Sealing standpipe in dorade boxes

Discussion in 'Fiberglass and Composite Boat Building' started by chowdan, Dec 20, 2019.

  1. chowdan
    Joined: Jul 2008
    Posts: 102
    Likes: 3, Points: 18, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    Currently aboard SV Osprey, we have 4 dorade boxes, 1 on port, 1 on starboard, 1 split between head and passage between saloon and vbirth and one split above the doorway leading to the aft cabin and main saloon.

    I love them, they add great amount of ventilation on the boat but the current problem is - the standpipes leak. The forward one has a plastic tarp over it to prevent water coming in now that its rainy season, and the port/starboard ones haven’t had an issue until last night.

    As winter is directly a head of us, fiberglass/epoxy work is out of the question until next year so I am doing some research as to what would be the right way to fix the issue.

    The current design is that the dorade box is a giant fiberglass box with a lexan plate over top with the cowls screwed in. The standpipe is a piece of 4inch PVC pipe bedded through the deck with what looks like either 4200 or something similar.

    I’ve thought about maybe just pulling the PVC, cleaning the box out and doing any sort of epoxy repairs needed then re-bedding the standpipes back in place with 4200 or similar compound. Should last a good 4-10 years before failing, but then I thought about how its a PITA to deal with every 4 years or so. That being said my current idea(open to suggestions) would be to either encapsulate the entire PVC tube in some fiberglass cloth. This would then make the joint between deck and standpipe essentially water proof and as such I’d not have any issue with water leaking through that joint.

    Granted that would be far more work that pulling the standpipes and just regrooping them back in place, but I’d rather it be done once, done right and not have to worry about it for another 30 years

    Anyone have any suggestions or opinions?
  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    First, how far does the standpipe extend into the box? And then, what do the drain ports look like. If water is standing in the box, that could be your trouble.
  3. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    A good temporary fix to get you through the winter might be to goop up suspect areas liberally with wax.
    Toilet bowl wax rings are a cheap source for this, and can be easily removed in the spring.
    Don’t forget to clean up real good with acetone before applying any epoxy.
  4. chowdan
    Joined: Jul 2008
    Posts: 102
    Likes: 3, Points: 18, Legacy Rep: 10
    Location: Seattle WA

    chowdan 1980 PAC41 Liveaboard

    I agree that I need to double check that sizing of drains are correct but regardless it doesnt solve the fact that the leaks are occurring due to the sealant surrounding the PVC standpipe has failed

    Thanks! That's a great tip! I use toilet bowl wax for the hole surrounding my mast. Never thought about using it for temporary leaks!

  5. fallguy
    Joined: Dec 2016
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    Location: usa

    fallguy Senior Member

    Try butyl tape for a temp seal. Roll it in between your hands to about 1/2" round and press it in. Bedding in butyl is good all around and if it leaks; you can usually find the root cause on a look.

    When ready, replace the tops and faces with Lexan and light up the cabin.
    bajansailor likes this.
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