Gelcoat stripping?

[drewpster]

I need some real world advise on whether I should tackle barrier coating my hull below the waterline. I was hoping I can find someone locally to strip the gelcoat for me and do the recoating myself. I need to make a decision on this soon so I can get some drying time before warmer weather. I know just enough about the subject to get myself into real trouble so I need some advise.

 

[ondarvr]

Re: Gelcoat stripping?

Why do you want to strip the gel coat off?

 

[drewpster]

Re: Gelcoat stripping?

Osmotic blister problem. Stripping the gelcoat exposes the laminate so that it can dry. Then a epoxy barrier coat is applied then paint. No more blisters.

 

[ondarvr]

Re: Gelcoat stripping?

I just wanted to know if there was a good reason to remove it.
It's very time consuming to remove the gel coat and layers of laminate with blisters in them, so be ready to spend a great deal of time under the boat if you try that part of it. Once you've spent all the time and money to do it, they can still come back, so don't be surprised. Typically it's not the gel coat that blisters, although that's where you see them, it's the resin in the laminate that fails. You do need to remove the gel coat to help it dry out and get to the blistered laminate, but your hull is still made from resin that will blister, so if the epoxy barrier coat lets any water through (and it will), it may blister again. Blister repair can be done succesfully, but it's not easy or quick.

Some shops will offer a warranty on the reapairs, but not if you do part of the work, so if it fails you don't have anybody but to stand behind it.

How bad are the blisters, do they really need to be repaired and how big is the boat?

 

[flashback]

Re: Gelcoat stripping?

Blisters, the cancer of the boat world.. mostly, its all in the layup. If there is a void in the laminate, water will find a way.. it mixes with the resin, creates pressure and pops out thru the gel like a blister..if you have isolated patches of blisters less than the size of a dime, you can grind them out and just do a local repair in that area. If most of the hull is covered in blisters then you can remove all the gel with a grinder or a peeler.. tent the boat, put a de-humidifier in the tent, and let it set for a year.. washing the hull down with soap and water once a week because the hull will scab over as it drys and you need to remove that scab so it can dry further.... then your about half way thru the job. check it frequently with a moisture meter and get it as dry as you can...Then it is time to re-build and fair the hull... lots of epoxy resin and fillers and lots of sanding and fairing.........and like cancer in humans, there's no sure thing...
If your boat is not totally eaten up, then I would suggest using a die grinder with a burr in it and grind each blister out and fill the void with epoxy filler, give the boat a good bottom paint and prepare to do the same thing again in a couple of years.. but there will be less to fill the next time ...................

 

[drewpster]

Re: Gelcoat stripping?

The boat is 24 foot. The blisters are not localized to one area but they do not cover the entire bottom either. The largest is about the diameter of a golf ball. I had not planned to do any blister repair. This boat is very old (1969) we just wanted to improve the looks of it and maybe get a few more years use. I had the boat at a yard last year doing some transmission work. The yard owner put me in contact with a company that does boat bottoms locally. I was advised by them that given the age and size of the boat a complete blister repair would be cost prohibitive with no return on the investment.
Of course I agreed at the time. I don't think that the problem is a danger to the hull. There are no large soft spots. The boat has been on stands since last April while I am doing some painting and improvements. Time is no great issue as we have a new baby in the house and I do not anticipate putting the boat back in the water for awhile.
I know that peeling the hull will be expensive. Not to mention the cost of barrier coating fairing and painting. I guess I need to weigh the benefits versus the cost. I have been told the problem is largely cosmetic but can become a problem if left unattended. The restorer in me says I am doing the job half way if I do not repair the blisters while at the same time I think it may be going too far given the age of the boat. I never intended a complete restoration but the more I improve the worse the unimproved portions of the boat look. (I anticipated that) I just refinished the deck end of summer this year. It was a big job in its own right including sanding, fairing and painting the entire surface. (with repairs and changes) I started sanding and filling the cockpit area before cold weather set in so I have been working on some electrical changes I wanted to make waiting for warmer temps.
Maybe I can scratch this itch by grinding out the worst of them and letting them dry a couple of months. And then fill them when spring is sprung. What do you think?

 

[drewpster]

Re: Gelcoat stripping?

Here is a link to some pics of the boat in progress if you want to take a gander.

http://s136.photobucket.com/albums/q187/drewpster/?start=20

 

[ondarvr]

Re: Gelcoat stripping?

Since the hull aready has blisters, which means there is water in it, the only way to stop or slow down the blistering is to do a complete strip, dry and recoat with a product designed for that purpose ($$$) and that fix may not last. Blisters are not normally a structural problem, but repairing the larger ones would be a good idea. Even without repairs it would most likely last many more years and only the fish will know you improved the looks.

 

[flashback]

Re: Gelcoat stripping?

yep, golf ball size is pretty big... that usually means the water is deeper in the laminate.. you will need to grind out an area somewhat larger to get to the wet part... and then glass in the divot once the laminate is dry.. If you do each blister individually, the smaller ones can just be filled with epoxy filler and you have the surrounding area to fair to.. the bad thing is you will probably not get all of them so you will need to do it again in a few years.. but like I said before, hopefully there won't be as many.. I have a 78 Oday sailboat that I have been working on for 20 years, last time I took it out I only had 20 or 30 small blisters to deal with... it,s just the way it is with older glass boats, but wood and metal require periodic maintainance also.. good luck

 

[flabum]

Re: Gelcoat stripping?

http://www.daviscoltd.com/nams/Documents/Blister_Report.html



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