Hull blisters worse on some model years?

Hi,
The bottom is getting a full job to remove a bunch of blisters on an 83 KK42, the company doing the work told me because everything was stripped down to the glass (not to the core btw) and re-epoxied followed by traditional bottom treatment I shouldn't have any blister issues again, the whole job is a 3 month ordeal.

My concern is that im not convinced the blisters are coming from water penetration versus an issue with the resin used on the KK42. Does anyone have any experience or thoughts? Do these types of repair jobs really last or is the only option to strip the outer glass to the core and reglass?

I'm new to cored hulls so any advice is appreciated.
Thank you,
Arthur

Ask for a written guarantee.

I'll have that, just was curious if owners had seen differences in model year? Especially with how many different builders/processes were used to build these over the 20 years.

boatpoker said:

Ask for a written guarantee.

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It is only my opinion, but I highly doubt any boat yard would give you one. There are just too many variables that could leave them exposed to liability.

Like any bottom job and bottoms, they are going to always be hit or miss. I don't think anyone could (or should) make general statements regarding this model or a certain construction technique being more susceptible to blisters or not.

While we didn't get a peel job, on our old boat, we got a sand blasting and skim coat of epoxy put on, we had many hundreds of pock blisters, but hindsight being 20/20, I wouldn't do it again and am glad we sold the boat shortly after. I have a feeling they will come back, but hey... I could be wrong.

Yes, and to be specific anything in writing only covers workmanship and material defects, I don't think any yard would do a "no blisters" guarantee.
That goes to the core of my question, are there resin/build issues causing these or is it usually water penetration? If they are issues in the build no recoat will ever help.

Tom.B said:

It is only my opinion, but I highly doubt any boat yard would give you one. There are just too many variables that could leave them exposed to liability.

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I agree but I still think the yard should be asked. I have seen many, too many epoxy bottom job failures however, Steve D'antonio who shows up on this forum on occasion says he has never had one fail and did offer guarantees when he ran a yard.

I was given a 10yr warranty against any blister reoccurrence, the only exclusion was around thru hulls for obvious reasons.

Arthurc said:

Yes, and to be specific anything in writing only covers workmanship and material defects, I don't think any yard would do a "no blisters" guarantee.
That goes to the core of my question, are there resin/build issues causing these or is it usually water penetration? If they are issues in the build no recoat will ever help.

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All the above. Yes, there are occasionally issues with resin. I've seen them on smaller boats so severe that the boats had to be recalled and replaced by the builder. However, barring those situations more issues are with application than materials.

IT usually is tbe resin that allows or encourages the water absorption.

So it is a crap shoot.

Usually the vast majority of blisteringoccurs in tbe mat between the roving and tbe gel coat.

So after the matt is removed, you now have a good view of how good or bad the laminations are deeper.

Regarding your Question a few points:

1) The hull should have been dried and checked with a good quality moisture meter operated by a knowledgeable operator: Yes/No

2) After normal preparation processes and confirmed dry the 2 Pack Epoxy Resin should have applied as first coating then preferably prior to full cure a second coating applied

3) Again after preparations (if fully cured) three-five coatings of a suitable Epoxy Primer/Osmosis paint should have been applied (Again preferable to coat each time prior to full cure) such as Internationalhttp://www.yachtpaint.international/en/product/287/International-Gelshield-200-Osmosis-Treatment-A+B-2,5-Lt-Green-YPA212-458COL678.html

OR https://international-yachtpaint.com/en/au/boat-paint-products/primers/interprotect

If those scenarios look like your treatment you should have no real issues, I have under taken dozens of such treatments and touch wood not one (some 10 years on) have ever had an issue


Cheers Steve (MIIMS Surveyor) Lloyd's Maritime

If you search "blisters" and user name "Keith" you will find some info regarding blister repairs on an '86 Krogen. Here's one thread:


http://www.trawlerforum.com/forums/s32/bottom-blisters-4609.html

I have been interested in hull building material for the 50+ years that I have been involved with boats. I have heard all the hype about which building material is best. Each material has its up and down sides. For each material there are always some over enthusiastic supporters. Here is an example of the down side of the fiberglass materials. True, proper build methods could and more often than not avoid the blisters and delamination issues. Careful and knowledgeable build methods with any material are needed to avoid the down side. The blister and decontamination issues in older boats are particularly troublesome because once they occur you are never sure how far it will go and if a repair will ever be enough. I think it has been said before with blisters it is a crap shoot. Given the option I chose epoxy to hold things together whether it be wood or glass.

Arthurc said:

Hi,
The bottom is getting a full job to remove a bunch of blisters on an 83 KK42, the company doing the work told me because everything was stripped down to the glass (not to the core btw) and re-epoxied followed by traditional bottom treatment I shouldn't have any blister issues again, the whole job is a 3 month ordeal.

My concern is that im not convinced the blisters are coming from water penetration versus an issue with the resin used on the KK42. Does anyone have any experience or thoughts? Do these types of repair jobs really last or is the only option to strip the outer glass to the core and reglass?

I'm new to cored hulls so any advice is appreciated.
Thank you,
Arthur

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My experience has been upon purchase I have the bottom sanded then epoxied and have never had any blister issues since. I think the key here is to break the chain, in order for blisters to form there must be a pathway for water to permeate into the glass and the epoxy pretty much stops this if properly applied.

Water can get in through the bilge.

Epoxy is way more water resistant but not totally, barrier coats claim to be, but I havent ever read a detailed report on them, just manufacturer claims.

On a cored boat, if there is water anywheres in the coring that can migrate, blisters can form.

Just sanding the bottom and barrier ciating, unless fresh from the factory and never dunked, can be the worst thing to do, unless the hull is guaranteed dry enough.

Boats from the late seventies and early eighties reportedly suffered from bad resins. I had a 1977 Cape Dory 30 Ketch that blistered like crazy on one side yet not the other. Sure there could be a few different reasons but resin curing certainly looked like a good possibility.

psneeld said:

Water can get in through the bilge.

Epoxy is way more water resistant but not totally, barrier coats claim to be, but I havent ever read a detailed report on them, just manufacturer claims.

On a cored boat, if there is water anywheres in the coring that can migrate, blisters can form.

Just sanding the bottom and barrier ciating, unless fresh from the factory and never dunked, can be the worst thing to do, unless the hull is guaranteed dry enough.

Boats from the late seventies and early eighties reportedly suffered from bad resins. I had a 1977 Cape Dory 30 Ketch that blistered like crazy on one side yet not the other. Sure there could be a few different reasons but resin curing certainly looked like a good possibility.

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your absolutely correct, thank you for catching my error. I forgot to mention I would dry the hull in a boat yard until they could no longer get an h2o reading before epoxying the hull. You can do it yourself to save money. Even with bad resin or not properly laid I believe if you dry your hull< assuming your hull is still sound> totally they epoxy her she will go for a lot of years until she has problems.

Vinylester seems to get used in some new builds as the outer layers. Costs less,? does the job. Anyone with experience of using it?
A friend with an old steel boat he lives aboard(he was PAID 5K by its owner to take it),he treated his hull with multiple coats of something he calls "epoxy tar", just looks like black epoxy to me. It seems to have a degree of anti fouling properties too.

Had Daydream pulled last year...literally 1 small blister after sitting in same berth for 20 years. Sand blasted, barrier coated and bottom painted.... 1982 must have been a good year for KK42 resin.

BruceK said:

Vinylester seems to get used in some new builds as the outer layers. Costs less,? does the job. Anyone with experience of using it?
A friend with an old steel boat he lives aboard(he was PAID 5K by its owner to take it),he treated his hull with multiple coats of something he calls "epoxy tar", just looks like black epoxy to me. It seems to have a degree of anti fouling properties too.

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Hi,

Nordic tug and may be AT uses vinylester, Hull guarantees 10y also blisters. I still have a year of warranty time, I have not noticed anything to be repaired in my NT.

In fresh water, there is a risk for blisters a larger than salty because the surface tension is smaller and penetrates GRP more easily.


I have the impression that blisters have more appearance than the question does not affect the strength of the Hull structure because the vesicle is formed only on the surface so is it worth paying for a repair that may recur?

NBs