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  1. #1
    Cadet
    Join Date
    Jul 2005
    Posts
    21

    Default What pitch prop do I need for my 25hp Yamaha

    I have a 2008 25hp Yamaha pushing a 14' fiberglass trihull what is is best pitch prop for max preformance? I just bought a 13 pitch SS Solas New Saturn and it ran poorly decreasing speed and hole shot.

  2. #2
    Supreme Mariner
    Join Date
    Apr 2002
    Posts
    16,757

    Default Re: What pitch prop do I need for my 25hp Yamaha

    2 stroke or 4 stroke?Is boat full dress or basic bare boat?
    Without performance specs of original prop(prop size ,max rpm and speed)
    prop selection is a crap shoot at best.which unfortunately you confirmed.
    What was original prop it should be marked.

  3. #3
    Cadet
    Join Date
    Jul 2005
    Posts
    21

    Default Re: What pitch prop do I need for my 25hp Yamaha

    Its a 2 stroke the origional prop was a 11 1/4 pitch. The spec sheet said the rpm range was 5000 to 6000 the 14' x 5' boat is just a rear bench seat tiller handle operated, with a front swivel seat mounted on a post. (not that heavy of a rig).

  4. #4
    Supreme Mariner
    Join Date
    Apr 2002
    Posts
    16,757

    Default Re: What pitch prop do I need for my 25hp Yamaha

    I should have asked before;what are you trying to do?
    Wouldn't hurt to at least know your speed.Maybe you could borrow a GPS.How did it perform with the 11 1/4 prop.
    Going from aluminum to stainless will usually reduce rpm.but can push better.Increasing pitch reduces rpm and power can go faster if the motor can spin it yours can't..So you did a double whammy.
    First you should put the 11 1/4 back on and at least get your speed. Check the motor height.Starting point the antivent plate should be even with the bottom of the boat.Raise the motor about 1/4" at a time till just before venting becomes a problem.Use 1/4" sticks to support.just be sure it pumps water and the clamps have a good grip.Under ideal conditions an inch can gain 2 to 3 mph.Also carefully adjust trim as each stick is added.Improving speed can also improve mileage,may help handling and hole shot.
    To get back to the "crap shoot".Without your max rpm and speed We don't know if the motor is within its proper rpm range.operating outside the range
    can lead to premature motor failure and inefficient operation.
    You may be able to borrow a shop tach or buy a Tiny Tach,reasonable price and easy install can be used on any similar motor without regard to stator poles.
    I would say the factory would figure that motor to be pushing boats very similar to yours And I'll bet if there is a standard prop it is the 11 1/4.
    If I was going to crap shoot a prop it would be an 11 1/4 stainless.
    Keep in mind the best trim(not height) for speed is not the best for hole shot.
    Under ideal conditions your motor should be in the 28-30 mph range.
    Factory speed specs are based on a light fast boat ideally setup.

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