KK39 Blisters

Looking to buy a 2000 KK39. Survey revealed numerous quarter sized blisters, (50 to 100), on both sides. A few are just under the new bottom paint but the majority are deeper. I was disappointed the owner did not volunteer the information which he admits he was aware of.

Is blistering a KK39 common issue? The owners ad is an excerpt from the manufacturer which states due to the lay up they are protected from blisters. He actually had that in his ad while knowing the bottom was covered in blisters. Lesson learned: don’t trust anyone even if they proclaim to attend church regularly.

Is blisters a common problem with 2000 KK39’s?
Should I walk away or buy and repair. A yard quoted $8K to $10K.

Be careful that the "blisters" are not actually [primarily] simply that bottom paint of its many layers thickness has separated from the bottom's surface.

I say this because I know that can happen... wherein the paint layers are so thick that blisters of [under] the paint itself can appear as the blisters must be from fiberglass layers separating.

Check carefully!

Just saying a word of caution and wishing you best luck in direction you decide to go.

My surveyor did the "mash test". some but very few were soft which he determined were just water under the paint but most were hard which he determined were actual blisters. Did not want to do any destructive testing....yet.

Not sure if it means anything. When we clamped the shorepower cord, we got a really high reading. The surveyor said it may be an issue but could also be an adjacent boat. I mention this because someone said if indeed the boat has that type drain it may effect the paint. They were NOT an authority but thought would pass it on.

Many many boats have blisters. Many many yards have made a lot of money repairing blisters. I don't think anyone has a verified, documented case of a boat sinking due to blisters.

Some of the older KK builds had issues with blisters that could saturate the core. Krogen changed the core materials significantly to a synthetic foam that won't rot even if water intrusion occurs.

Our 1991 KK has some blisters. Maybe 40. Many are just bottom paint, some will require grinding out and glass/epoxy repairs...an easy job doing a little at a time at each haul out.

First question I would ask, how is the rest of the boat? Is it exactly what you want and in great condition? Is it just ok and needs other work? If you really like the boat overall and it is in great condition then maybe proceed. However be prepared to spend way more that the $8 to $10K to fix it. It will be an unknown until you start stripping it to bare glass. You could end up peeling the whole boat below the waterline. Not saying that you will but it could happen. I have done blister repairs on several boats and it has never been less work than I thought it would be, always more work. Just keep your eyes open if you do proceed. Particularly if it is cored below the waterline. Negotiate the price aggressively.

Our 1977 Tolly is currently hauled. Yeah, there are some bottom blisters... it is 44 yrs old!

Some pronounced ones we corrected. The "littles" we left alone. I know our boat's bottom ranges from 1" to 2" thick of well constructed fiberglass; she leaks not a drop of water. IMO, for boats made of originally good fiberglass materials and accountable professional layup methods, bottom blisters are the natural course of aging and should be dealt with accordingly. But, we should not drive ourselves nuts over the fact that blisters can and most likely will occur.

Of course... some boat builders' layup procedures and materials used were not of the highest quality. Those can develop overriding blister problems that should be dealt with in manners that may be necessary.

A few boats ago, my boat had blisters. Solid fiberglass bottom, so no concern about rotting the core, and based on research, I was persuaded there was not threat to the structural integrity of the hull. I paid a guy to grind them out, refill them, put an epoxy barrier over them, and no bottom paint. At my next haul out 3 years latter, there were a few new blisters, which were fixed the same say. At the third haul, there were virtually no blisters.

If the hull is cored below the water line, I would probably walk on the assumption that water has found its way in and will be much more work to fix that it appears.

If it’s a solid glass hull then I would double the high estimate, and assume 2 months hauled in a yard to repair. Repairs ALWAYS run over. It’s just a question of how much. With that in mind, what’s the boat worth to you?

Show me an older boat that doesn’t have blisters. Southerly just went through a haul out survey. Some blisters that can easily be taken care of on her next bottom paint. 4” hull. No concern.

Donna said:

Show me an older boat that doesn’t have blisters. Southerly just went through a haul out survey. Some blisters that can easily be taken care of on her next bottom paint. 4” hull. No concern.

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4" hull? Impressive!

Ours hits multi inches at specific locations such as bow stem to keel junction, keel at its center stern area and also at specific points of stringers to hull attachment. On the flat areas the bottom's generally 2" +/- becoming 1" + as it traverses from bottom to sides.

Blisters were common in boats constructed prior to the mid-90s. The use of isophthalic resin for the first few layers of fiberglass pretty much got rid of them. Can there still be lay-up flaws in a hull? Sure. But widespread blisters should be rare in a well constructed hull from the mid-90s on.

Airstream345 said:

Many many boats have blisters. Many many yards have made a lot of money repairing blisters. I don't think anyone has a verified, documented case of a boat sinking due to blisters.

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I agree totally. Never heard of any boats sinking due to blisters. Just keep an eye on them. Most Taiwanese boats from the 80s and 90s have some blistering.

Here's a related thread: https://www.trawlerforum.com/forums/s32/bottom-blisters-4609.html

There are many in the archives.

Rufus said:

Here's a related thread: https://www.trawlerforum.com/forums/s32/bottom-blisters-4609.html

There are many in the archives.

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I well recall that thread. Some blister jobs can be big. Some not so much.

May I suggest that searching this question on the Kadey Krogen site…. Krogen Cruisers…..where only answers from Krogen owners should give you the answers that you need. I don’t believe that any KK39 which were only built from 1999 to 2008 had any coring below the water line. That is the first thing you need to verify. Then talk to Krogen owners.
The site to become a member of would be Krogen Cruisers.
Good luck. We love our KK39 “Kindred Spirit “ hull #42 2004
Al

Divealot said:

My surveyor did the "mash test". some but very few were soft which he determined were just water under the paint but most were hard which he determined were actual blisters. Did not want to do any destructive testing....yet.

Not sure if it means anything. When we clamped the shorepower cord, we got a really high reading. The surveyor said it may be an issue but could also be an adjacent boat. I mention this because someone said if indeed the boat has that type drain it may effect the paint. They were NOT an authority but thought would pass it on.

Click to expand...

I can't think of any scenario that would cause bottom paint to blister as a result of being plugged into shore power...there is no "circuit" per se as the hull is FRP. You can get paint failure around bonded underwater hardware as a result of leaking AC current or cathodic over-protection, but not blisters.

Divealot said:

Looking to buy a 2000 KK39. Survey revealed numerous quarter sized blisters, (50 to 100), on both sides. A few are just under the new bottom paint but the majority are deeper. I was disappointed the owner did not volunteer the information which he admits he was aware of.

Is blistering a KK39 common issue? The owners ad is an excerpt from the manufacturer which states due to the lay up they are protected from blisters. He actually had that in his ad while knowing the bottom was covered in blisters. Lesson learned: don’t trust anyone even if they proclaim to attend church regularly.

Is blisters a common problem with 2000 KK39’s?
Should I walk away or buy and repair. A yard quoted $8K to $10K.

Click to expand...

Hi... we own a 2000 KK 39 and as far as I know, blisters are not common. I wonder how the owner cared for maintaining his bottom. Ours is in great shape and I have never heard of other KK 39's having problems with blistering.

C. Herro
Albatross
KK39 -19

Donna said:

Show me an older boat that doesn’t have blisters. Southerly just went through a haul out survey. Some blisters that can easily be taken care of on her next bottom paint. 4” hull. No concern.

Click to expand...

While it's true many older (and some new) vessels suffer from blisters, I have hundreds of photos of old bottoms that are free of blisters, it is by no means a forgone conclusion for an older vessel.

Osmotic blisters occur for specific and well-understood (unfortunately not by enough folks in the marine industry) reasons, primarily having to do with the presence of water soluble materials and water permeable polyester resin. Vessels that use vinyl ester, vinyl ester skin coats or epoxy bottoms are essentially blister-proof. Epoxy barrier coats, if properly applied, can also provide years' of protection from osmotic blisters.

There are blisters and there are blisters. I routinely encounter blisters on vessels adjacent to thrusters and shaft logs, those are the result of using fairing compound that was not rated for below the waterline use. It's not a serious problem and relatively easy to fix.

Wholesale, bottom-wide blisters on the other hand are often the result of classic osmosis issues. Unless the blisters are very large and very deep, it's unlikely they will pose a structural threat, but it's impossible to make this determination with a visual analysis alone. They will have an impact on the vessel's resale value unless you pay to have them repaired, and doing so correctly, by peeling and relaminating with VE resin, is costly. Spot repairing blisters, i.e. grinding and filling, is addressing the symptom and not the cause. Spot repairs are a cheaper option, but more blisters will almost certainly continue to reappear.

I would not necessarily walk away, but you should have the bottom assessed by someone who is very knowledgeable on the subject, preferably one who has undertaken repairs. Only mildly destructive testing (doing what's known as a "patch test") can provide an accurate analysis and quote for repairs.

For more on analysis, repair and prevention techniques, see https://stevedmarineconsulting.com/wp-content/uploads/2014/03/Blistology-Pt-1-PMM-Jul_Aug-06.pdf

Steve - That's a great "Blistology" layout/document! Thanks!! I have the address in my boat folder.

I have a 1998 kk39, hull #1. My boat has no blisters at time of surveying 2 years ago. I would bet that it is only under the bottom paint. These are very well built boats and I still marvel at how well built they are! You won’t be sorry with the purchase. I love mine!

Chris

Donna said:

Show me an older boat that doesn’t have blisters. Southerly just went through a haul out survey. Some blisters that can easily be taken care of on her next bottom paint. 4” hull. No concern.

Click to expand...

Our 1976 Taiwan built Bluewater has not experienced blisters in it's life.

I checked for moisture at each haulout and there was no moisture intrusion.

During the last haul out, the bottom had to be taken down to gel coat because of the buildup of non ablative paint. I epoxy coated the bottom at that time since the boat bottom was completely free of paint. Even though the bottom did not suffer blisters, I felt applying epoxy was a good primer-tiecoat and insurance against water intrusion.