Osmosis - osmose ("Snowman")

10.02.2009

Notre ami anglais Dan, nous amène un autre sujet inédit : l'osmose... Le First 18 a globalement bien été épargné par ce sujet, mais en 30 ans, l'entretien (ou non) a pu faire apparaître cette petite maladie (pas trop grave) du polyester...

"... As for the osmosis; I wasn't really sure what to look for, but after stripping several layers of antifouling and the also some of the old, damaged, gelcoat finish, I noticed a peppering of small erosions.

Within each little concave depression I could see a white, almost powder-like texture. These depressions varying from about 1mm across to 5mm across.

I'm sure if it was a lager boat, kept on a mooring, I'd be very concerned.

As it is, I gave the boat 3 coats of epoxy and was content to "ignore" the problem since the boat lives ashore and is only launched for daysailing. I'm going to add a few more coats of epoxy in the spring since the hull picked up a few scratches on launching anyway.

All in all though, I'm fairly confindent in the integrity of the hull and I have thought about a channel crossing. If the boat was on the south coast, rigged and ready to go and if the weather was favourable I'd probably make a dash across (albeit at a steady 4 or 5 knots!)."

"... I think the osmosis can be attributed to her time on freshwater lakes. She has, as far as I am aware, been kept on moorings on freshwater lakes for most if not all of her life. Lake Windermere and Rutland Water (a reservoir) figure prominently in her history.

As I understand it, boats sailed and moored in freshwater do suffer more with osmosis. I have attached a picture of the hull after removal of anti-fouling and paint.

As you will see there are a number of white patches. There are not that many and they are relatively small, but I believe this is what osmosis looks like. However I haven't had this checked professionally;

she's a small boat that doesn't retain a high value so I'm not overly concerned as to the osmosis now that I've painted several layers of epoxy over the hull below the water line.

I'm getting a lot of enjoyment out of her and she's more than paid for herself, even if the osmosis proves to be a real problem."

Celà mérite discussion ! Est ce arrivé à d'autres ?