505 repair
When the damage has cracked the laminate under the gelcoat, it’s
important to repair it as soon as possible to prevent the onset
of osmosis.
1.
Cut away all the damaged material with a power tool to eliminate
the weak spot. You’ll probably find you need to grind a much
larger area than you initially thought. This also creates a rough
surface to help the new materials bond. Once you’ve got through
to the foam core you’ll need to strengthen the area by replacing
the materials you’ve taken out.
For this use a mix of polyester resin, catalyst and microfibres.
You only need a very small amount of resin with just two per cent
(a couple of drops) of catalyst. Then mix in some microfibres to
give it some bulk. Stir until the mixture has a fairly sticky/runny
consistency. NB The microfibres are not very pleasant to inhale
so make sure you wear your particle mask for this task.
3.
Apply the mix to the wound with the use of a spatula and don’t
be too concerned if the resin is proud of the hull.
3a.
4.
When the resin starts to set (a toffee consistency) use a knife
or chisel to cut off the excess. Carefully cut away the resin just
below the surface of the gelcoat, so that when the new gelcoat is
applied a flush surface will be created.
Once the resin has completely set, mix up the gelcoat
from your gelcoat pigment kit, once again using two per cent catalyst.
This should be an exact colour match (most boat manufactures should
be able to supply you with this information). Mix the gelcoat thoroughly
to ensure all the catalyst is evenly distributed.
6.
Apply the gelcoat to the wound using a brush to eliminate air bubbles.
To avoid spending hours sanding back an uneven surface, tape a
piece of Mylar or slot gasket material over the repair and leave
it to cure. Remember to coat the material with gelcoat before applying
it to the repair.
8.
To speed up the curing process you could use a hairdryer at this
stage.
9.
Once the resin has completely cured, gently remove the Mylar and
you should be left with a smooth surface with only a hairline ridge
around the edge to polish out.
Use wet and dry paper and throughout the job keep the paper lubricated
by dipping in water. Wet and dry paper is graded by particles per
inch. Start of with 320 (320 particles per inch) and gradually increase
the grade (getting finer) throughout the process until you end up
in the final stages with 1,200.
11.
For the final polishing stage you need piece of soft cloth, a rubbing
compound such as T-Cut to polish out the remaining scratches and
plenty of elbow grease!
