Replacing a through hull shaft strut

Discussion in 'Fiberglass and Composite Boat Building' started by motorbike, Jun 9, 2021.

  1. motorbike
    Joined: Mar 2011
    Posts: 163
    Likes: 10, Points: 18, Legacy Rep: 87
    Location: Beam Reach

    motorbike Senior Member

    Unfortunately I managed to break the bronze P strut off at the hull, possibly 40 years of electric mice nibbling away, now I need to replace it.

    I will be replacing like with like, the question I have is about the bonding method. The boat is solid polyester and the strut is inserted vertically through a slot into the boat like a blade. Once its at the right height and angle with the shaft etc lined up two holes are marked and drilled into which two transverse bronze pins are inserted in such a fashion that the part is supported against the hull. Then its lightly bonded in place, and after the glue has set then the whole top is covered in cloth and laminated in place.

    The question I have is this, can I simply use polyester resin with glue fibres as the bonding agent and polyyester with chopped strand as the laminate? All the boatyard chatter is to use epoxy but my take is that previous polyester method has lasted 40 years, didnt fail and although I know it has lesser adhesion to itself than epoxy to poly, its still seems a reasonable to use it. The main motivation is to use "like with like" and the speed of cure so I can launch quickly the next day (there is huge yard pressure at the moment). I am very familiar with epoxy work and have no bias either way, its just a matter of expediency.

    Thanks for your advice
     
  2. bajansailor
    Joined: Oct 2007
    Posts: 2,202
    Likes: 745, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Is the boat currently hauled out, or is she still in the water, waiting for a slot in the busy yard?
    Have you managed to source a new P bracket, and is it all ready to fit in the boat now?

    If the boat is hauled out now, could you post a photo for reference of the break?
    And a photo (or two) of the boat itself would be nice as well.
     
    Last edited: Jun 9, 2021
  3. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    Some biaxial fabric recommend for the lamination, CSM is just filler, has very little structural value.
    Vinylester resin might be a good compromise, it handles much like polyester, and bonds to it, but is stronger and has better water resistance.
     
    bajansailor likes this.

  4. motorbike
    Joined: Mar 2011
    Posts: 163
    Likes: 10, Points: 18, Legacy Rep: 87
    Location: Beam Reach

    motorbike Senior Member

    Thanks for your help, I built it in carbon
     
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