Wheezing but happy

(first published May 2005)

Yesterday I dodged the showers and prepared the inside of the hull for repair and painting. (If all this is familiar to you then skip the next four paragraphs.)

Explanation - when a small GRP dinghy is popped out of its mould the outside shows the same high standard of finish as you see on any yacht or motor cruiser; but the inside is as rough as a badger’s bum. A yacht has a set of GRP internal mouldings which means that you see the same smooth shiny gelcoat finish inside and out, but a dinghy like Lugg - because it’s small, relatively cheap, and has to be kept light - has no internal mouldings. The inside of the hull is just the rippled surface of the Polyester resin over the rough chopped strand mat. This is usually painted so that it feels OK to the touch, but no real attempt is made to achieve a smooth finish - it would take too long and cost too much.

So Lugg’s insides were rough - not just because of the production process, but because he’s been repaired a number of times over the years in various places on the hull, and each time it added to the irregularity of the inside surface. First I sanded as much of the existing paint as practicable, with a power sander where possible, but also by hand; then I levelled the bigger irregularities in the surfaces with Polyester filler and sanded that to a reasonable finish. Finally I had to repair the joint between the centre-board case and the hull as I mentioned in a previous article.

Having cut glassfibre chopped strand mat to suitable sizes, I mixed some polyester resin and painted the surfaces to be repaired with it fairly generously. (You have to work quite fast once you’ve mixed the resin because it hardens in about 20 minutes.) Then I laid the shaped mat into the wet resin and stippled more resin into the surface until it was completely saturated. I worked around both sides of the plate case with an initial layer which was local to the damage, then laid another layer over the whole area of the join on each side. I worked about two inches up the plate case and about six inches on the horizontal hull surface. This picture shows the mat and resin laid up in the hull - it’s a reddish colour, although the light wasn’t good for the photo.



Finally I skimmed the whole lot with a thin coat of filler to make the repair look like the rest of the hull and sanded it smooth. This photo shows the grey filler being sanded and a bracing strut in place to hold the plate case vertical while the resin hardened (it was leaning slightly to the starboard side).



You can see the sanded surface of the (grey) original paint in these shots. Tomorrow - all being well - it’ll change to dark red when I put the new paint on.

Using polyester resin is always dodgy - the fumes can make you ill - so I did the lay-up in the open air. I still ended up wheezing. Mind you, when I was teaching in Sussex a colleague and I made a GRP kayak in a workshop in one week after school hours. It was winter and cold, so we kept the windows closed. I was laid up with styrene poisoning from the fumes for about a week afterwards. I won’t do that again!