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When we dehumidified the hulls we also removed the badly bent anchoring point for the spinnaker pole stays on the port hull. This came back to haunt us, when we turned the hull over to remove it from the shed we heard a piece of metal fall inside the hull. It was clear that the reinforcing plate had fallen off.
At this point there was a lot of cursing of production boat builders and impact of building boats to a budget and not keeping maintainability in mind.
A quick email to Hobie proved that this was not an unusual problem, they have a guide for fixing this, so we weren’t the first. Click here for the guide.
First step was to cut an 80mm hole in the side of the hull with a hole saw (This leaves you with a central piece you can replace), the position is defined in the document. What we found was pretty disappointing, there was almost nothing holding the backing plate in situ.
The shaped recess had been created but no laminate put over the plate and whatever glue had been used had failed probably because there was no oxidation inhibitor for the aluminium. The other noticeable thing was the thread had been cut at too shallow an angle and was cutting through the back wall of the plate. Which at least explained the bent fitting.
Unlike the Hobie suggestion we decided to use structural adhesive to put the backing plate in. SpaBond is a Gurit adhesive which is super strong, the sort of stuff Lotus stick their chassis together with, and has a quick curing time. We glued the aluminium plate in and put a nut on the back of the M6 end fitting.
The Hobie instructions lacked detail on how to ‘close the trap door’ as they describe it. So we spoke to our tame boat builder and foil supremo Nick Harvey. He suggested cutting a plate 10mm wider than the hole we cut into the hull. Then gluing that in place inside the hull and bonding the centre part of the hull left from the hole saw back on to the plate.
This creates a watertight seal, and means we have to use less resin, filler and gel coat to fair the hull in. Once the plate and central piece where bonded in place we sealed the edges with resin, filled the gap where the hole cutter cut into the hull with AWLFair epoxy filler. We didn’t fill the gaps completely, we left a trough between the hull edge and the central piece, this we then bevelled slightly and filled with gel coat.
We then sanded the surface with 280 grit sandpaper to get the surface fair with the existing hull. Then began a series of grinds and refills with gel coat to hide the worst of the repair. Not being boat builders this is a labour intensive pass time and in truth we got to the point that we felt it was ‘good enough’. The boat has been through the wars since it was built and she should carry her scars with pride. As long as the hull is smooth and fair it isn’t going to affect performance.
To that end we followed the same process as for the rest of the hull, 2x 400, 2×800, 2×1200 and 1×1500 wet and dry sandpaper followed by a coat of G3, G10 and finally Harken hull polish.