35SC contender with 300 Yamaha engine mounting height

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  • 35SC contender with 300 Yamaha engine mounting height

    any links to correct mounting height of engines in general

  • #2
    At your typical cruise RPM, with the motor trimmed up only to the point of best efficiency, and no further, the anti-ventilation plate should be at the surface of the water.

    But with most things boating related, what works for the goose won't work for the gander. There are simply too many variables for a one size fits all approach. Most will raise the motor until something adverse happens. Then go back down one hole.

    With my boat and the engine height that I preferred, the propeller would ventilate in a sharp turn. I just knew to trim down a bit going into the turn and then trim back up coming out of the turn.



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    • #3
      Start by talking to Mister Contender. He'll know. Alt, talk to Prop Gods.
      But if you insist on doing it the hard way, here's my Dimes worth:

      CAVEAT: My experience is all with non-stepped hulls.

      1 Run a straight-edge along the bottom of the hull at the point of the engine centreline, that's the first 'baseline' measure.

      2 With the engine trimmed to a vertical position, as it would be when running at a comfortable attitude, for every 1 foot aft of the transom (the transom not any bracket or moulded "euro transom" that the nose of the gearcase is, go up 1" above this straight-edge position. Theoretically, that's where the centre of the anti-cavitation (anti-ventilation) plate should intersect the baseline (plus the above increases).

      3 Test run and observe the water over the anti-cav plate as described in the previous post. Most commonly you'll go above this theoretical starting point by one or two holes, so expect this starting point to be the lowest you're likely to be.

      NOTE: The lighter the boat, and the higher rake the prop is will result in even higher positions.

      Example One: My 1800lb, 21 ft Haines Ski boat with a "full length" hull, ie no bracket etc, runs a Verado 300 Pro with Enertia 23" prop at 4 holes above the above 'straight-edge' plus set-back "theoretical" line

      Example Two: My 9500lb, 31 ft Jupiter CC, with the Armstrong Bracket, runs dual Verado 300's with 20" Revolution4s is at one hole above the 'straight-edge' plus set-back "theoretical" line.

      Hope this helps!
      Jupiter 31FS / Verado 300s in Fiji - V8's on order
      Haines 2100SO / Verado 300 Pro in NZ

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      • #4
        Originally posted by [email protected] View Post
        any links to correct mounting height of engines in general
        This the older side console model?

        Here are instructions for bracketed or non bracketed boats.
        Click image for larger version

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        Engine Sales and Service
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        954.463.4904
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        • #5
          I have a Robalo R180 with a Yamaha F150. With a Merc Rev 4 I get maybe 5300 rpm. Another boater says he gets 5700 rpm or better. He says he has his motor all the way up. I have mine on the 3rd hole down. Or, I could go up 2 holes. Will raising the motor really get me 400 rpm??????? Does raising the motor get any rpm????

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          • #6
            Originally posted by Kingrex View Post
            I have a Robalo R180 with a Yamaha F150. With a Merc Rev 4 I get maybe 5300 rpm. Another boater says he gets 5700 rpm or better. He says he has his motor all the way up. I have mine on the 3rd hole down. Or, I could go up 2 holes. Will raising the motor really get me 400 rpm??????? Does raising the motor get any rpm????
            Will it get 400 if raised two holes? Mostly likely, just need to be careful of aeration. Raising it certainly will get RPM.

            Engine Sales and Service
            Ph +1 954.463.1515
            Fx +1
            954.463.4904
            Toll Free: 800.622.6747

            [email protected]
            www.parkeryacht.com

            Member of the MSHS Group

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            • #7
              Definitely ask what kind of load the other guy has on the boat when he's getting those RPM and speeds.
              as for if you'll gain the RPM, its possible.
              "IF" you gain speed from the reduced drag, "THEN" you will also gain RPM.
              I've seen boats gain 5 MPH by raising the motor 1 hole, that said, I've seen guys try every different mounting hole and the boat runs the same regardless. some are more touchy on height then others.

              Ken Reeves
              [email protected]
              941-735-5808

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