Critique this ob mounting

Discussion in 'Outboards' started by fallguy, Sep 17, 2020.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    thanks..I mounted one engine in the fourth hole and the other in the second...debating on moving the lower one up two holes..

    If I start up as high as I dare think it'll work, I'll have 5" of movement downward only. If I start as low as possible, I might be dragging things even when I jack all the way. The jackplate has a high low position as well, so I can also bolt in two places in position two. BAnd, of course, the engine mounting holes. I am aiming for cav plate to be close to the transom bottom or just under.

    port engine jack is down all the way here

    A37EAC44-18F8-45ED-BB42-813ED2EF66D3.jpeg
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Do you have any guidance from the plans about where the cav plate height needs to be ?
     
  3. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    No. I have not bothered RW about it. He is in the middle of a move.
     
  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I just thought there may have been a drawing that showed an outboard mounted, and you might get an idea from that.
     
  5. brendan gardam
    Joined: Feb 2020
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    Location: east gippsland australia

    brendan gardam Senior Member

    The boat is looking good. I could not even take a guess at engine height with so much rocker.
    It looks way too much for a power boat but Richard knows what he is doing so it's not for me to judge.
     
  6. kenfyoozed
    Joined: Mar 2005
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    kenfyoozed Junior Member

    I know you asked for apples and oranges, but I wanted mention my experience, which may be seen as bananas. On my pontoon the engine was set per the specs and formulas. I figured it was ok. But when we beached the boat i could not raise the engine enough to get the prop higher than the bottom of the hull. We needed to get the prop higher than the hull so we could float in very shallow areas along the beach/ barrier islands to get to shore. So I added a hydraulic jack plate. While testing it, running at WOT and starting with it in the lowest position and slowing raising it at a certain point the boat lurched forward and instantly picked up 5mph. When this happened it startled me. The engine was higher than the original position and about 6" higher than what the specs or formulas require. From now on every boat i own will have a hydraulic jack plate. This way I can dial it in for the load the boat receives on any given day. The formula gets you in the ball park but being able to dial in the height on the fly with the jack plate is awesome. So if you are worried i would suggest a hydraulic backplate system. I love mine. Plus now I can get the entire engine out of the water. Perfect for when the kids are swimming at anchor around the boat.
     
  7. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    except this is not a planing vessel, so a manual jackplate should be fine; we are only looking at 25mph top speed

    we can tilt the engines all the way up
     
    kenfyoozed likes this.

  8. kenfyoozed
    Joined: Mar 2005
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    kenfyoozed Junior Member

    if efficiency isn't a worry then mount them where you want them, it doesn't matter. They look good to me. Love the vmax. I have a 250...wonderful motors
     
    fallguy likes this.
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