Hull blisters, Oh My!

[Sue Bradford]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

[chuck yahrling]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue;

Are these just on the wetted part of the hull, or on the topsides as well? I'm working with some ooze spots on my hull, down on the keel.
Does the purple stuff look a bit like rust (mine does) or is it truly purple?



yahrling@cybertours.com

[Dana]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

_____________________________________________________________________


Sue,

I know this is very stressful but believe me (if you can at this time) that the picture is not as black or expensive (if you are willing to do the work) as you might think.

I am assuming that the boat is pulled now for the winter. I would suggest that the blisters be opened while you can still see them. By opening I mean you should "pop" the blister and the thin gel coat layer is cut out with a knife over the blistered area. You should only find purple wet mat under the gel coat and the actual fiberglass laminate under the gel coat should not appear to be affected. Clean the exposed laminate with the tip of a rag which has been wetted with acetone. Avoid getting the acetone on the surrounding bottom paint because it will smear all over the place.

The acetone will do two things...one is to start to dry the affected area....the other is it will remove the impurities from the area.
Now comes the hard part.......leave the areas exposed over the winter and take the questions (and looks) of everyone who passes by the boat.

The only question to consider during the winter is whether you want to strip the paint off the bottom of the boat completely in order to discover other blisters not seen before or to apply a complete barrier coat......or repair the exposed blisters and apply a barrier coat only to those spots. If this is a case of hundreds of blisters where most of the bottom paint must come off, then I would suggest the paint be all removed and a very good epoxy barrier system such as the West System be used. My slip neighbor had a very bad case (hundreds) appear all of a sudden on his thirteen year old boat (not a CD). He followed these steps and has not had a single blister appear in over two years now. It is bad news but not the end of the world, you can fix this at small cost if you do it yourself with a very good chance that this will not happen again or be much smaller in magnitude. I have yet to find a yard which will guarantee that blisters will not reoccur.

Let me know and I can tell you what the remaining process of the repair procedure would be in the spring if you decide to do it yourself.

Dana



darenius@aol.com

[David Sabourin]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue,
I'm the owner of CD36 hull#151 built in '87. This past summer when I hauled for my annual bottom paint, zinc etc. the yard advised me I had several blisters. We tallked about how this could be corrected and why it should be corrected. We decided to haul the boat for the winter (I usually leave it in the water all winter) and peel the bottom. Let it dry aver the winter and in the spring put a barrier coat on. After the peeling process, we dicovered the whole "chop coat" was purple in color. So we hand ground it off with a soft grinder. This purple color is caused by (cobalt) not having cured properly. Cape Dory was trying to push out as many hulls as possible then and might not have had the technology to speed this curing process. I have further decisions to make as to barrier coat product and whether to apply a layer of glass to replace the chop coat. The experts advice and cost will determine the direction I go. I'll be glad to keep you posted as to the progress via e'mail if you like.

Right now the MadHatter is sitting high and dry looking a little embarassed with her bottom showing.

Good luck, HAPPY HOLIDAYS,
David Sabourin



hatter11@erols.com

[Sue Bradford]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue;

Are these just on the wetted part of the hull, or on the topsides as well? I'm working with some ooze spots on my hull, down on the keel.
Does the purple stuff look a bit like rust (mine does) or is it truly purple?

Chuck;

They are mostly in the keel area, all below the waterline, and definitely purple- almost dark blue. Thanks for the response. Truly, this site is great.

[Sue Bradford]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue,
I'm the owner of CD36 hull#151 built in '87. This past summer when I hauled for my annual bottom paint, zinc etc. the yard advised me I had several blisters. We tallked about how this could be corrected and why it should be corrected. We decided to haul the boat for the winter (I usually leave it in the water all winter) and peel the bottom. Let it dry aver the winter and in the spring put a barrier coat on. After the peeling process, we dicovered the whole "chop coat" was purple in color. So we hand ground it off with a soft grinder. This purple color is caused by (cobalt) not having cured properly. Cape Dory was trying to push out as many hulls as possible then and might not have had the technology to speed this curing process. I have further decisions to make as to barrier coat product and whether to apply a layer of glass to replace the chop coat. The experts advice and cost will determine the direction I go. I'll be glad to keep you posted as to the progress via e'mail if you like.

Right now the MadHatter is sitting high and dry looking a little embarassed with her bottom showing.

Good luck, HAPPY HOLIDAYS,
David Sabourin

David;

I'd love to hear how work on the Mad Hatter progresses! Thanks, and Happy Holidays to you, too.

Sue

[Sue Bradford]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

_____________________________________________________________________


Sue,

I know this is very stressful but believe me (if you can at this time) that the picture is not as black or expensive (if you are willing to do the work) as you might think.

I am assuming that the boat is pulled now for the winter. I would suggest that the blisters be opened while you can still see them. By opening I mean you should "pop" the blister and the thin gel coat layer is cut out with a knife over the blistered area. You should only find purple wet mat under the gel coat and the actual fiberglass laminate under the gel coat should not appear to be affected. Clean the exposed laminate with the tip of a rag which has been wetted with acetone. Avoid getting the acetone on the surrounding bottom paint because it will smear all over the place.

The acetone will do two things...one is to start to dry the affected area....the other is it will remove the impurities from the area.
Now comes the hard part.......leave the areas exposed over the winter and take the questions (and looks) of everyone who passes by the boat.

The only question to consider during the winter is whether you want to strip the paint off the bottom of the boat completely in order to discover other blisters not seen before or to apply a complete barrier coat......or repair the exposed blisters and apply a barrier

[David Sabourin]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue,
I'm the owner of CD36 hull#151 built in '87. This past summer when I hauled for my annual bottom paint, zinc etc. the yard advised me I had several blisters. We tallked about how this could be corrected and why it should be corrected. We decided to haul the boat for the winter (I usually leave it in the water all winter) and peel the bottom. Let it dry aver the winter and in the spring put a barrier coat on. After the peeling process, we dicovered the whole "chop coat" was purple in color. So we hand ground it off with a soft grinder. This purple color is caused by (cobalt) not having cured properly. Cape Dory was trying to push out as many hulls as possible then and might not have had the technology to speed this curing process. I have further decisions to make as to barrier coat product and whether to apply a layer of glass to replace the chop coat. The experts advice and cost will determine the direction I go. I'll be glad to keep you posted as to the progress via e'mail if you like.

Right now the MadHatter is sitting high and dry looking a little embarassed with her bottom showing.

Good luck, HAPPY HOLIDAYS,
David Sabourin

David;

I'd love to hear how work on the Mad Hatter progresses! Thanks, and Happy Holidays to you, too.

Sue

Sue,
Please send me your e'mail address so we can communicate without having to gothrough CCDOA.

David



hatter11@erols.com

[chuck yahrling]

We've got blisters and purple ooze, to an alarming extent on our newly purchased CD28 sloop (1985). We are obviously pretty distressed, especially as we had the boat "professionally" surveyed and only one blister was noted. But now the questtion is, what to do? There seems to be debate in the fiberglass world about what the right thing to do is. Strip the gel coat, or not? Epoxy? New gel? We do not want to sell the boat anytime soon, we love it, blisters and all. One of us is very handy with hands, tools, materials, etc, and could probably repair several to many blisters a year. Opinions? Thanks!

Sue;

Are these just on the wetted part of the hull, or on the topsides as well? I'm working with some ooze spots on my hull, down on the keel.
Does the purple stuff look a bit like rust (mine does) or is it truly purple?

Chuck;

They are mostly in the keel area, all below the waterline, and definitely purple- almost dark blue. Thanks for the response. Truly, this site is great.

Following the suggestions I got here and elsewhere, I drilled small dimples into each weepy or cracked spot with a 1/2" drill - not too deep, just enough to spall away the damaged gel coat and reveal laminate below. In some spots I also drilled 1/8" holes thru to the lead keel. This was recommended as a test to see if water was in the keel cavity. So far, no visable water...

In all cases the laminate was the expected pale green color. In a few cases, the rusty-purply color returned after a few weeks, but disappeared again after I scraped it out of the dimples. I'm leaving the opened spots to dry over the winter.

I plan to fill the dimples with 3M vinyl ester patch material, then paint the whole underside of the hull with 3M water barrier [requires stripping the Trinadad bottom paint, which BTW goes pretty well with Petit Paint and Varnish remover for f/g hulls (aka methylene chloride) - even in 30-degtree weather!] I'll do the filling, sealing and bottom painting just before launching in April-May.

Maybe it's wishful thinking, but I'm proceeding on the the theory that no radical water penetration behind the gel coat is responsible for these belmishes. I think I have just a combo of normal osmosis from old-age and maybe some kinda spilkus from Cape Dory experimenting with different construction methods.



yahrling@cybertours.com

[Larry DeMers]

Sue,

The purplish color is due to uncured resin (due to poorly mixed resin/hardener) absorbing water, and forming an acid which has the purple color. You caught these puppies just in time, as the color purple can indicate advanced penetration into the matrix.
You did the right thing in opening up the blisters, although I would suggest making a plastic tent in the spring, and adding heat to the solution. You want to drive the moisture out, or you will be doing this all again soon. Be sure to open all suspicious sites and allow them to dry out. I would recommend the epoxy overcoating followed by the barrier coat of your choice.

The reason for this happening to late model CD's is at least partially due to CD eliminating their Quality Control people/person in the last months of CD's existance.

Good Sailing!

Larry DeMers

Sue;

Are these just on the wetted part of the hull, or on the topsides as well? I'm working with some ooze spots on my hull, down on the keel.
Does the purple stuff look a bit like rust (mine does) or is it truly purple?

Chuck;

They are mostly in the keel area, all below the waterline, and definitely purple- almost dark blue. Thanks for the response. Truly, this site is great.

Following the suggestions I got here and elsewhere, I drilled small dimples into each weepy or cracked spot with a 1/2" drill - not too deep, just enough to spall away the damaged gel coat and reveal laminate below. In some spots I also drilled 1/8" holes thru to the lead keel. This was recommended as a test to see if water was in the keel cavity. So far, no visable water...

In all cases the laminate was the expected pale green color. In a few cases, the rusty-purply color returned after a few weeks, but disappeared again after I scraped it out of the dimples. I'm leaving the opened spots to dry over the winter.

I plan to fill the dimples with 3M vinyl ester patch material, then paint the whole underside of the hull with 3M water barrier [requires stripping the Trinadad bottom paint, which BTW goes pretty well with Petit Paint and Varnish remover for f/g hulls (aka methylene chloride) - even in 30-degtree weather!] I'll do the filling, sealing and bottom painting just before launching in April-May.

Maybe it's wishful thinking, but I'm proceeding on the the theory that no radical water penetration behind the gel coat is responsible for these belmishes. I think I have just a combo of normal osmosis from old-age and maybe some kinda spilkus from Cape Dory experimenting with different construction methods.

demers@cray.com

[Joe Butler]

Hi,

This may be a silly question, but does anyone know of a boat that has actually sunk, leaked, or become structually unsound due to blistering of the hull?

I ask because some of the solutions for blistering seem extreme and expensive...and I have a 20 year old Alberg that has probably had the same blisters for about 18 years!!!

Joe Butler



h.j.butler@tcu.edu

[Dana]

No, it is unusual for blisters to "sink a boat". There are probably more cases of delaminations in boat decks than there are major structural failures due to hull blisters. CDs have always been lucky that blisters appear only be to cosmetic between the gelcoat and laminate but never in the laminate.

Very large blistering into the laminate on other boats has been known to happen. For this reason it is important to know what the degree of blistering is and if it is affecting the laminate.

For a moderate case of blistering, the cost of maintenance is low. It is just time consuming. Many people refer to the annual spot repair "as you see them" as "PAY AS YOU GO". I adopted this method ten years ago and one can see a dramatic decrease in the number from year to year. I had started with hundreds and I did a complete boat redo with drying, barrier coats , etc. after the first year. The next year I had just as many. I had used the Interlux barrier system.

Since then I have adopted the pay as you go and switched to sealing the blisters with two part epoxy after sealing the laminate with the West System. I noticed that the number of blisters began to be half the amount each year. I pulled the boat after 3-1/2 years this last winter. I had only about a dozen. With that amount over that time period, they are now only part of my bottom maintenance.

Dana

Dana

Hi,

This may be a silly question, but does anyone know of a boat that has actually sunk, leaked, or become structually unsound due to blistering of the hull?

I ask because some of the solutions for blistering seem extreme and expensive...and I have a 20 year old Alberg that has probably had the same blisters for about 18 years!!!

Joe Butler

darenius@aol.com

[Matt Cawthorne]

Sue,
I purchased a cd-36 (hull number 79, built in 1982) in January of 1993. At that time Sea Fever had approximately 30-50 very small blisters. My personality type would not allow me to just repair as you go. I Scraped all of the bottom paint off and opened up the blisters. None of my blisters had the purple ooze, more of a brown stuff that smelled like vinegar (acetic acid). I used a ball-ended wood rasp on the end of my drill for larger work and a dremel for the finer ones. On a few blisters when the obvious stuff was ground away a small brown stain would appear, so I ground away the material that the stain came from until there was no more brown stuff coming out. At this point you should wash the hull with fresh water every few weeks because any salt flushed out in the drying process will sit on the surface and will slow the drying process. I worried that the hull would not be dry enough, but tested it occasionally by sealing a sheet of plastic to the hull overnight with tape. If condensation is still collecting on the inside of the plastic you have a substantial way to go. DO NOT RUSH THIS PART OF THE PROCESS. When we were happy that the hull was dry we filled the holes (none were very deep or particularly wide) with West system epoxy and some of their filler compounds. We then washed the hull with a nasty solvent and sanded it with an orbital sander. The we wiped, tack ragged and washed it again with nasty solvent. We used the West system barrier coating which had 1 coat of clear epoxy and 5 coats mixed with a silvery additive. I wish I had put one extra coat with their copper compound. Each coat was rolled on with a roller and tipped off with a brush. You should not let the epoxy harden completely between coats or the amine blush will cause the later coats to adhere poorly. It should not feel tacky, but if you can see your fingerprint or a thumbnail dent it is time for another coat. If you let it harden completely you are in for anoter wash and a re-sanding before following coats. Interlux products are supposedly far more forgiving on re-coat times. When it was all done we washed with water, sanded again, washed with solvent, applied a no-sand primer, a marker coat of ablative bottom paint and two coats of the final color. Since then I have only had to touch up the paint when the marker coat shows up. The reason for going crazy with the prep for the paint is that I have seen many boats with bottom paint flaking and didn't want to get into the trap.
The result? Not one blister in four years.

There were some entertaining stories like finishing up coat number three at 10:00 pm on saturday night with the air temperature at around 40F. Thinking that it would take overnight with that low temperature to cure that coat we went to dinner. Upon returning at midnight we found that it was time for the next coat! The folks with the boat next to us did theirs about 3-4 weeks later and the higher temperatures allowed them to do the whole coating job in 1 day.
You have to do the job once for most of the hull, and then move the stands and do where the stands were.

Good luck, it was alot of work. Don't rush. It is worth doing the job correctly the first time. AND WEAR YOUR RESPIRATOR!

Matt



mcawthor@bellatlantic.net