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| T O P I C R E V I E W |
| Knighty |
Posted - 10 Dec 2012 : 11:41:23
Found two small blisters which were just below the waterline by the outboard. Pretty sure they are osmosis blisters and whilst the boat is overwintering on my drive i would sort them out. Like a prat i am i poked a small screwdriver into one and had an eyeful of the gunky stuff inside, didn't realise they would be under that much pressure  not recommended lucky i had eyewash on my works vehicle handy.
Can someone with more boaty knowledge than me tell me if my repair method is ok ?
Have carefully Dremmiled the gelcoat away from effected spots down to the glass weaving and feathered the edges leaving an area about 15-20mm or so open and washed out those areas and will continue washing out until after Xmas sometime.
Then planning after they are completely dry to apply some epoxy resin then epoxy filler, antifoul primer then antifoul the boat before spring launch. Some web sites say after cleaning them out and drying just antifoul over them to let them breath, just seems strange to leave the glass matting inside exposed to the water.
I know some say just leave them but as it's the only ones i have found on the hull which isn't too bad i suppose for a 33 year old boat and nothing broke/fell off in the misery off a summer we had that wants repairing i would sort them out. |
| 2 L A T E S T R E P L I E S (Newest First) |
| Knighty |
Posted - 13 Dec 2012 : 11:06:02
Cheers Jimbo, not overly worried as it's the only two i can find, underneath the gelcoat it looks sound where the blisters were. Will leave them for a few months to dry out. |
| Jimbo |
Posted - 12 Dec 2012 : 20:19:14
Hi there, Osmosis can and often does appear after many years without becoming obvious. Osmosis occurs when water very slowly permeates though any form of semi-permeable organic coating and will if given the chance slowly retreat to the outside surface and dry out if possible. The problem is that this will only occur with clean water. Should this water encounter any water soluble material it will form a solution which will be unable to pass through to the outer surface and will exert sufficient pressure to delaminate the gel coat or resin coat interface and this is seen as a blister. This is very common in the automotive industry. Given plenty of time the blister can dry out and shrink but will return if there is sufficient water about. The remedial action that you have suggested is correct and should eliminate future problems from this area. |
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