It would appear I was right to be second-guessing our repair job on the hull as we found some definite weak points when things set up. Upon inspection of the new patches we found a few of them looked like this:
You can see how some of the fiberglass is sticking up a bit from the patch and visible as individual strands. This means that it didn’t bond properly with the rest of the hull. This case is exaggerated because the final patch was a bit big for the hole and extended onto un-prepped gelcoat but we did find a few of the patches had weakly bonded fiberglass around the edges, leaving small air pockets which could be exposed:
Wherever we discovered this we took the grinder to our new patches until we weren’t seeing any more air pockets.
We found these bonding issues only occurred around the outside edges of a few patches and seemed to be caused by a combination of our very heavy fiberglass cloth not fitting perfectly into the holes and not using enough filler to fill the small gaps which remained. This seems to indicate the filler is pretty important in eliminating tiny gaps, at least if you are using heavy cloth as we did.
To repair them we filled with thickened epoxy if it was just a small area on the edge and for the ones which needed a bit more grinding we laid in extra layers of cloth to compensate.
Fortunately, most of the patches came out just fine and only need a bit of sanding and fairing to get them flush with the hull surface:
We’re just about done with the hull patches now but there’s one more monster hole we need to sort out. This one will be a bit of a challenge but fortunately it’s well above the waterline. Then it’s just a bit of fairing and we’ll have a watertight vessel!
This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder