Osmosis treatment and UV damage

[CharmCityBoater]

I have a Tayana 37 built in 1985. I am doing a gelcoat peel down to bare fiberglass. I planned to let it sit through the winter and then sand, fair and barrier coat in the spring. As most boats, it’s made of polyester resin. Should I protect it with tarps or will the polyester resin be ok exposed through the winter months as it dries out.

Thoughts?

[Nicholson58]

Where will the boat be? Mostly, I’d say leave it open unless you are in a rain forest. S Florida, don’t worry.

[CharmCityBoater]

Baltimore Maryland

[coopec43]

Fiberglass used in the 1980s is not UV resistant so it would be better to leave the gelcoat on over winter. (But it would be OK anyway)

Do you have to take the gelcoat off now?

[CharmCityBoater]

Yes, already removed. I can cover with tarps but I keep getting conflicting details. Some say no issue, others say cover. Seems to be no consensus...

If I could continue fiberglass work with epoxy in the fall and winter I would. Just too cold.

Anyone else have feedback?

[Scrimshaw4]

Given the low humidity during the colder months in the Baltimore area uncovered should help dry the hull. I would recommend periodically checking the hull with a moisture meter. If the readings go up or if it's anotherr rainy winter you can always add a tarp. Will you be fairing the hull prior to applying the barrier coat? Sherwin Williams makes an excellent 2 part vinyl barrier coat. I had it applied 11 years ago and my hull is still dry. JMHO

[guyrj33]

I would tent the boat to keep rain off of the peeled surfaces.
If possible i'd slide the whole boat inside a temporary shelter. Is there any concern with dirt building up in the exposed glass and causing adhesion problems?

[CharmCityBoater]

The rain is not the issue. Occasional rain and snow will not impact the drying process. My main concern is UV damage. I know epoxy and UV do not mix, however, my boat is laid up with polyester resin and glass, not epoxy. Should I be concerned about UV and polyester resin?

Also, not concerned about any dirt. It will be sanded very well prior to me doing the work in the spring.

Thanks

Phil

[bradfordharley]

We peeled out boat last year. Rain is good for it and ideally you would periodically rinse it with fresh water as it dries out. I guess it depends on how much UV you get. We were in a high IV environment and there was no apparent degradation when I inspected, sanded etc. Are you going to peel the entire mat later? If not, mat isn’t particularly structural and I wouldn’t worry about it. Your boat is also very overbuilt.....

[Clivevon]

Hi. I'm no expert but have had my boat treated for osmosis twice - once in Mallorca & once in UK. More deeply than just a gelcoat peel. First repair lasted 10 to 12 years - 6 years in for the 2nd time. Fingers crossed. Both times the boat was left exposed for around 18 months - I guess only the UK experience is relevant to you though. I assume you have detected blisters on the hull. Based on what was done with my boat I would suggest you do the following:
Leave her open to the air - maybe just tape a drip skirt just above waterline level;
Mark off the hull in sections minimum say 2 ft x 1 ft (pencil lines) & number each section.
Buy a decent moisture meter (Tramex Skipper Plus is good - USD$468 on Amazon US) & take regular readings on each section & keep a record. Maybe write the readings & dates on the hull section also? You want to get down to a reading of maximum 5.
Get a steam cleaner & regularly use it to give the hull a good steam pressure wash to clean off any salts emerging from the hull as she dries - if left they will block the pores in the hull & stop the drying process.

I like this surveyor in UK - Nigel Clegg. You may find his website useful - it includes sensible notes on osmosis, its treatment & guidance on how to use a moisture meter
https://www.passionforpaint.co.uk/si...article&id=151

According to him a boat will not dry until all glycols are washed out, & once that happens it will dry in 2 to 3 weeks. My own tortuous experience would certainly bear that out.

Good luck. There is always a solution.

[Clivevon]

PS: peeling didnt work for me. Later grit blasting (twice) & multiple Hot Vaccing was needed to do the job. Moisture readings would not budge then dropped like a stone after 2nd grit blast - but the problem was deep seated as the first treatment had significant faults only later revealed. Anyway - we got it done in the end.

[CNulli]

I don't think UV will be a problem. You should get a pressure washer with hot water and pressure wash the bare hull once or twice a week. This will help break up the crystals and let the moisture out. You might consider hot vac depending on how wet the hull is. Just finished my hull after one year on the hard. I ended up doing my own hot vac system to speed the process.