Can a swim deck serve as starting point of a transom bracket?

Discussion in 'Boat Design' started by amSteve, Jan 13, 2017.

  1. amSteve
    Joined: Jan 2017
    Posts: 9
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    Location: wisconsin

    amSteve Junior Member

    Greetings - first posting here and, hat in hand, seek guidance on creating mounts for a pair outboards off the transom of a '71 Gibson - rather than repeat the vitals of the existing boat I could just refer you to the first post of this thread:

    That's the starting point - the conclusion of the thread is (to my mind anyway) is that a pair of Merc 60 big foots will be installed.

    So that's what i have to design for, the motor mounts sufficient to support 60hp engines on a vessel that doesn't aspire to anything beyond hull speed. In fact, the 60hp is 60 instead of 40 just because I choose engines the same way as anchors - I don't want someday to wish i had just a little more.

    Point being that i'm not designing for something that it's not going to be asked to do.

    Now to the point - it has this really solid swim deck - not that I'd think that it could serve as a mounting point - it's jut that I think it's solid enough to be incorporated into the finished product. In essence, my swimdeck is very much like the transom bracket that is overviewed here except not solid - it's 1" alum square bars gapped on 1".

    But a conventional transom bracket is exactly what I don't need because I'm designing for a pair of 60s instead of 250s. So I'd really like to get comfortable with the idea that I can brace up the existing swim deck (from both above and below such that it (the swim deck) brings the same advantages as those transom brackets.

    The Merc 60 weighs 260lbs - the transom is sound - the stern deck has a pair of divot plates that are just begging to serve as the top point of bracing that connects to the outer (back) edge of the swim deck.

    I'm picturing a diagonal brace from stern topside down (about 3' of a decline) to the back edge of the 3' swim deck. I'm picturing adding enough of a lip/ledge (square steel tube?) at the back edge of the swim deck to serve as the mount point. I'm having a really hard time thinking that's not beefy enough.

    As I tap this out i can't help but think it sounds ludicrous to think of using a swim deck as part of a motor mount but then remind myself I have no intention of placing the sort of torque the typical boater expects.

    All in all though - there's probably some math involved that i won't pretend to be aware of.

    Couldn't be happier to hear someone I'm totally nuts and that i should just shuffle of to this or that shelf to buy something proper.

  2. gonzo
    Joined: Aug 2002
    Posts: 16,468
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    Location: Milwaukee, WI

    gonzo Senior Member

    It sounds like something that is possible. You will need to figure out the proper height for the motors to start with though.
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