GRP damage and water absorption

[skyflyer]

For the first time e er I kept my boat afloat this winter in one of the winter berthing packages offered by various marinas.

Mistake! (Albeit my own fault)

Long story made short, the bottom of the transom (below waterline so unseen until we hauled out last week) has sustained scuff damage, removing an area of gel coat about 12cm x 1cm and exposing the GRP layup beneath.

this has therefore sat underwater for about two months by my best estimate.

The exposed area doesn’t seem spongy or soggy.
what are my best option? If water has been absorbed into the matting how far might it have traveled.. can I accelerate drying if needed? The boat is due back in the water mid April.

the main layup used vinylester not polyester, which I gather was to reduce osmosis problems. Does this mean it would be water resistant?

many thanks.

 

[dankilb]

AFAIK gelcoat does very little to protect vinylester resin layup from moisture, in the grand scheme of things.

I may be wrong, but by guess would be that osmosis-style moisture ingress ought not to be a concern.

You will, however, still need to dry the area out before repair - which could take a couple of weeks from lift out IMO.

 

[Stemar]

According to articles I read when researching the problem of "osmosis", moisture does next to no damage to properly laid up GRP, and I suspect it takes a good while to form blisters if there are voids and loose styrene.

By all means do the repair, but I'd give very serious thought to whether I wanted to lose a few weeks out of my sailing season, or whether I'd just go sailing and worry about the repair while out of the water for next winter.

 

[skyflyer]

According to articles I read when researching the problem of "osmosis", moisture does next to no damage to properly laid up GRP, and I suspect it takes a good while to form blisters if there are voids and loose styrene.

By all means do the repair, but I'd give very serious thought to whether I wanted to lose a few weeks out of my sailing season, or whether I'd just go sailing and worry about the repair while out of the water for next winter.

My thoughts too, to be honest; dry out as well as I can, reapply a "temporary" gelcoat and then sort it next winter when I have time. My understanding was that vinylester gives much better protection than polyester (which is why the manufacturer used it for the below waterline part of the hull) . Also because it is at the transom/hull junction it is a really thick, solid layup.

 

[waynes world]

If it was mine i would just repair it once dried out as much as possible, then fill with West System epoxy and 407 filler.

Water can soak through the matting by capillary but take s along time and would not worry about it.