Bottom and blisters

Anyone ever start grinding their bottom paint off to do a barrier coat and find extensive hydrolysis?

Started this week and found at least all the matt between the gel coat and roving bad...so bad I can peel 6x6 inch sections off by hand sometimes...

So much for the surveyors opinion/report.....

Anyone get this far and what did you do after grinding and drying????* Yes I've searched the internet and plan on* 1-2 layers epoxy resin then fair, tthen**1-2 layers of cloth/epoxy (not sure yet what I'm gonna use) then 5 coats Interprotect 2000E unless someone convinces me otherwise.

Thanks,

Scott

Here's my report on what I did with my blister problem:


Well, now that Anastasia III is back in the water after about 5 months,
I can post the summary of work done and costs.

Boat: 1986 Krogen 42, hull #99. Had severe blistering when I purchased
her, and planned to do a hull peel and drying to cure this. After a lot
of research, I decided to use the HotVac system to dry the hull.
http://www.hotvac.com/. Seabrook Shipyard did all the work. This was
their first time using the HotVac system, so we all learned a lot. I am
very pleased with their work and the results.

Time: I took her into the yard on Oct. 21, 2002. They started peeling
the hull almost immediately, and started using the HotVac system around
November 15, 2002. While the HotVac folks said it would take a dwell
time of about 6 hrs at 100 degrees C to dry each section, we had to
operate at 80 degrees C because of the Airex PVC coring in my hull. It
took about 18 hrs. /section to dry the hull to acceptable levels. The
HotVac system uses three heat/vacuum pads at a time, each are about 2' x
3' or so. Several areas needed to have the application done 2 or three
times, and a few areas just wouldn't dry, so we had to grind out a few
places and re-fiberglass. The hull was finished drying sometime around
January 13, 2003, about two months. The pads were usually applied and
running 5-6 days a week, sometimes less if the weather didn't cooperate.
While the boat was in a shed, when warm fronts or rain would come
through, the hull would sweat and the pads couldn't get a seal.

We started relaminating new fiberglass on January 27, 2003. Started
applying the first barrier coat on February 24. 3rd. coat of barrier
were put on around Feb. 27. 1st. coat of anti-fouling put on around
March 8. New boot stripe painted around March 18. Final coat of
anti-fouling applied around March 20. A little touchup on bottom paint
on March 25 after lifting off the blocks onto the sled, then splashed on
March 26, a bit over 5 months after starting. I took a LOT of pictures
of all of this, and the automatic date stamp in the digital camera was
very useful, and allows me to give you these dates. I highly recommend
you use one of these for any major project you do.

After peeling and drying the hull, here is what we applied:

3 sessions of 1.5 oz. fiberglass mat with vinylester resin
2 coats Interprotect 1000 - High build epoxy primer
2 coats Interprotect 2000 - 2 part epoxy barrier coat
1 heavy sweep Interprotect VC tar2 - Watertight 2 part epoxy putty
3 coats Interprotect 2000 - 2 part epoxy barrier coat
2 coats antifouling - Petit Trinidad SR (4 gallons).


*


The relamination of new fiberglass was in addition to the bottom job,


and should be considered as an additional expense if you are doing


estimates. Labor was $7100 and materials were $3060. We had to do


this due to the amount of FG we ground off during the peel.

I prepped all the underwater metal except the prop with Petit's
underwater metal kit. This has a two-component acid etching primer
followed by two coats of a tie coat primer. I was disappointed with the performance of this stuff.* The main and thruster props were prepped by the yard with Interlux 260R primer.

Costs:
After doing my hull, Seabrook Shipyard has set their pricing as follows:


*


Complete blister job including hull peel: $250/ft. Sail, $300/ft. Power.


Powerboats are a bit more expensive due to the more complicated hull


shape. However, if you have a trawler with a sailboat shaped hull,


theyll probably charge you the sail price.


*


Use of the HotVac system to post cure (dry) the hull:


$200/day.


Estimated drying times based on a 40 hull would be:


Solid hull (no coring) 20 days.


Cored hulls 40 days.


Different types of coring requires different drying times, so these are only

rough estimates.


My hull was a little less expensive, since it was their first time, and
we were at the bottom of the learning curve.

Although there are many Epoxies that "like" water and can be used with little drying , the best is to dry the boat well.

An East coast boat can simply be brought up to a New England yard and covered for a winter.

In the spring it will be dry enough for your favorite patch system.

FF wrote:

...An East coast boat can simply be brought up to a New England yard and covered for a winter.

In the spring it will be dry enough for your favorite patch system.

Click to expand...

*You're right but make sure there is no moisture in any of the decks and if you have a cored hull make sure it's dry to start with.* You can cause more problems than the blisters you are starting with.** I grew up in New England and we hauled the boats every fall.* Come spring we saw*lots of damage from water and moisture that froze and expanded and then delaminated the cores.

Kieth...

Did you observe how they relaminated the 3 layers of mat??

One at a time or all 3??? How did they actually apply it overhead??? Fully wetted out or tack it to a wet suface???

Thanks...

Scott

Fully wetted out or tack it to a wet suface???

Polly is never a problem , even overhead.

Some Epoxies work better than others , a bit of powder thickiner sometimes helps.

thanks...that's what I thought...just want as much input before I glue my bald head to the bottom of my trawler!!!*

psneeld wrote:
thanks...that's what I thought...just want as much input before I glue my bald head to the bottom of my trawler!!!*

Click to expand...

*That cracks my ass up

I hope I never get a blister.

SD

Click to expand...

-- Edited by skipperdude on Friday 21st of October 2011 03:32:33 PM

I got a bum steer from my surveyor. Bought,...drove her to Charleston from Ft Lauderdale and hauled and stored for 2 months before proceeding to Jersey where i lived on her all summer. Thought I get an early start on a barrier coat this fall...started grinding and discovered pretty bad hydrolysis through the gel coat and first layer or two of mat between gel and first layer of roving.

Any glass boat from the 80's that spent most of its life in tropical waters should be suspect...again without coring, grinding or someone good with a moisture meter...most people including many surveyors are only guessing.

Any glass boat from the 80's that spent most of its life in tropical waters should be suspect.

Actually the problem came much earlier than that , when the price of oil went from $3. BBL to about $15.BBL

Polly went from 15-18c a pound to almost a buck.

By the end of the 70's most mfg had learned to use the crappier resin.

Constant immersion is not the problem , the builders GRP technique would be suspect.

An 80's boat builder with pox/delamination problems would be suspect in many other areas.

I'll buy the resin issue but only to a degree...but can you tell what resin any particular manufacturer used?

I've been following the issue since the 70's too.* My 1977 Cape Dory ketch (first liveaboard) was starting to get blisters even back in the early 80's.* But only on one side.* Though nothing solid, the consensus was that one side cured diffrently than the other...very possible because she was laid up in winter in Conn and that side might have had a much different temp when curing.

Based on my reading of "hydrolysis"...it* IS happening to every polyester resin boat out there...no matter WHAT manufacturer or batch of resin...it just happens at different rates because of different factors...I just got a poster child...AND temperature IS a factor in hydrolysis.



-- Edited by psneeld on Saturday 22nd of October 2011 06:02:29 AM


-- Edited by psneeld on Saturday 22nd of October 2011 06:06:01 AM

They did it one layer at a time. Here are some pix.

Thanks Kieth...looks the same....back to grinding for another week. Only 1/4 done grinding as it's slow go. Dread doing all the glass work...but realizing piecemeal might be slower going but less chance of major issues...glad to see othr pros doing the same even with more than 2 hands to do the work.

Scott,

Would you rather be re-fastening a wood boat * ...or replacing a few planks?

I think I would.

Fortunately this should be a one time deal where a wood boat has maintenance*every year...at least my repair should last 50 more years if the bad polyester job lasted*25 years!!!

*

But yes a couple planks would feel like a dream right now!* even just a touch up recaulking job...now where's that caulking iron I just laid down????

Unfortunately I wasn't present for the survey...timing and distance..

Yes the surveyor should have seen this a mile away...though I did give him some latitude in his report so the insurance company wouldn't keep me from moving the boat the day of my final sale.

The surveyor even called me the minute the boat came out of the water...and was worried...I said well go ahead and finish the survey (I'll pay full price ) and take another look at the end of the haulout to see what you think then.* Well what I was told..." it must be the paint because they went away after being out of the water for a couple hours." I knew the paint job was old because the owner dove to keep the bottom clean instead of painting...

When I hauled the boat almost a month later I knew I had some blisters but it didn't look that bad.* Not till my end of season haul and starting with the grinder.* Which I guess is typical for hydrolysis...you can have it and not have blisters but if you have blisters...you definitely have hydrolysis.* Sometimes blisters don't form or have a lot of pressure in them because everything has become so porous there's no pressure buildup.* Seems like that is my case...there is evidence that there was some blister repair previously (never mentioned by previous owner)...but the hydrolysis is bad enough that I can easily get a chisel under the gel coat in some places and just push off long strips of the gel coat and what's now resin dry mat.* The layer or two of mat over the roving is in several stages of being washed out...but the roving is still good...which is what is clearly understood about hydrolysis...mat will wash out quickly because of it's nature while cloth and roving resists it a bit better (less wicking).

The only real way to check for hydrolysis and how bad it is is to core or grind.* Moisture meters only tell part of the story from what I'm told and from peractical experience I don't trust many people who use them.

Well after a week of grinding...I'll be near or half done grinding...I itch and my arms ache..but it will feel great once I start adding glass and epoxy...knowing once again I can fix something the bozo manufactures couln't get right gthe first time.

Go after the surveyor???* No...I'll just never use another one as I've used 3 and all 3 found way less than they should have and less than I did in the same amount of time that I looked around....


-- Edited by psneeld on Monday 24th of October 2011 06:12:35 PM

These pix will make you cringe. The blisters at survey, then what they look like as you start peeling them. I can't speak highly enough of the HotVac system.

Try slamming a chisel into your bottom and prying off 10 by 10 chunks of glass and gel up to 2 layers thick!* Not for the weak hearted!!!

**

Don't know if my experience will help much as I didn't have the de-lamination issue you have. I found 150 blisters on haul out, most the size of a quarter or smaller. I ground them out using a hand grinder and ablative type grinding wheel. I ground out each blister wide and deep enough that I hope got all the moisture. I did not let the ground out blisters dry more than a couple of weeks and some a bit less than that. I then filled each ground out cavity with West Systems Six-10 epoxy, an easy to use 2 part epoxy that comes in a caulking tube and auto mixes as you use it. I had to refill most twice as the expoxy shinks a little after it drys sanding to roughen between fills. A final sanding and 2 coats of primer and 2 coats of paint and I was done.

Some suggested I apply a barrier coat, but decided against it and see how just filling the bilisters would work. 6 months later, so far so go.

Tim,

I do just about exactly the same. Use a slightly different West System epoxy and consider it a barrier coat. Then sand and apply bottom paint. Do'nt consider this a big issue ...just a bit of a nuisance.*

So when I bought my boat (1987 TT) surveyor said no issue with blisters -- when I hauled and painted the bottom a month or so later, I saw a few areas of tiny blisters (1-2mm diameter) that did not deform the bottom at all. I painted and splashed. I plan on stripping the bottom of many coats of bottom paint sometime next year (probably soda blasting) but should I do anything else about these tiny blisters, i.e. sand/grind down and apply barrier coat?

Thanks,
dvd

I suggest that any boat from the 80s grind a fairly substantial area around a place where there are several blisters. My boat had some blister work done at some point and it looks like someone even tried a weak attempt at a barrier coat...which I think the combo of a bad patch job and poor barrier coat actually accelerated all my damage.

If you want an eye opener...research hydrolysis on the internet...after several articles and looking at some boats...you get the point...I have already noted some boats in my marina that show small patches of it that the owners couldn't believe...I have been seeing it for years in varying degrees and never quite knew the whole process....well my boat has brought it home.

if you think you can let a bad bottom go a few more years..well you might..if up north in cooler water and letting it dry every winter a few months.

if you leave her in the water and are in Florida like waters...even a few years can spell the delamination of several layers of fiberglass from your entire bottom...don't believe me...look at the chisel and chunking of my bottom...you'll believe...

Scott, I saw the de-lamination on a 30 yo sailboat in the yard when I was doing my bottom. I think from what I've seen the serious de-lamination that you're experiencing is somewhat rare. Blisters however are not. With serious de-lamination like the sailboat I mentioned, the entire hull was having to be relaminated and glassed. I think the owner mentioned about 20-30 grand for the re-glassing. Nearly half the value of the boat. Perhaps your problem is a bit different, but it sounds similar. Again I think this is rare but for you it doesn't matter how rare it is. Sounds like you've done your research. Good luck with it and let us know how you proceed.

As Eric mentioned blisters at least here in FL are viewed either two ways. Fix before it gets worse, or forget about it. The mechanic at the yard I used suggested repairing all the blisters then blasting to remove all the bottom paint. Then apply a barrier coat. I choose not to do the barrier coat. Time will tell if that was the right decision.*

My research led me to a lot of reading on hydrolysis...what I am saying is the point that my boat is isn't all that rare....especially boats in warm water all year.

Hydrolysis is going on with or without blisters on most all boats. ALL fiberglass is absorbing water and slowly dissolving...don't believe me...go into sites that just make fiberglass tanks and pipelines...they are sayinjg the same thing.

The trick is to slow the process...thus all the newer boats have some or all layers of their hull vinylester resin.* So my reworking will be remove most of the bad glass (starting to get scared as some places I'm into 2 layers of roving that have weak bonds), then a coat of epoxy,* fill deep grinds with glass cloth,*fair with epoxy fairing*mix, one layer of polyester cloth and epoxy, then 4-5 coats of Interlux Interprotect 2000*

*

*

Getting my bottom stripped and painted. Tk God, no blistering or de-lamination so lucky I guess. Also having the runners done too.

Elwin*

I'm late to the game but the info in this thread is great! I'm looking at various 80's trawlers and one I like has blisters as well as some hull deflections. Sounds like a full peel can tip the scales at 20k or more... and the deflection fix just adds to it... ouch!

Keep looking,

Disappointing when u hear so much praise for the kk42 and then bump up against hull issues like this, that other 42's also have. I can probably negotiate the price somewhat, and the decks are already done, but i spotted rot at the base of the forward engine room bulkhead (glass separated from the ply) what other gremlins lurk that would be difficult to identify without doing destructive investigation... e.g. tanks, etc. The Lehman has low hours and doesn't smoke at all from a cold start, which seems like a plus to my uneducated eyes.

David Pascoe's page has the best information on blisters that I have seen.