Sunday, 26 February 2012

Fun with a pressure washer

There are those that say you should never use a pressure washer on a boat. It can damage the paint, tear off mastic around fittings, and cause leaks. I say if the paint is so easily damaged, and the mastic not tough enough to withstand such treatment, blast it off!

The one downside of keeping my boat at Old Mill Creek is that in winter, there are about 3 months when the sun never touches the boat. To the south of the boat is a hill covered in trees. The trees form a horizon which very closely follows the path of the sun across the sky. One day, you've got the sun all day. A few days later, the sun is just below the trees, all day. Old Mill Creek enters it's shady season.

During that time, the dew often stays on the boat all day, and work outside is rarely pleasant. Painting and epoxying is hopeless. Best to forget about the outside, and watch the boat turn green.

But now, the sun is back! Hurray. I'm the owner of half an acre of plastic covered in green slime! A day with a pressure washer transforms the boat. Still not pretty, but you can see where there is work to be done.

I'd made the cockpit and the aft platform from panels of foam sandwiched in polyester and glass. The panels were laid onto beams, screwed and epoxied down, and the joins glassed over with tape and epoxy. I'd hoped to be able to paint gel coat onto the joins, and phoned the manufacturers (West) to check whether this might work. I'd found conflicting stories on Google. West advised me that the get coat would stick fine, so long as the epoxy was entirely cured, sanded, degreased and so on. I followed the advice. Here is one of the joins, after the pressure washing:

So even after the most careful attention to detail. the bond between the (textured) gel coat and the epoxy has failed.

I'll paint over such places with epoxy primer when the weather is warm enough.

I'm pleased to note that none of the mastic I used around deck fitting or the windows was damaged at all by the pressure washer.

The pressure washer doesn't send a constant stream of water out of the nozzle - it sends pulses. I noticed that the sound it made on the deck changed occasionally, and realised these were areas that had been damaged and there was some delamination. Some of these places, I could see cracks in the gel coat when I looked closely, and it seems that something hard and heavy was dropped onto the deck in these places. Before I paint the deck, I'll pressure wash it again, and note these places. There were only 3-4, and just small areas, so they won't take long to fix with a grinder and a bit of epoxy, glass and filler.

Next time I consider buying a dirty boat, I might offer to pressure wash it for the owner first. It's been quite revealing.

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