Re-installing motor on boat

NickhoogNickhoog Posts: 774 Officer
I removed my motor for a new gelcoat job and will need to put it back on. Now questions have entered my mind.

1) Is there a torque spec for the mounting bolts?

2)Placement: I know that the cav plate should be equal to the "bottom" of the hull, but what if there is a "step" between the actual bottom and the end if the boat; i.e. hull runs back, stops and then there is a 3" step up to the actual transom. In this "step" there is the drain plug, livewell intakes and drains (area with 3 bigs holes in pic). Question is where exactly should the engine be placed???


Thanks in advanced.


  • aboveboredabovebored Posts: 1,239 Officer
    Coat stainless bolt w 5200 and use heavy washers and stainless lock nuts. Hand tighten real snug. You want cavitation plate egual with lowest point of hull.
  • FS DanFS Dan Posts: 2,347 Moderator
    Assuming that the boat was set up correctly for all the years used until the re-gel, the boat hole used on the motor should be fairly evident by wear marks on the engine bracket. If the engine is new, run a straight edge from the keel and for every 12 inches of set back from the trailing edge(step), you can raise the engine 1". between each hole is 3/4" approximately.

    There isn't a set torque for the engine bolts, I like to snug them up and go another 1/4 turn.

    Formerly Catmandew
  • surfmansurfman WC FLPosts: 5,049 Admiral
    I would mount it higher than it was by one bolt hole and run it like that first, if it doesn't vent then you are golden. You want the motor mounted as high as you can without it ventilating. It will run more efficient and you will get a tiny bit more clearance. When a motor is mounted farther back as with a jack plate it usually can be mounted an inch or 2 higher than the bottom of the boat due to the water rising off the transom as it moves under the boat.

    At the very lease I would not mount is any lower than the bottom of the main hull. Like FSD said above.
    Tight Lines, Steve
    My posts are my opinion only.
  • Alex from GAAlex from GA Posts: 1,240 Officer
    Boat setup, for maximum performance, is mostly trial and error. Props have a lot to do with engine height along with cavitation. Agreed you want the engine to be as high as possible as long as there is enough water pressure.
  • surfmansurfman WC FLPosts: 5,049 Admiral
    If you raise the motor higher than it was originally mounted, assuming it was mounted lower than it needed to be, you may need to up the pitch on your prop too, rpms will go up, not a bad thing, just re-prop.
    Tight Lines, Steve
    My posts are my opinion only.
  • screamin seamanscreamin seaman Posts: 1,492 Officer
  • surfmansurfman WC FLPosts: 5,049 Admiral
    Tight Lines, Steve
    My posts are my opinion only.
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