Osmosis: Don't Worry, Be Happy !

[bludden]

Arco, I would like to know more specifics, what builder and model and are you talking about proper osmosis as I understand it, i.e. delamination of the "structural layers" or gel coat blisters/delamination of the chopped strand mat placed below the gel coat to prevent "print through" of the knitted/uni directional glass...osmosis in the bridgedeck laminations !!!...How could that be ?... Please give us more specific information.

[arco]

If I was to say that had I agreed a sale at an acceptable price which was only to fall through because of the problems postulated, what then?

[Nicholson58]

Spot on GEMINDAWN,
We have a 1984 Camper & Nicholson 58 ketch. It was seriously damaged in hurricane IVAN while at the PO's dock & for sale. Big price reduction and now its in Muskegon Michigan. We worked four years towards restoration. One season was devoted totally to putting on a new bottom. We scraped the layers of bottom paint and then had it sandblasted. This exposed many hundreds of thousands of gel blisters up to about 6 mm diameter. These we ground out with a high speed carbide burr and filled with WEST epoxy. These were non-structural of course but they were all portals into the matrix. I noticed that most of these seemed to have at least one dry glass fiber that may have provided the water path. Some even had antifouling blue wicdked in that penetrated the matrix as well. At least, this indicated poor wet-out. We also angled with the changing daylight over the hull and found seven bulges extending over larger area. I drilled into these and relieved several cc's of nasty fluid under pressure. WEAR A FACE SHIELD! These we cut/ground out and faired back at about a 15 degree angle. They were 6 to 12 mm deep. The finished repair diameter was determined by finding the point at which no more 'water/acid' oozed from the matrix. This left patches up to about 1/2 meter. These we fillled with West Epoxy and glass. I faired the bottom using a large right angle buffer with flex pad and 40 grit. Next, we applied 6 coats of Interprotect 2000E and 3 coats of Vivid anti-fouling.

It was a horrible project but, as you pointed out, solid GRP below water and massive hull thickness with even more massive interior structure reduces my worry. The boat is balsa core above water but solid 25 to 30mm thick below with two layers of kevlar burried in the matrix. The rudder was a total loss. See my photos.