Stripping Gelcoat

[zoombats]

I wonder if anyone has an opinion, or first hand knowledge of stripping gel coat using a Gel Plane or any other similar device. What have been the quotes/costs for the work if undertaken by a yard? what have been the costs if undertaken by the owner? I am in negotiation for a 46 foot boat and the survey has indicated significant osmosis. The price will be effected by the potential costs. I have received estimates ranging from $15,000/45,000. I realize that figures can vary from DIY remaining on the hard for three months to dry out from the higher cost of the yard applied "hot vac" approach to drying out. Each process involves buildup of new epoxy/fiber laminate, barrier coat and anti foul. Some first hand ideas would be appreciated. Thanks

[Artif]

You shouldn't need to build up the laminate, once the gel is removed, to dry the hull tent it out and install infra red lamps and a dehumidifier until dry enough, and coat with epoxy and anti-foul.
The worst part of the job is removing the gel. A planer set at the correct depth (just remove the gel) with vacuum extract and a lot of blades, a quick run over with a sander and your ready to go. Not a pleasant job and I would pay someone else to do it.
Sorry no idea on costs, but the yard I used to work for did this treatment on a regular basis.

[Mark Johnson]

I have done a number of the old conventional blister repairs, but...

Back in '04 I spent a year + of 70 hour / week in a yard in Pensacola, doing a refit to our boat. In this yard they did these Peel & barrier coat jobs regularly. The total prices were all over the place, but > $10,000 is not unusual!

The extent of the job, and cost, was largely a matter of how thorough a job you / they did, and how thick the hull was from the get go.

The actual "peeling" was done by an outside contractor with vacuum assisted equipment, and wearing a gorilla suit. It was REALLY fast, (like one or two days), and that part of the job alone, (cost wise), might be quite reasonable.

The thing was, the peeling process is quite inconsistent, and removes some of the hull! It will have to be RE-faired, BEFORE the multi step barrier coat process even starts. This is UNLESS a workboat standard is OK with you...

If it is an older hull that is like 7/8" or more thick, then the lost hull thickness is not an issue. If it is a cored hull with a relatively thin outer layer, or a solid hull of only about 3/8" thick, the smart move is to fair AND add a layer of biaxial fabric to the peeled portion of the bottom. This is a LOT of work! Most people didn't re-glass, but on an already thin hull, I would.

Also, after peeling, I would tape a plastic "skirt" from the WL to the ground, all around the hull, and put a dehumidifier under the skirt, for AT LEAST 2 months! Frequent acetone washdowns help too. = more yard time!

When the hull reads "dry" on a moisture meeter, THEN the above process or processes begin.

It might go something like this:

After a few coats of West resin, then a week of microlight fairing, (using a longboard), and more resin, ... (add glass or don't add glass, depending)

Then numerous coats of West barrier coat, sand well, and if the hull is fair enough, and no bare spots, then spray several coats of "Bar Rust" (2 part epoxy used to line fuel tanks), and as soon as it is firm enough, "hot coat" on the first layer of bottom paint. etc.

The work and cost can therefore, vary all over the place! If the hull only had 75 or so blisters, the size of a quarter and just as deep as the gell coat, you can spot grind them out yourself, do the drying and acetone washing process like above to your ground out spots only, then spot repair each one. This shouldn't weaken the hull, and after drying, you can do tha barrier coat process yourself. The above is not as good, but a fraction of the price. You might still have a few more blisters every haul out, but you just repair them each time. This is what people did for years!

Neither scenario is guaranteed to work forever, but if you dry the hull A LOT before coating, and do whatever is necessary to KEEP A DRY BILGE, it will extend your blister free time. (You can segregate the eng and /or shaft bilge, and epoxy line it, and do the same around the base of the mast if necessary. Just TRY to keep a dry bilge. It also lets you know RIGHT AWAY if you have a nascence leak.

Hope this helps, Mark

[Stevens 47]

I had a gelplane, sold it to a member on this forum about 6 months ago. Do not know if he is finished using it yet. The process is pretty simple. It took me 3 days to peel the bottom of my boat...47'. Getting the boat dry is so important. IMHO you may need more than 3 months. Do moisture readings in stages from when hauled to gauge. It will show rapid moisture loss in the first stages and less and less as over a longer duration...but is it truly dry?

Is the blistering truly a structural issue? It is rarely the case that they are. They may affect your resale value...if you get a discount on the purchase price to reflect that possibility you may be OK.

[CharlieCobra]

We're just finishing up a blister boat with over 1000 blisters on a 28' hull. Nightmare? To say the least and blisters kept majically appearing for up to 120 days later. The amount of filling and fairing is staggering for these jobs. I would've peeled this boat knowing what I know now. Is it structural? You tell me if pockets of acid eating at the resin bond within your hull is just a cosmetic thing or not. Some of these blisters would have penetrated to the core had this been a cored hull. I'll never spot grind another one like this again. Our labor and materials alone is over 7K, not to mention any talk of profit of any sort.

[bstreep]

Conversely, our boat was pretty well peppered with blisters when we bought it. At the surveyor's recommendation, we had them individually repaired at bottom paint time, nearly 3 years ago. A couple of hundred of them - a few 3" in diameter. $1000 in additional repair work. We are now looking at repainting the bottom, and this time we have just a handful or 2. I'm not sure that it matters, but we have a hard anti-fouling bottom.

[zoombats]

Thanks all. The blistering isn't really structural (litmus readings were on the neutral scale) but that is inevitable. My main problem is the boat is in a place where it is not conducive to staying on the hard for too long (cost/availability). I think that is why the high end of the repair costs are due to the "hot vac" approach. add to the cost of buildup of epoxy with E glass or some other fiber replacement other than strand mat reflective with the proposed depth of removal to the substrate.