Hull repair.

Discussion in 'Fiberglass and Composite Boat Building' started by Frosty, Aug 21, 2012.

  1. Frosty

    Frosty Previous Member

    How would you go about repairing a 1.1/2 inch hole in a fibreglass hull where a sea cock had been moved. The glass is approx1/2inch thick.

    The inside of the hull is barely accessible since fitting out with a wardrobe which is why im changing the location.
     
  2. tunnels

    tunnels Previous Member

    Can you get to the insdie at all ??
    With that thickness of hull is best done 50%inside and 50% outside and feather the hole at least 60 to 80 mm all round with a grinder both sides Yes sound like over kill the size but its also peace of mind !!
    Last thing you need is to hit something and have it pop off inside the hull or fall off outside the hull specially if its below water level !! :eek:
    could be done between tides if you do the outside first and anti foul it then do the inside !:p:D:p
     
  3. Frosty

    Frosty Previous Member

    Can you get to the inside ---Kind of --with my finger tips I could open and close the cock.

    Im beginning to mis my steel boat!
     
  4. Landlubber
    Joined: Jun 2007
    Posts: 2,640
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    Location: Brisbane

    Landlubber Senior Member

    Yeah Tunnels is about right, simple job to do and with a bit of care the inside will not need grinding anyhow when finished.
    Glass has to be ground off at least twice the hole size. Remove the gelcoat before reglassing as resin will not stick to the gelcoat.
     
  5. Frosty

    Frosty Previous Member

    Obviously then your meaning a polyester resin glassing repair and not epoxy.

    How would you support the 1.5 inch of glass over the hole?

    Bit of masking tape on the inside?

    I might be able to feather off the inside and then get say 6 layers of progressively bigger pieces of glass in my hand and pour resin on it then in one big goop reach in and bog it and smooth it out with my hand. Something similar on the outside.
     
  6. tunnels

    tunnels Previous Member

    Just wet out the layers of glass on a piece of ply or stiff card board and pick it up and place in the hole and just dab it down with a brush dont try to push it all the way through!!
    I prosume your boat is polyester ??? or is it epoxy ?? do you know ??
    If its epoxy use some fast hardener and warm it up before you start !!.

    A one minte search and found this !! figure 8 is what i would be doing if its all possibe http://www.westsystem.com/ss/repairing-machined-holes-in-fiberglass/
     
  7. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Masking tape works well.

    If you can only get to the outside then use epoxy, it will bond very well and you won't need to do anything to the inside.

    Although with a 1/2" inch of glass you could do it from the outside even with polyester and not have any problems. You need to make the repair a little larger (taper out from the hole further) so you get enough surface to bond to though.
     
  8. Frosty

    Frosty Previous Member

    Its Polyester!! certainly not epoxy.

    Yeah something like that, I would not push it through just smooth out the edges so I did'nt have to grind again. Then on the outside I could grind a lovely smooth hole blending in with the inside job.

    Grinding is going to be a prob --its inside a wardrobe and the missus goes ballistic if she gets itchy.

    Note to self --make plenty cheese sandwiches for a weeks supply---at least.
     
  9. tunnels

    tunnels Previous Member

    On an ocean sailing boat dont guess !! repair inside and out side so the new glass touchs and really bonds well never do repairs from just one side !!never !!
    You want to be a one way sailer !! :confused:
     
  10. Frosty

    Frosty Previous Member


    Boy--that would be easier if your sure that would work.
     
  11. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    It's nice to do it from both sides, but it's not always possible. With epoxy it will be fine, using polyester you need to do a better job, but it will still work.
     
  12. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    I would make a GRP plug, 1/2" thick, slightly larger than the hole on a plastic sheet so it won't stick to the table. I would ask my wife to place it on the hole through the wardrobe, then mark the circumference with a pencil from the outside.
    With an angle grinder, trim the patch to fit the hole, leaving a collar 1/8" thick. Use some polyester, epoxy or whatever you have, place it over the hole from the inside and keep it there with wedges until cured. Then trim the outside so it is a bit tapered, cover it with a few layers of glass and sand that later to make it look good.
     
  13. Frosty

    Frosty Previous Member

    Seems like there is more ways to skin a cat.
     
  14. hoytedow
    Joined: Sep 2009
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    Location: Control Group

    hoytedow Carbon Based Life Form

    Empty the wardrobe. Remove the wardrobe and give yourself room to do a proper job. Cover all her clothes and everything else in the cabin with a plastic sheet before grinding. Vacuum after grinding and before glassing. Keep her happy and yourselves from drowning.
     

  15. Frosty

    Frosty Previous Member

    Removing the wardrobe would mean an expensive re fit, of course the clothes will be removed but deep down under the wardrobe is the fuel tank. I have about 6 inches from the tank to the hull,-- which Is why im shifting it.
     
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