Repair ideas for an inaccesible leak.

Discussion in 'Fiberglass and Composite Boat Building' started by CDK, May 8, 2010.

  1. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 145, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Estimated half a ton of water in two stowage compartments in the aft cabin after a wet winter, caused by a crack in the GRP where hull and deck are flanged together.
    The crack was caused years ago by a ***** crane operator in an Italian marina who almost crushed the boat when he tried to lift it without the proper tool. It was 'repaired' but still leaks.

    There is upholstery on the cabin wall which cannot be removed without destroying it and I cannot order the same material anymore.
    On the outside there is a heavy fender profile running the length of the boat. I know from experience with a much smaller boat that if you pull it off, you never get it in place again because it is too short. The yard probably heats it in a large oven before installing it.

    What are my options?
     
  2. CatBuilder

    CatBuilder Previous Member

    These are very difficult decisions to make, but you will have to destroy something to get in there.

    I would probably take off the fender profile and fit something new in its place, even if the repair isn't perfect, cosmetically. Why? Because fixing a leak from the outside is always the best way to go. Keeps the water completely outside the boat.

    The inside repair (without removing that fender profile) may not keep the water out entirely because it may not go all the way through to the exterior hull surface (you can't know without removing the fender profile).

    So... I'd go at it from the exterior of the boat to ensure you have a complete repair that doesn't allow any water in at all. Is this a cored boat?? If so, time to also break out the moisture meter and see if something cracked other than a hull/deck separation and see if there is water incursion.

    Might a well check for that water incursion before you start the repair because the repair might be a lot bigger of a job if there is water in a core.
     
  3. apex1

    apex1 Guest

    Plastic bags taped into position inside and out. Injection nozzle on the outer bag. Vac on the inner. Vacuum to test the tightness, then inject some (colour matched?), thickened, fast curing EP.
    Leave the bags in position, test after curing, if the inner bag still sucks the outer one. I hope not...........

    Regards
    Richard
     
  4. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 145, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    That would imply removing both the upholstery (furry stuff) and the fender band.....

    I have the camper van packed for a trip to the North. Shopping, visiting friends, my son, grandchildren. Navigator set to avoid highways. Lots of time to brood over solutions.....
     
  5. baeckmo
    Joined: Jun 2009
    Posts: 1,116
    Likes: 116, Points: 63, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    I would certainly go for the fender. You are correct in that it is stretched to fit. We cut the extruded profile ~10% short, heat it in a hot-water tub to something like 70 C before application. With most profiles, you can actually clamp it to the boat somewhere midships for a repair, so that it won't creep away. Then detach the part necessary to apply a repair strategy like Richard suggests.

    That done and the boat tight again, either go for a hot bath of the loose stump again, or even use two or three good hot-air guns plus rope and block for stretching. "Been there, done it all, got the T-shirt"......
     

  6. Herman
    Joined: Oct 2004
    Posts: 1,617
    Likes: 89, Points: 48, Legacy Rep: 1240
    Location: The Netherlands

    Herman Senior Member

    My vote is for the outside as well, if I had to choose. From the outside (after removal of the fender) you can assess the damage.

    I presume that there is a flange on both hull and deck, facing outwards, and a fender is around it, to cover things up and make it nice looking. This fender usually has some screws from beneath to keep it in place.

    I also presume that the bonding paste between the hull and deck has cracked. Usually a polyester bonding paste is used, which is cheap and easy, but does not like point loading.

    If the above is true, then you can cut out the seam with whatever tool you have available (screwdriver, chisel, hacksaw, but I like the "Fein Multimaster" best) and fill the now open seam with epoxy glue paste.

    Should be easy. Unless of course you discover more repair work. I hope not.

    Have a nice trip.
     
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