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Bubbling on Gelcoat

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  • 11-02-2015 12:53am
    #1
    connel42
    Registered Users Posts: 175 ✭✭


    Hi

    Looking for advice.
    I am restoring a 1962 Van De Stadt Randmeer 21ft sailing boat.
    The hull is sound apart from some bubbling above the waterline near the bow.
    The bubbles are not very pronounced but more obvious when the sun shines on the hull
    The gel coat itself seems in very good order and it still very strong and will not move when pressed hard.
    I dug one out with a chisel and there seems to be no delamination.
    It is very puzzling to me as they do not appear to be blisters.
    I don't think it is osmosis.
    My suggestion is to sand them down fair with the rest of the hull as I will be panting the hull navy anyway.
    Any advice appreciated.
    The photos are not great but may be of some use.


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  • Options
    #2
    fergal.b
    Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,320 Mod ✭✭✭✭fergal.b


    They could be osmosis caused by pin holing, sand them out with 60 grit paper or disc back a few mills bigger than the blister and a bit deeper than the gelcoat then give it a good wipe with alcohol and use a gelcoat repair kit leaving it a little bit proud, when set use paper on a block to bring it back smooth.



    .


  • Options
    #3
    Glenalla
    Registered Users Posts: 432 ✭✭Glenalla


    connel42 wrote: »
    Hi

    Looking for advice.
    I am restoring a 1962 Van De Stadt Randmeer 21ft sailing boat.
    The hull is sound apart from some bubbling above the waterline near the bow.
    The bubbles are not very pronounced but more obvious when the sun shines on the hull
    The gel coat itself seems in very good order and it still very strong and will not move when pressed hard.
    I dug one out with a chisel and there seems to be no delamination.
    It is very puzzling to me as they do not appear to be blisters.
    I don't think it is osmosis.
    My suggestion is to sand them down fair with the rest of the hull as I will be panting the hull navy anyway.
    Any advice appreciated.
    The photos are not great but may be of some use.

    Looks very much like osmosis. Open one up and wipe the area with your finger, if there is a smell of vinegar from your finger then it is osmosis. There does not have to be delamination of the fibreglass if the bubbling is between the gelcoat and the skin coat which it normally is.
    If it has a vinegary small open the blister entirely and wash regularly with fresh water and the allow to dry, this will dissolve all the acetic acid which is the build up causing the blister. Once sufficiently dry, probably a few months you can fill with a good waterproof filler, preferably epoxy, and repaint.


  • Options
    #4
    connel42
    Registered Users Posts: 175 ✭✭connel42


    Thanks for that
    I did dig out one and looked do any moisture but it's dry and also any sharp smell but none there
    I think the best course of action is as you suggest - fully expose each blister and wash thoroughly
    Thanks

    Next i need to tackle the grp deck but that question is for another post

    Connel


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