Prop number - Help me pick a prop for my son's boat motor!

Discussion in 'Bubba's Outboards' started by Hookman, Apr 11, 2006.

  1. Hookman

    Hookman New Member

    Messages:
    56
    State:
    dELYRIAs ohio
    my son has a 17.5 ft tri hull boat, with a 80 hp. merk it is set up too pull a skier. the prop is a merk # 15p serial #4877342a4 . the boat will only go 28 mph. what # prop would make the boat go 40 to 45 mph.....HOOKMAN?.....
     
  2. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    People worry too much about speed when the most important gauge on your boat is the tach.

    If that merc is taching near or just below 5500 rpm's then changing the prop will only damage that engine.

    It being set up to pull a skier out of the water, I would think it probably is propped low and could use a higher pitched prop.

    I hate to ask what the max rpm's are now, but if they're well into the 6000+ rpm range than a 17 would probably be about right.

    Without a tach, there's no sure way of knowing, damn the speedometer.
     

  3. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    That water flow meter that they call a speedometer has killed many a good engine.:)
     
  4. Hookman

    Hookman New Member

    Messages:
    56
    State:
    dELYRIAs ohio
    the boat was clocked by a G.P.S. the boat hits full speed in 60 to 75 feet. im thinking waist of gas!!!!!!.....hookman....
     
  5. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Yup, waste of gas for sure, now what about the "tachometer"
     
  6. Hookman

    Hookman New Member

    Messages:
    56
    State:
    dELYRIAs ohio
    the moter was reving 6s. i think....hookman.....
     
  7. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    Get the 17 pitch on there before disaster strikes.

    Don't expect 40 to 45 mph though. A tri-hull is not known for speed. It does give you more stability when anchored and a softer ride. If you can get that speed, great.

    I know a guy that put a 9.8 on a 14' jon boat and got 21 mph out of it, but he's a bit crazy.:p
     
  8. jim

    jim New Member

    Messages:
    2,579
    State:
    Jacksonville NC
    Go to the Mercury website and click on their prop selector section.It will ask you details of the boat and based on those details you supply will make a prop recomendation.It even asks if you want top speed ,pulling power etc.Realistically off the top of my old gray head I doubt you are going to go 45.High 30s might be more realistic.:)
     
  9. SeedTick

    SeedTick New Member

    Messages:
    1,414
    State:
    Conway Arkansas
    Didn't we see some pictures of that? If so I agree with the bit crazy part. HEHEHE

    ST
     
  10. squirtspop

    squirtspop New Member

    Messages:
    968
    State:
    Glencoe, Arkansas
    Hey Seedtick, I noticed you are out and about already this year. I got loaded this morning with em....seedticks that is. LOL
     
  11. FishMan

    FishMan New Member

    Messages:
    2,293
    State:
    Tennessee
    the 17 quick, at least it will be close and you will know better what to do.
     
  12. Hookman

    Hookman New Member

    Messages:
    56
    State:
    dELYRIAs ohio
    thank you all for the great imformation. any one know how much a #17 prop will coast?....hookman....
     
  13. Bobpaul

    Bobpaul New Member

    Messages:
    3,039
    State:
    Supply NC
    From a couple hundred for an aluminum, to several hundred for a stainless.
     
  14. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    Even at that cost its better then toasting that engine. Turning 6 gs with that engine its headed for disaster in short order.