Transom mod.

Discussion in 'Powerboats' started by Nasher, May 17, 2015.

  1. Nasher
    Joined: Apr 2005
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 33
    Location: Pompey, UK

    Nasher Junior Member

    Hello all.

    When I built my boat up from a neglected hull a few years ago I found a really good deal on an XL shaft Suzuki DT200EFI. The transom had already been cut down for a long shaft which put the engine very low in the water, so I looked at ways of raising the transom to suit the XL engine.

    Rather than rebuild the transom in wood and fibreglass I added a 15mm thick Aluminium plate bolted to the transom and filled the original cutout in the transom with a piece of 4 x 2 Ali box section, mainly to fill the gap visually.

    The two images below show the drawing I made beforehand and what it ended up like.

    I'm going to whip the engine off for some tidying up in a few weeks, and for various reasons I am considering putting it back together without the 4 x 2 box section, so the top engine bolts will just be through the 15mm Ali plate.

    Am I making a mistake? I don't think it will have any effect on the strength of the installation but will simplify it.
    I'd be interested to hear what any of you who are far more experienced than me think.



    Attached Files:

  2. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    What are the "various reasons" ? Is getting the spacers to stay put while you install the bolts a problem ? If so, you could cut an access hole with a hole-saw through the inboard side of the box section, and the 6mm plate, don't use the spacers, and have the bolts take up against the other wall of the box section, that sits against the thick plate. But what you have now seems well executed.
  3. Nasher
    Joined: Apr 2005
    Posts: 14
    Likes: 1, Points: 0, Legacy Rep: 33
    Location: Pompey, UK

    Nasher Junior Member

    Thanks for taking the time to reply.

    The spacers are located easily as one end passes through a hole slightly larger than their diameter in the outer side of the box section, and finishes flush with the outside edge. So the box is clamped in position by the inner edge but is purely a spacer to make the transom look the same thickness all the way up.

    My reasons for removing the box and spacers are as follows:

    The installation is over complicated to meet the need, and at the time I did it I put form over function.
    I'd rather a simple installation.

    The bolts are longer than they need to be and pass through a 'sandwich' of 5 different bits of metal including the engine saddle. Shorter bolts and less layers means stronger bolts and less points at which movement could occur.

    I never did add the capping, believing it was tidy enough, but in reality the box filler isn't the same thickness as the transom by a small amount so the inner plate bends out at the edges slightly creating a small gap which I've tidied up with the same white sealant used on all the edges.
    I see it every time I look at it but others probably don't.

    I can not be sure what's going on inside the box section, after 8 years it could be full of sea or rain water and somehow leaking down into the transom, although the last bit is unlikely as I bedded the box down into sealant.
    A simple installation would allow me to see what's going on better with no hidden voids.

    Oh and lastly, I'm a tinkerer, and can't leave things alone.

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