Plastic is basically durable and long lasting. But some types are still vulnerable to age and sunlight. Our boat from year 2000 has Lewmar low profile hatches, with thin plastic frames/fairings on the inside. The frames are taken out occasionally when I need to lower the saloon roof sheets. I have some solar panel cables and oher stuff in that area, and thus the frames are unscrewed and lowered when I need to check on it. This handling of the frames is destructive as they become old and brittle.
The orange area is old fiberglass reinforcement of the frame rim. The green area is where repair of the rest of the frame has started.
With som pieces of wood and some clamps, the sides are straightened and reinforced with fiberglass. The corners are done afterwards. I sanded the plastic to ensure that the resin will stick.
2 sides done on one frame.
Some pieces had broken off from the frame.
Above picture shows the start of the repair of the screw area. On the underside a piece of very thin glass fiber mat (30 g/m2, buildup is unwanted because of flushness to the roof) was saturated with resin. It was so thin that I should have used two mats to avoid small holes. The blue-ish stuff is resin thickened with microballoons and filled in from the other side.
I was lucky to have some small scrap 2mm fiberglass sheets from another project. These pieces were made to reinforce the destroyed screw hole areas. Small glass fiber sheets can also fairly easily be made with a couple of glass plates or something similar.
A mixture of resin/microballons was again used to fill and glue the pieces in place.
The frames were treated with plastic primer and painted with an oil based silk finish paint. I think they came out OK. Only disadvantage I can see is that a bug screen might drop 2mm lower from the frame and thus theoretically could create a crack for small bugs entry. It remains to be checked. Countermeasures would be taken :).
After a while I decided to try to fix a frame that was in reality even worse off. It had been repaired with polyurethane glue, but that glue is rather flexible and does not stiffen the frame much. In addition mould has a tendency of forming on it, and it does not work well as a filler of cracks. The polyurethane had to be removed. A glue remover (Tec-7 Remove All) was used. It is quite strong, and did in some spots dissolve the plastic slightly. So the answer to this is to have a bit of patience and not use too much glue remover at a time.
Removing old polyurethane glue. Not really a fun job. But most boatowners would not have put this on in the first place.
There was an old reinforcement of the rim in this frame too.
This time I chose to make a rough mould out of epoxy tooling doug. One single screw attachment point on the frame was in good shape, so I could pack the epoxy tooling doug in some plastic cling film and press it down from the underside to make this mould.
The mould is here attached with clamps, plastic cling film is used to prevent resin to adhere to the mould.
Once again resin with micro balloons was used, carefully distributed with a sharp vooden stick and good glasses....
Resin was also put into the large cracks. For the small cracks, some softer car repair putty can do. It is best to avoid sanding of the frame, as it has a special surface structure that would be affected. Most of the putty was wiped off with alcohol and a rag before it dried. The screwpoint areas did not have to be especially smooth and nice, as a reinforcement would be resin glued on top.
Reinforcement pieces in place as with the previous frames. In addition small sheets of glass fiber mats were put on the underside also here, as well as under cracked areas. Finally the sides were straightened and beefed up a bit, also as with the other frames.
I think the result is acceptable, and hope the repair will last.
Good job! This is also still coming to me. My Lewmar frames look partly also no better. I have the feeling that the frames are not UV stable in the long run and become brittle. Also, they are quite expensive, for such a bit of plastic.
SvarSlettMaybe in a not too far future, someone can make a code for programming such plastic pieces in 3D printers.
SvarSlett