Something like oakum

Discussion in 'Materials' started by fallguy, Oct 12, 2019 at 10:34 AM.

  1. fallguy
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    fallguy Senior Member

    I have a space I need to temporary seal. There is nothing behind it. I was wondering if I ought to pack it with something like ropes.. no idea how/what..
     
  2. Blueknarr
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    Blueknarr Senior Member

    Pictures are worth thousands of words.
    How big a space?
    Surrounding surface profile?
    How strong?
     
  3. jehardiman
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    jehardiman Senior Member

    You would be surprised how much pressure well adhered good quality duct tape will hold.
     
  4. fallguy
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    fallguy Senior Member

    It is a beam socket. Just needs to be sealed and removable sealant.

    35B49B6A-AD9C-4C7B-9FC7-790740849675.jpeg
     

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  5. Blueknarr
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    Blueknarr Senior Member

    You mean the 3/16 gap between the aluminum extrusions?

    How frequently does it need to be opened up then re-sealed?
    How much flex does the seal have to endure?

    My off the cuff recumendation;
    Self adhesive foam weather stripping from the hardware store applied to the incert 1/4 inch below surface. Top off with favorite flexible nautical sealant from a caulking tube.
     
  6. jehardiman
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    jehardiman Senior Member

    Soft wood wedges with a splash cover is how mast partners have been sealed for centuries. Supports as well as keeping water out. Modern materials are rubber and sealants.
     
  7. fallguy
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    fallguy Senior Member

    Between fiberglass and the extrusion.

    anytime the boat is disassembled for hauling..this is a 15' beam opening with an aluminum mast

    it is a through hole in the boat, but saltwater would cause crevice corrosion if it gets inside the mast
     
  8. rxcomposite
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    rxcomposite Senior Member

    A good quality marine grade sealant will do. Adhesive sealants like Sika works well for long term but difficult to remove as it adheres to the base material.
     
  9. Barry
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    Barry Senior Member

    It appears that there is an aluminum extrusion that is fibre glassed into the plywood. Is this correct?
    If so---------
    It appears that you have created a well which any water coming down the mast will accumulate producing a corrosion environment and you are trying to
    seal the well 100% against any water ingress.

    So if there is the outside aluminum extrusion, I would remove the one that is in place and substitute it for one that would sit into the well and say 6 inches taller
    up the mast. Fibreglass the outside extrusion in place and fill the well slightly proud of the surrounding fibre glassed plywood,

    Your mast would then sit only into the 6 inch protrusion of the outside extrusion to prevent a water retainment area as before. Around the outside extrusion,
    drill several small holes to permit any water that comes down the mast to weep away.

    When you insert the mast, you could use an alternative "compression pump packing" or "rope style packing material" that are available for other applications.
    Google both topics above.
    I suspect that these may provide some permeability in the presence of water so after the "rope" is installed, ( I suspect that you need to provide stability
    for the mast loads) you could then seal only the upper joint above the rope so that its removal would be easier, say a 1/2 inch bead of a Sikaflex product

    As a further barrier to corrosion if then the Sika seal fails would be to paint the outside of the mast and the inside of the mast receptacle
     
  10. fallguy
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    fallguy Senior Member

    nonono

    sorry Barry, this is a powercat

    that is a horizontal beam socket

    my bad; should have been clearer

    see the hole by the paper lists? That hole is in each hull...

    E4825093-60B8-4507-986D-E2FDE447526D.jpeg
     

  11. Blueknarr
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    Blueknarr Senior Member

    I hope I don't have to retract this suggestion when more information arrives.

    It looks like there is raw exposed foam against the aluminum sleeve. If so, the skins could delaminate when the aluminum presses on them.

    I would;
    Enlarge the cut out
    Replace some foam with thixo
    Tie the skins together with a couple of layers of cloth
    While creating a chamber around the out side.

    Seal everything up with silicone. It can be cut away fairly easily.

    The chamfer should be larger than on my drawing. 15710245780551153749212.jpg
     
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