Diamond Pattern Repair

The diamond pattern on the Comet Trio is a distinctive feature of the boat. It adds a suitably textured finish to the areas of the boat which would otherwise be too slippery.

When it’s damaged, it’s possible to repair using fairly simple techniques. It takes a while to plan and do, but each step is fairly simple.

Firstly, we made a mould using silicone moulding materials. We built a reservoir out of plasticine, sprayed the area with silicone mould release spray and allowed it to air dry, then followed the mix instructions, made some up and poured the silicone into the reservoir and left until set. The materials I was using was Polycraft GP-3481-F RTV Silicone Mould Making Rubber 1.1kg Kit (Red Catalyst) and MACSIL release agent, plus plasticine for the reservoir. It took 24 hours to completely set.

 

When this was removed and the plasticine was recovered there was a pattern on the silicone which exactly matched the pattern on the boat. One edge of a suitably sized section was cut exactly along the long dimension of the diamonds, very carefully so that it was possible to visually line the pattern up.

 

The damage was probably caused by towing the boat without properly tying the boom down, so over the period of a journey it’s ground the diamond pattern away on the thwart.

 

The plan was to mend this in two stages – the diamond pattern first, and the flat section second. First, the flat section was masked off, so that any spill from the diamond pattern was allowed to flow over the edge.

 

The silicone had been cut to a manageable size, and coated with release material. The repair area had been wiped down with acetone and allowed to dry.

In order to get the gelcoat into the diamonds, the gelcoat was applied to the silicone pattern and spread to flow into each diamond.

 

Then there was sufficient gelcoat applied to the hole in the thwart. It was not absolutely critical to get this right, as long as there was enough as it could spill over the edge.

 

Now the silicone was lined up with the pattern, which could be checked visually and then felt through the mould and then rolled slowly towards the tape carefully to exclude air bubbles. Then it was weighted down.

 

It was left to set for an hour, and then the silicone mould was carefully peeled off, revealing the pattern.

 

A sharp blade was run along the edge, then the tape peeled away.

Fixing the flat part was relatively simple, it was ground out, filled, sanded and polished.

 

and this is a close-up of the restored pattern.

Thanks to Simon, Giles and Lee for helping out with the maintenance session – Steve.