Osprey 24 Fisherman Pilothouse IO to Outboard conversion

Discussion in 'Boat Design' started by Busanga, May 29, 2022.

  1. Busanga
    Joined: May 2022
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    Location: Ghana

    Busanga New Member

    Hi all i live in Ghana and there are no fiberglass shops here so have to do all the work myself.

    I will have a lot of questions and hope the guys on here can spare the time to help me out with advice.

    I have taken the VP engine out and now need to plug the IO hole .

    i will build Knee braces to anchor the transom more rigidly to the stringers.

    Alot of these Ospreys have been converted and the transoms are apparently strong enough.

    So first question is which is best way to plug the IO hole. Transom is not rotten.

    if someone could give me a step by step , would be appreciated.
  2. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    As with any patch, the bond/bearing surface can be increased by tapering the edges of the hole and patch piece, and complexity can be reduced by enlarging the hole to a rectangular or round configuration that’s easier to work with.
    If there are still concerns about the transom’s strength, you can increase its thickness from the inside, by adding plywood/laminate, then add the knees over that.
    fallguy likes this.
  3. bajansailor
    Joined: Oct 2007
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    Location: Barbados

    bajansailor Marine Surveyor

    Welcome to the Forum Busanga.

    Re how there are no fibreglass shops nearby, are you still able to buy fibreglass materials relatively easily?
    If so, I presume that you can get basic chopped strand mat (CSM) and woven roving (WR) and polyester resin - or are you planning on using (eg) stitched mats if available?
    KapnD has given good advice above.

    For general reference for other readers, here is a link to a few Osprey 24's for sale, so you can see what they look like -
    Osprey 24 Fisherman Boats for sale https://www.smartmarineguide.com/boats-for-sale/osprey-24-fisherman

    I hope that I am not jumping ahead too fast in asking for more details of your proposed conversion?
    Will you be fitting a single outboard engine, or twins?
    How much power?
    Will the engine(s) be mounted on the transom, or on a bracket bolted to the transom?
  4. Busanga
    Joined: May 2022
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    Location: Ghana

    Busanga New Member

    Will be a PDR bracket (can see conversion here) scroll tru wil see my exact boat will poast some pics later of conversions showing knee brace etc.
    PDR Marine » Transom Brackets http://www.pooderbuilt.com/brackets/transom-brackets/

    NOTE the last pic with the 9.9 is the Osprey24 same as mine

    i will be fitting a Verado 300 V8

    my issue is that these pics all show completed conversions i want to know how to do the work.

    i had looked at tapering the plug or even stepping the plug . That is cutting a bigger hole from inside not all way thru so plug would butt up against the inside of the outside skin so to speak and then put a plywood laminate over inside with knees attached to that. then glass outside to flush with a 12 to 1 ratio bevel in the outer skin to accept overlaying glass (do this both inside and out before laying the lamnate board and knees of course), then fair with epoxy. that plug could then not pop out or pop in due to board / knees on inside and 'shelf' on outside. or just bevel 45 deg from inside to out so it cant push out and board up inside as usual with knees ?, ..

    what i would like to know is the schedule that one would use, what epoxy to bond edge of plug to hole, how to lay the mat and due to it being a thick transom i would have to laminate a plug , which is best way to do that ?

    thanks for all help and welcoming me to the site.

    i can get some materials here, but very basic mat and weave and resin etc. (not sure yet exactly which is available at moment, need to check due to covid mess up of supplies) but i can import glass if need be, is not heavy.
  5. Busanga
    Joined: May 2022
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    Location: Ghana

    Busanga New Member

    Osprey with Verado300 V8.jpg 20170221_133902.jpg 20170221_153233.jpg 20170223_120826.jpg 20170223_125555.jpg 20170223_145031.jpg 20170422_101525_resized.jpg

    This is same as my boat and the engine i will put on. This is someone else plug and knees done on an Osprey
  6. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    I would rest the knees directly atop the stringers, laminate over both sides over stringers, possibly extending down to reinforce the stringer/hull interface too.
    This is probably more important than the intricacies of the plug design, it looks like the bracket mounts will fall well outside of that anyway.
  7. Busanga
    Joined: May 2022
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    Location: Ghana

    Busanga New Member

    cannot access both sides of the stringers if you look at the installed pic closely. that is why they are fixed to sides, and i assume bolted through to stringers as well as glassed.

    guys i am completely new to this glassing (have researched alot, , i am a mechanical engineer so am practical ,but have no experience glassing) i really want to know basic procedure to do step by step.

    ie when fixing the board with knees to transom, do i glass board first and sand flat and then epoxy to the sanded transom etc etc...i mean really basic stuff like that.

    actually the mechanical/structural stuff i can figure out, is the actual practicality of glassing the surfaces together to acheive a good bond i need help with
  8. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    I still think glassing one side down and over the stringer will be stronger than the sheer strength of a handful of screws and some putty.
    Laminate becomes a continuous structural piece, transferring load, so the transom piece is glassed to the transom, the knees are glassed onto that, and onto the stringers, marrying the whole thing together.
    The glass in the pictures looks light, I’d be looking for several layers of glassmat especially in the corners.
    I’d prefer to see the plywood transom plate glassed to the transom, glued and screwed too.
    Those flat surfaces outside the stringers serve what purpose?
    I’d be inclined to cut them back a bit in order to bond the knees to the stringers both sides, and you’ll likely find that they don’t have glass on the bottom of them anyway, a great spot for rot to begin.
  9. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    The actual cutout and the new insert won't be taking much of the load, so don't stress over that part failing.

    Making sure the areas where the bracket is thru-bolted to the transom are strong, plus tying the transom into the stringers and hull are what's important.

    You Tube is full of conversions to outboards. You don't need to get info on your exact boat, it's a rather generic process.

  10. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    First, fix the io hole.

    Get us some pictures.

    Determine tbe existing structure.

    probably 2x 3/4" ply?

    remove an excess width of 3" of one of the layers, whichever is more practical, inside or out, use oscillation tool, chisels

    make a new plywood piece to fit it, but cannot be tight, you want 2-3mm gap

    precoat the wood with epoxy

    make a peanut butter or jist less than peanut butter mix using fumed silica and bed in goo and screw it in lightly, back out the screws at 6 hours to 8 hours

    then same on other side

    enough for now, ask questions
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