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92 Mako 17 Pulls to Starboard

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  • 92 Mako 17 Pulls to Starboard

    92 Mako 17 with a Mercury 90 hp Optimax. Runs at about 5200 rpm wide open. It has a push-pull steering rod.

    I bought the boat 3 years ago and it has been like this since I bought it. The motor pulls hard to starboard. I have the motor skeg adjusted as far as I can to steer the boat to port but it doesn't make much of a difference. I am constantly fighting the wheel to go straight and if I let go, the boat will turn sharp to starboard. The wheel turns easily in both directions when not under power. I grease all fittings every season.

    Could this be torque (prop walk)? Any thoughts?

  • #2
    Merc are know to be torquey. What prop are you turning, 3 or 4 blade and what pitch?We had Merc 19 pitch, 4 blade pushed with 125 Merc on our 17 without steering torque issue. One solution would be to install NTB steering or another might be prop swapping. Others have had issues with hull twist if I recall.
    Keyman[br]Paoli, PA

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    • #3
      Do you notice a difference when you trim up the engine? I get a lot or prop torque on the wheel when trimmed down all the way and it goes away as I trim the engine up...
      Chris Miller[br]Mystic Islands, NJ[br]1974 17 Classic[br]1988 211 Classic (sold)[br]1990 Grady White 230 Gulfstream (sold)[br][img][br]

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      • #4
        Thanks for the replies guys.

        It is a 3 bladed 13.25 x 17P prop (#77344A45 17R)

        I tried trimming the engine up today while running wide open. There was maybe a slight decrease, but not significant. I gradually trimmed it up until it started porpoising and didn't get any major difference.

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        • #5
          Do you have cable steering? Do you fell the pull in the steering wheel?

          What side is the engine trim tab adjusted to?
          2007 Everglades 243 250 Suzuki[br]1988 201 Yamaha 200 - Sold[br]1990 261 T/200 SWS - Sold[br]1978 25 225 Johnson - Sold[br]1975 20 85 Merc - Sold[br]Jacksonville, FL[br]

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          • #6
            I would try the trim tab in the other direction. It always seemed backward to me when I adjusted mine.

            I'm thinking the leading edge of the tab should be pointing toward the port side.
            1984 Mako 228 w/ 175hp E-Tec [br]1983 SeaRay 26\' Sundancer w/ 454 Big Block spinning Volvo DuoProps (Sold)[br]1989 Wahoo 17\' CC w/ 88hp Evinrude (vacationing in Key West)[br]

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            • #7
              My thoughts exactly. The adjustment of the trim tab is counter intuitive at first. If the boat tends to steer left, turn the tab in the direction that you would think makes the boat go left. The reasoning is that the tab does not create thrust in the direction it points but rather it adds drag thus reducing the tendency to turn in that direction.

              Start with a setting a bit (maybe 15 degrees) off of center and test. The setting you end up with works optimally at a specific speed only so test at the speed you usually cruise at.

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              • #8
                Well, I took the above advice and it seems to have improved it significantly.

                The boat was pulling hard starboard and I previously had the trim tab rotated as much as could be rotated so the leading edge was to Starboard and the trailing edge was to Port.

                I adjusted it as far as possible in the opposite direction today so that the leading edge was to Port and the trailing edge was to starboard and the pull is much better. There is still some tendency to pull to starboard, and I can't adjust the trim tab any farther, but it is nothing like what it was previously.

                I wish I understood the physics better. I assumed the tab worked like a rudder, but it seems to work opposite.

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                • #9
                  The lower unit is of course "steering" the boat, not the trim tab. The trim tab is just helping it go that way.
                  1984 Mako 228 w/ 175hp E-Tec [br]1983 SeaRay 26\' Sundancer w/ 454 Big Block spinning Volvo DuoProps (Sold)[br]1989 Wahoo 17\' CC w/ 88hp Evinrude (vacationing in Key West)[br]

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                  • #10
                    You should also post a pic of what hole you have the motor in. Too much drag on lower unit as mentioned above will make it pull one way or other. Might need to move the motor up a hole or two.
                    Steve[br]Wayne PA[br]1971 Mako 17 with a 2001 Merc 125 (sold...missing here already)[br]1989 Mako 250 with twin 2001 yamaha hpdi 200s

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                    • #11
                      It's not a mounting hole issue. As I mentioned the adjustment of the trim tab fin is counter intuitive. Also small changes n make a lot of difference. Once set at an optimum angle for a given speed, just changing the tilt of the motor can have an effect on the tabs performance.

                      If you look under the cavitation plate at the bottom of the tab you may see tick marks. If so, use them as a reference and start with an angle of 1 1/2 ticks and take a ride.

                      Let's also make sure that the problem is not that the boat tends to steer on it's own but rather is harder to turn in one direction that the other. That is related to trim tab angle. The tendency for the boat to steer on its own ( the wheel rotates when you let go) is normal for steering that has feedback. The desirable steering box is one with No Feedback. With NFB steering the wheel stays wherever it was when you let go of it. It still may be harder to turn in one direction but that is again a trim tab adjustment issue.

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