give this a look: http://greatlakesskipper.com/product...ter-gauge.html This is right setup for our force's.
    "That's what a ship is, you know. It's not just a keel, a hull and sails, that's what a ship needs. That's not what a ship is. What a ship really is.... is freedom."

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