Blister repairs

KD3PC · Dec 23, 2009

Ken

do your own research...there have been no known cases (according to this and other lists, boat yards, etc) of hull delamination to the point of an unsafe boat...many feel that the peel and strip is but another stop gap, quite expensive I might add. Many surveyors in our area (chesapeake) will simply tell you they are cosmetic...and to repair/remove/epoxy etc.

I am quite sure as Maine says above, many yards do very improper repairs at a significant cost to you, and will have a back out clause if they re appear as they most certainly do...

All the best, and let us know what you end up with as a resolution.

zeehag · Dec 23, 2009

i have had 2 boats with blisters in hull....one was a 26 ft bahama islander----i had the blisters --even the dry ones---filled and the bottom barrier coated----i had estimates for hull tek from the yards---that is the repair where they peel and re glass---for 23000.00 dollars --eeks---i had the fill in and epoxy done for 8600.00 and when the boat was hauled out 4 yrs later, there were still no blisters.
my other boat with hull blisters is an ericson 35. i repair the wet blisters--the ones that develop holes in center and allow the rest to exist and we survive together well with no ill effects. wet ones need to be addressed. these are not structural nor do they develop into structural blisters. i was advised not to worry about dry blisters. they do not slow down the boat or affect the hydrodynamics ....
the pix you have are difficult to see ---looks like the little bubbles in the new stuff is what you are concerned with?? looks like the application of the stuff blistering was the culprit for this---not blisters. good luck....

Ron Roman · Dec 23, 2009

I have the exact situation Maine Sail was talking about. Every fall when my boat is pulled and the bottom is power washed I always have bottom paint (VC-17) blown off in certain areas and I get fish eyes. From a distance they look like blisters. In the spring I'll sand down the areas and touch them up with paint but the fish eyes keep coming back. I'm not sure what my next step is.

Maine Sail · Dec 23, 2009

Ron Roman said:
I have the exact situation Maine Sail was talking about. Every fall when my boat is pulled and the bottom is power washed I always have bottom paint (VC-17) blown off in certain areas and I get fish eyes. From a distance they look like blisters. In the spring I'll sand down the areas and touch them up with paint but the fish eyes keep coming back. I'm not sure what my next step is.

The hull was most likely not properly prepped.

When the gelcoat is blown into the female mold it is blown onto a highly waxed surface. This wax allows the mold to come free of the laminated hull when it is time to pull it from the mold. Unfortunately wax gets transferred to the fresh gelcoat in the process.

Prior to painting it must be de-waxed, sanded then de-waxed again. To be done properly this takes about 100+ rags as once you make a swipe you must turn the rag over so not to re-apply the removed wax. It is a time consuming job to say the least and requires about three to four gallons of De-Waxer for a 30+ foot boat to be done right.

I am so picky about paint adhesion that I would not let my dealer prep my new boat in 2005. It took me about 12 hours to properly prep the bottom to be sure it was 100% wax free.

This dealer does this in about 6 hours and uses half the rags and half the de-waxer. Just for grins I sprayed some water on the boat two over from mine after the dealers yard monkey was done "prepping" the bottom and had gone home.. Guess what? Water beaded like crazy and it sheeted on mine. I guess I made the right decision..

The only real fix is to try and de-wax the areas as they peel or strip the entire bottom and de-wax, sand, de-wax. Always de-wax before sanding a new hull or you will only drive the wax into the sanding swirls and you'll never get it all off. Good paint adhesion will be next to impossible if you sand a new hull before de-waxing it..

Barrier coats should always be hot-coated with bottom paint to form a chemical bond. If you don't it looks like this in no time...

Ed Schenck · Dec 23, 2009

I originally wrote " The first step would be to get the bottom down to spotless gelcoat.". That is why you do that, to make certain they are really fiberglass blisters. The big ones that you can pop and have stinky water in them likely are. But all those little ones will better define themselves when you get all the paint off. The boat shows up at the dealers with a shiny white gelcoat bottom right out of the mold.

Steve Dion · Dec 23, 2009

Ken: While the weather is not conducive to preforming the actual repair, the yard can start on the inspection of the problem so you will know where you are with this problem. I would ask them (and Hunter) to do the inspection and put together a plan. There is no reason the bottom paint cannot be removed so you get down to clear gel coat.

If there are real blisters, then you will need to wait for the actual filling of the blisters. I see no reason not to open up any blisters if they are actually in the gel coat. Then can drain and you will be ready to go once you get some warm weather.

Hermit Scott · Dec 23, 2009

Ken Honeycutt said:
I appreciate all the responses - lot of good information. I'm a little confused about the possibility of the blisters being under paint. Steve and Mainsail - you both mentioned that the blisters could be under paint. Is there actually a coat of paint over the gelcoat? I rolled on a couple of thin coats of VC-17 over the past 2 seasons and it appears that it was VC-17 that was applied by the dealer (not sure of this but it was bluish gray coating when I hauled the first fall). Does the factory apply some type of white paint? When I popped a couple of blisters they were underneath what I assumed was gelcoat since it was white - how thick is the gelcoat? The layer that I popped was about the same thickness as latex paint that I've chipped off a few walls.

Thanks again for the reponses (please excuse my ignorance about gel-coat, that's why I'm asking questions).

Your original post made me feel sick for you about the blisters on a new boat. I hope your blisters are just paint bubbles.

jibes138 · Dec 25, 2009

Chemistry

I'm not a chemist but in the reading I've done on the blister problem is the laminate does not 100% cure and you end up with some of the chemicals mixing with seawater due to the potential difference across the barrier coat. The fix I read about involved cooking the hull at about 170 degrees to complete the cure. In manufacturing FRP products that I've been involved with typically involved elevated temperatures in a mold or an oven.
If the laminate is not cured properly then it really is a manufacturing defect and you might want to ask Hunter to ship the boat back to the factory and make them do the fix where they are properly equipped for it. I'd rather take that route then some bunch of migrant yard workers in a rotten winter environment. The article I read involved putting heat lamps all around the boat to get it up to temperature and holding it there for a few days/hours? Can't remember all the details, I read this years ago so do some research and check on this possibility.
Good luck and you have a lot of supporters, if the manufacturere stiffs you then the publicity will be very bad for them as a lot of people will hear about it.
.

jibes138 · Dec 25, 2009

Info on blisters and the curing temp required (80 degs. C)

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Here's some info on the chemistry problem. Not sure if this applies to the resins used in your boat but it is a pretty logical summary. Not too technical with chemical equations and such but puts it in layman's terms easy to understand. Happy reading. I searched on gelcoat blisters uncured resin to find this.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular][/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.1. "Osmosis" is in reality not an adequate name.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]In the sixties a leading yachting magazine wrote an article about a mysterious "illness" hitting FRP boats. In short it said, that intruding water caused an "osmotic pressure" which de-laminated the FRP layers. The theory was repeated by a lot of other magazines and created the now universally accepted name "osmosis".[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The basis for these articles, most likely, was the results of core sample testing provided at that time. In all samples from blistered hulls, the tests revealed a much higher content of WSM:s (water soluble materials), glycol and free styrene than normal for a sound laminate.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]With the laboratories lacking practical field experience from the problem, an incredibly long-lived but false theory was introduced, that the gel coat blisters are formed when the concentrated solution of WSM:s and glycol in the laminate absorbs water through the gel coat by "osmosis".[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The term „osmosis" was born and spread all around the world![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]In fact there is practically no osmosis involved in the process and it certainly does not create any delaminating pressure.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Today, with the field knowledge that gallons of the substances in question can be found within a few m² laminate, it is easy to understand, that the substances found are created by the process and not the opposite.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Incredibly enough some core sample testing laboratories still report findings of "substances which might cause osmosis damages" and thus keep the myth alive.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Also the myth has been used by the boat industry in order to make the public believe in a "minor" problem caused by a few careless boat builders![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]As late as 1988 a couple of well known boat builders wrote articles in English an Scandinavian yachting magazines, telling that the "osmosis" problem itself was a myth and really did not exist!![/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.2. "Osmosis" reason: Hydrolyse of uncured resin![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Five years of intense laboratory research and practical tests on hundreds of samples from cut up "osmosis" hulls as well as on whole hulls gave us quite a new view of the reasons for and the damages formed by the "osmosis" plague.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The main reason for the "osmosis" was found to be, that boat hulls are too large to be post cured within an economical range.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Post curing at 80ºC after the initial curing in the mould is needed for polyester resins to achieve a total curing of all the polyester chains.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Instead of post curing, usually laminate dimensions are increased to compensate for the 10-15% lower strength due to the missing post curing.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]There have been few considerations about the chemical consequences![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A not post cured laminate contains as much as 10% styrene enclosures with a "skin" of uncured polyester between them and the cured polyester.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Further many of the cured polyester chains have no curing links in the ends, so called "dangling chains"[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.2.1. The styrene enclosures:[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The "osmosis" begins, when under certain circumstances moisture enters into the styrene enclosure. This[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]water in combination with the styrene hydrolyses the surrounding uncured polyester.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The large polyester molecules split into a multitude of smaller acid, alkali and glycol molecules which need more space than the original ones. This creates a pressure which forms blisters in the elastic gel coat.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A not commonly known effect of the "osmosis" process is, that the very small alkali molecules follow the inward capillary movement of the moisture and cause a loss of bond between fibreglass and polyester.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The result is a loss of strength in the hull of 20-30%, and abnormal damage can be caused by the slightest grounding.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.2.2. The "dangling chains":[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The dangling chains are the main reason for many "osmosis" recurrences after common treatments.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]As mentioned before, acid e.g. pthtalic acid is formed during the hydrolysis process. The acid is also absorbed into deeper laminate layers and will stay there despite any kind of normal washing and drying.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]When pthtalic acid molecules come into contact with cured polyester chains attached with "dangling chains", the total chain breaks up into styrene and uncured polyester.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The resulting mixture is extremely sensitive to hydrolysis and needs small amounts of moisture to restart the process.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.2.3. Enough water always available[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Beside from moisture entering from inside condensation and the bilges, even the most successful drying will leave at least 0.5% moisture in the laminate, enough for severe hydrolysis to proceed in spite of high quality watershield systems![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Especially in large hulls with heavy roving layers and/or sandwich core, such a huge amount of polyester can be hydrolysed that several m² of one or more laminate layers are no longer bound together. After a short time this "de-lamination" fills with gallons of an acid/glycol/water mixture.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]If left unattended, in a few years the laminate will have lots of areas where only the gel coat over wet soft fibreglass is left! (See pictures)[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Very often no telltale blisters will form as the pressure is evened out in the de-laminations.[/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.3. Uncured resin in laminate can be hydrolysed.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]To enable an "osmosis" process to start, molecules of uncured polyester, styrene and water must come into direct contact. Fortunately, water cannot affect properly cured polyester.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]However, when moulding FRP, there are a lot of more or less uncontrollable circumstances, which cause excess styrene to be trapped inside the cured material.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Such styrene enclosures are always separated from the cured surrounding by a skin of not cured polyester resin.[/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.4. Why does the "osmosis" not start in all FRP hulls?[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Most "experts" explain that "osmosis" is merely a result of faulty manufacturing. Regarding boats, water is supposed to enter into the hull by diffusion and capillary effects and then by osmotic force be brought into the enclosures.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Not accepting this for a truth, the HYAB organization spent many years analysing "osmosis" hulls for some substance that could be the trigger of the process.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Finally in 1993 the answer was found.[/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.5. Trigger found: fibre strand penetrating enclosure.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Finally in 1993, studying an old laboratory report about "leaching"(very similar to "osmosis") in FRP roofing elements, a plausible theory was found. Even if not practically tested, it gave reasonable answers to earlier pecularities.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The report ascertained that there can be no osmotic force between pure water and pure styrene but that water might enter along a fibreglass strand piercing the styrene enclosure![/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Practical tests performed by HYAB have proved this theory to be valid.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.5.1. Enclosures do not normally form around strands.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The tests showed, that except when damp fibreglass is used (in such cases it is well known that "osmosis" alwaysoccurs), it isnot normal that enclosures are formed around a fibre strand.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Due to the high surface tension of the uncured resin, the "balloon" around the styrene enclosure is deformed by the surrounding glass fibres but seldom pierced, especially where no woven roving is involved.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.5.2. Many FRP hulls have no trigger type enclosures.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A great many FRP boats have no such fatal enclosuresand will consequently not develop "osmosis".[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The fibre strand being "the trigger" solves the other confusing fact, that "osmosis" never affects the gel coat.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]This material always has lots of small styrene enclosures just under the surface close to the water. According to any other explanation the "osmosis" would have started there![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.5.3. Small size hulls less effected than the big ones:[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Looking at the published estimations of "osmosis" among the total fleet, one can clearly see that the percentage of boats affected increases proportionally with the average hull size. Since the 15% reported in 1980 the figures have now reached an estimate of 40%[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The HYAB research, performed at 5 test centers in different parts of the world, now presents a more exact picture of the "osmosis" frequency:[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Hull size < 25´ = 5%, 26´- 40´ = 15%, 41´- 50´ = 30%, 51´- 65´= 60%. As to bigger hulls, so far the HYAB research covers only 6 yachts, all of which were affected.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Regardless of size, hulls containing woven roving mats of over 600 g/m² have a very high "osmosis" frequency. If they also have core material reaching down under the water line, the frequency seems to be 100%![/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.6. Construction faults influence process severity.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]If triggers are present, the number of such styrene/uncured polyester enclosures and the situation determin the speed of the process. If no triggers exist, no "osmosis" will develop regardless of enclosure amount.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Below some of the most common enclosure sources are described.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.6.1. Enclosures emitted from the curing of the gel coat.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Most, not to say all FRP boats made in moulds without post curing have styrene enclosures in the first two layers of FRP.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The enclosures are caused by styrene emitting from the gel coat, which is not fully hardened when the first layers are applied.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A laminate with up to 5% styrene/uncured polyester and dangling chain molecules in the outer laminates and very few enclosures in the inner laminate can be considered as top class.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The existence of "trigger" enclosures is pure chance, which no boat builder can be blamed for![/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]If no woven roving exists in the laminate, an eventual hydrolysis process will mostly be limited to the outer 2-4 layers during at least five years from when the first blisters were noticed.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A peeling and "dry and shield" repair might stop further hydrolysis and blistering but will not restore the loss of bond between fibreglass and resin.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Even in a top class laminate this causes at least 15% less structural strength.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.6.2. Styrene enclosures from disturbed curing.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Disturbed curingis another cause of styrene enclosures. Normally the curing proceeds uniformly right through the material by styrene crosslinkingthe polyester molecules and excess styrene evaporates.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A number of factors can disturb this process. In connection with "osmosis" the most important ones are:[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Draught over the curing surface causes uneven curing from the surface downwards.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]This traps some of the excess styrene inside the FRP and causes styrene enclosures all through the laminate.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Labour welfare acts in the eighties, demanded improved ventilation. Many ventilation systems were built up with suction hoses arranged over the moulds.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Some manufacturers had years of production where a great number of boats "inexplicably" developed "osmosis".[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Later it became evident that the ventilation hoses were placed a foot too deep into the mold and thus caused fatal draught over the surface.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Too much accelerator, re-accelerated resin or too little catalystforce a small part of the curing polyester to "spit out" the styrene meant for the curing during the gelling stage.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The thus uncured polyester again forms a bubble around the styrene and is accordingly enclosed in the cured FRP.[/FONT]

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.6.3. Enclosures caused by moist fibreglass.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Use of moist fibreglass in the productioncreates the worst styrene enclosures.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]The fibres then becomes almost totally coated with styrene and uncured polyester. Takes a long time to form gel coat blisters. Often these are low and as big as hands.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Can also occur on deck and cabin roof areas.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]1.6.4. Styrene enclosures are a property of the material.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]As mentioned before, post curing at 80°C will rid the laminate of such enclosures when the uncured polyester uses part of the styrene to cure and excess styrene evaporates.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]It has been practically impossible, within economical limits, to mould FRP boats from polyester types used before 1990 entirely without styrene enclosures.[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]It is just a property of the material like metal corroding or wood cracking. No one can be blamed for this except those who used damp fibreglass or reaccelerated resin.[/FONT]

Michael Cotton · Jan 2, 2010

We have a C&C 37+. The surveyor found blisters prior to purchase. The owner took the repair price off the selling price. Only 1 shop would gaurantee the repair. The repair shop ground off the entire bottom (5/16"). The bottom was then redone with vynalester(sp?) & epoxy. The shop specialized in blister jobs. There were 5 other boats there for blister jobs. The shop is in Md. Boats were there from Tx, Ma & Canada. Their original estimate was 11K. The finished price was 9K. Then we added an Awlgrip paint job.

estopa · Mar 8, 2010

Maine Sail said:
Barrier coats should always be hot-coated with bottom paint to form a chemical bond. If you don't it looks like this in no time...

How do you do this?

Tim R. · Mar 8, 2010

You need to apply your first coat of bottom paint before the barrier coat completely cures. If I remember correctly, Interlux states that it will not feel tacky but you can leave a thumbprint.

Steve Dion · Mar 8, 2010

Ken:

Has it ever been determined if these blisters are in the paint or gel coat?

If you decide to do it now or later, you should find out what the "real" problem is. If they end up stripping the paint off the boat, you may want to consider the barrier coat.

The no-sand bottom issue only applies to boats that are sanded but no barrier coat applied. If you plan on a barrier coat, it is okay to sand the bottom. There are very few bottom problem on most new boat because of the new products that they use, but I still think a barrier coat is the best way to go.

Ron20324 · Mar 8, 2010

Ken Honeycutt said:
I...it appears that it was VC-17 that was applied by the dealer (not sure of this but it was bluish gray coating when I hauled the first fall).

The blue-ish gray is probably a barrier coat. My new Beneteau had that done by the dealer, too.