Sanding 10 Years of Bottom Paint!

This is the place to post your ideas, thoughts, questions and comments as relates to general boatbuilding and reconstruction techniques and procedures (i.e. recoring, epoxy, fiberglass, wood, etc.)
Post Reply
User avatar
TritonSailor
Rough Carpentry Apprentice
Posts: 66
Joined: Tue Jan 06, 2009 6:10 am
Boat Name: S/V Alcyone
Boat Type: 1960 Pearson Triton Hull #194
Location: Middletown, CT
Contact:

Sanding 10 Years of Bottom Paint!

Post by TritonSailor »

Hello Everyone,

I'm in the middle of sanding and grinding my way through 10 years of bottom paint. As I uncover the gelcoat, I am noticing that it is crazed and in some areas there are for a better word small holes that expose the epoxy coating. As I got used to the process, I might have dug in in places to the lower epoxy coat as well. Should I apply a fairing compound to fill in the craze, holes and digs? Maybe then follow up with Interprotect 2000 as a barrier coat. Thanks in advance for the advice.

Jeff
Jeff
1960 Pearson Triton #194
User avatar
Rachel
Master of the Arcane
Posts: 3044
Joined: Tue Dec 07, 2004 7:59 pm

Re: Sanding 10 Years of Bottom Paint!

Post by Rachel »

I understand the gelcoat crazing, but what do you mean when you say going through to the epoxy? Do you mean the whitish fiberglass/mat layer beneath the gelcoat? Or the greyish resin? (which would most likely be polyester) Or an epoxy coating?

Here is a photo of the bottom of my A-30 when I was grinding it out in preparation of filling a through-hull hole; it gives you an idea of what it typically looks like inside. In my case:

Red bottom paint
grey Interlux 2000
White gelcoat
Mat
Resin
Woven roving
plus more mat, more resin, more woven roving, etc.
Thickened epoxy that I'd put in the hole (new) is the cream-colored circle in the center

Image

Do you have any photos of what you're finding?

Rachel
User avatar
TritonSailor
Rough Carpentry Apprentice
Posts: 66
Joined: Tue Jan 06, 2009 6:10 am
Boat Name: S/V Alcyone
Boat Type: 1960 Pearson Triton Hull #194
Location: Middletown, CT
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by TritonSailor »

I'm going back out for more torture today so I'll get a few pictures. It's the epoxy coating right under the gelcoat. It's a dark gray color. I have been lucky enough not to go down to the fiberglass at this point so I'm hoping my errors can be fixed easily.
Jeff
1960 Pearson Triton #194
User avatar
Rachel
Master of the Arcane
Posts: 3044
Joined: Tue Dec 07, 2004 7:59 pm

Re: Sanding 10 Years of Bottom Paint!

Post by Rachel »

Okay. If it's under the gelcoat on a Triton, I would suspect it's the beginning of the polyester resin. Unless something really weird has been done, there wouldn't be an epoxy coating/layer under the gelcoat (but they are sometimes added over the gelcoat as you can see on mine (white gelcoat, then dark-grey epoxy coating).

Photos will help us to see what you're seeing.

Rachel
Duncan
Candidate for Boat-Obsession Medal
Posts: 388
Joined: Fri Mar 03, 2006 7:28 am
Boat Name: Coquine
Boat Type: Cape Dory 27
Location: Montréal
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by Duncan »

TritonSailor wrote:It's the epoxy coating right under the gelcoat. It's a dark gray color.
From what you say ("right under the gelcoat"), I doubt that's epoxy. It's far more likely to be a secondary layer of polyester gelcoat. I believe that it's differently-coloured so that you can tell where you're at.

When I did this a few years ago, I ground/sanded until I felt I'd reached a solid surface. Then I filled and faired with thickened epoxy.
Image
Cape Dory 10 & 27
User avatar
TritonSailor
Rough Carpentry Apprentice
Posts: 66
Joined: Tue Jan 06, 2009 6:10 am
Boat Name: S/V Alcyone
Boat Type: 1960 Pearson Triton Hull #194
Location: Middletown, CT
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by TritonSailor »

Here are pictures of what I uncovered as I sanded the bottom:
Image

Image

This is a little blurry, but its where I went in too deep. I think I will need to fair it with epoxy before the barrier coat.
Image

Thanks

Jeff
Jeff
1960 Pearson Triton #194
Duncan
Candidate for Boat-Obsession Medal
Posts: 388
Joined: Fri Mar 03, 2006 7:28 am
Boat Name: Coquine
Boat Type: Cape Dory 27
Location: Montréal
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by Duncan »

I think you're ok.

Here's a similar sequence:

Flaking bottom paint along the waterline:
Image

(White) gelcoat beneath (with a second layer of darker, medium-blue gelcoat showing in the middle of the holes):
Image

(Darker, medium-blue) second layer of gelcoat in the centre. You can maybe see (if you squint) untinted yellow fiberglass of the hull, right in the centre of the darker second layer of gelcoat :
Image

So, I know for sure that, on this boat (Paceship), there was a darker layer of medium-blue gelcoat inside the white gelcoat on the outside. Not all boats were laid up this way, so you will have to eyeball your own situation. When you get to yellow stuff, though, that will be the (resin and glass) hull.

In my case, I ground off the gelcoat for about a foot along the waterline, where the pinholes were.
(There were still some small pinholes into the second later of darker gelcoat, and into the yellow glass, but these were not very deep).
I laid on two or three layers of pure epoxy resin, then two layers of slightly thickened resin (for fairing).
You'll want to prime on top of the expoxy, since bottom paint won't stick to it.

From what I hear, this is a pretty normal phenomenon on older boats. Polyester gelcoat isn't completely waterproof, and for some reason, this shows up most as these pinholes along the waterline. (I think that's also what you see in the white layer at the 10-11 o'clock position on Rachel's photo, too).

Not to worry, if that's as bad as it got in 30-40 years, a bit of grinding and a few layers of epoxy is easy and buys you lots more time.
Image
Cape Dory 10 & 27
User avatar
Tim
Shipwright Extraordinaire
Posts: 5708
Joined: Tue Apr 01, 2003 6:39 pm
Boat Name: Glissando
Boat Type: Pearson Triton
Location: Whitefield, ME
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by Tim »

Jeff,

That's just the beginning of the laminate right beneath the gelcoat. Pearsons of this vintage often had a very dark gray/black layer right under the gelcoat, between the roving/mat and the gelcoat; I am not sure what this layer is, exactly, but it's on most of these old Pearsons As you sand, you tend to run into this on both hull and deck. You can see many instances of this dark color layer showing through if you wade through restoration pictures of Tritons and similar-age Pearsons on the various sites available online. If you were to sand further, you'd soon uncover the laminate itself, which is a lighter brownish-green in color. I see some of it it on your last photo, in the center of the sanded area.

Obviously be careful as you sand/grind and avoid going deeper than you have to. Fill and fair as required when all is said and done. Remove any loose gelcoat; you'll find that most of the surface is going to be covered with cracking and crazing of various severity. It it holds up to sanding, you can leave it alone unless you want to spend the next 2 years fussing over your bottom. If sanding seems to chip/flake it off, then sand enough only to find sound material.

Relax and keep going.

I'd advise against barrier coat: I think it's a waste. You can search this forum for past threads where I have discussed my reasoning in some detail and form your own conclusions from there.
---------------------------------------------------
Forum Founder--No Longer Participating
User avatar
TritonSailor
Rough Carpentry Apprentice
Posts: 66
Joined: Tue Jan 06, 2009 6:10 am
Boat Name: S/V Alcyone
Boat Type: 1960 Pearson Triton Hull #194
Location: Middletown, CT
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by TritonSailor »

Thank You Tim, Rachel, and Duncan for your insights. Tim, I don't see that the gelcoat is flaking or chipping away in those areas, so that is a relief. The day after my first post on this topic I watched someone putting the Interprotect on and looked at the advantages and decided to go with it. I will alternate gray and white to ensure coverage. I just feel that with all the cracks in the gelcoat, it's just asking for moisture to seep in and cause more problems. So I'm going to nip it in the bud now.

Thanks everyone

Jeff
Jeff
1960 Pearson Triton #194
Figment
Damned Because It's All Connected
Posts: 2845
Joined: Tue Apr 08, 2003 9:32 am
Boat Name: Triton
Boat Type: Grand Banks 42
Location: L.I. Sound

Re: Sanding 10 Years of Bottom Paint!

Post by Figment »

Tim wrote: unless you want to spend the next 2 years fussing over your bottom... .
What're you trying to say?
Hirilondë
Master of the Arcane
Posts: 1317
Joined: Thu Dec 28, 2006 8:50 am
Boat Name: Hirilondë
Boat Type: 1967 Pearson Renegade
Location: Charlestown, RI

Re: Sanding 10 Years of Bottom Paint!

Post by Hirilondë »

When I restored my boat I had some serious resources at my disposal. My boss, wanting to get rid of partial cans of paints offered me any and all paints I could find in any of the yard paint cabinets. Well, I found enough Interprotect to do 4 coats on my bottom. Boy did I feel fortunate.

Much later on in the project I was doing some serious cleaning up. I had installed a drain plug, so flooding the interior was no issue. While I was rinsing out the bilge and keel cavity I noticed (how observant of me) that the interior of the hull down there was bare glass/resin. Seeing as there is always some water down there, if only from cleaning, how much help can sealing the other side be? Consider also that my boat was 39 years old, and in spite of needing some serious attention cosmetically, the hull was in great shape aside from the cosmetics and a little physical damage. So 39 seasons of saturation did little if any harm. Factor in also, that even if you tried to seal both sides could you really succeed in preventing moisture from reaching the glass/resin?

You have to do what makes you feel comfortable, or you can't enjoy your boat. Just keep in mind that paint manufacturers like to make money. The more products and related needs, even if the needs be supposed, the more they make. Their motivation isn't necessarily in your best interest. You do want to create a surface that bottom paint will adhere well to however. And that may include applying something. But I think that sealing a bottom from moisture is an illusion.
Dave Finnegan
builder of Spindrift 9N #521 'Wingë'
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
Gresham’s Law of information: Bad information drives out good. No matter how long ago a correction for a particular error may have appeared in print or online, it never seems to catch up with the ever-widening distribution of the error.
User avatar
Tim
Shipwright Extraordinaire
Posts: 5708
Joined: Tue Apr 01, 2003 6:39 pm
Boat Name: Glissando
Boat Type: Pearson Triton
Location: Whitefield, ME
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by Tim »

An Interlux manufacturer's rep visited me a year or two ago and just from the way he asked "so, are you doing barrier coats" it was abundantly clear to me just what a cash cow this product is. All what was missing was the little wink-nudge-wink to go along with his connotation.

The Chicken Little blister hype works out well for the paint manufacturer, but also (especially) for yards, which usually vastly overcharge for what is a brainless application job for the lowest grunts in the heirarchy. Yards love to get customers to buy into the hype behind the whole sensationalistic blister/barrier coat confusion.

You already have the stuff, so go for it. But be aware that it is not some miracle cure (especially when a problem doesn't even exist), and that most likely it will just have no particular effect one way or another--not positive, not negative.
---------------------------------------------------
Forum Founder--No Longer Participating
User avatar
Rachel
Master of the Arcane
Posts: 3044
Joined: Tue Dec 07, 2004 7:59 pm

Re: Sanding 10 Years of Bottom Paint!

Post by Rachel »

Duncan wrote:From what I hear, this is a pretty normal phenomenon on older boats. Polyester gelcoat isn't completely waterproof, and for some reason, this shows up most as these pinholes along the waterline. (I think that's also what you see in the white layer at the 10-11 o'clock position on Rachel's photo, too).
Not that it really matters, but there weren't any pinholes in the gelcoat in the photograph I posted (didn't find any anywhere on the boat, actually; perhaps due to its having lived in a place with short seasons, and very dry winters (hauled out).

I agree about the fact that polyester gelcoat is water permeable though, in general.

Rachel
User avatar
Rachel
Master of the Arcane
Posts: 3044
Joined: Tue Dec 07, 2004 7:59 pm

Re: Sanding 10 Years of Bottom Paint!

Post by Rachel »

I hope it's okay to post/ask this, but I'm interested in what folks here think about the hydrolysis idea in older boats. I'll post a link to an article that talks about it (which is written by a boatyard). I thought the idea sounded plausible but I have no way to know for sure.

Here's the link:

http://www.zahnisers.com/repair/blister/blister1.htm

Basically what they are saying is that blisters are caused by water penetrating the gelcoat and reacting with certain parts of the resin in the laminate to make a new fluid (the brown smelly stuff that is inside blisters). Apparently the new fluid has larger molecules and so it cannot pass out through some (newer) gelcoats. So it makes blisters.

They go on to say that older gelcoat is more permeable, so the same process occurs, only the "new" fluid can make its way back out through the more-permeable gelcoat, so blisters do not occur. But, they (and others) contend that this process of parts of the resin basically "washing out" of the boat can eventually weaken the hull, as a result of the starved laminate that results.

They do say that no-one should worry about their hull melting away - that only a few of the older, "non-blistering" boats will actually experience enough deterioration (in the near future) to be a problem; so they're not screaming "Sinking sinking!" or anything like that.

With the wealth of knowledge and experience on this board, I wonder what people think about this? It sounds plausible to me, over the long haul, but that's just me reading and thinking about it.

If it were true, I could see a case being made for either barrier coat, or time spent "airing" the boat each season (which many people do already in colder climes).

Again, I'm not posing this in favor of barrier coat, or to say the sky is falling; more just to bring it up as a question.

Rachel
bcooke
Master of the Arcane
Posts: 2272
Joined: Sat Oct 04, 2003 10:55 pm
Boat Name: Jenny
Boat Type: 1966 Pearson Triton
Location: Rowley, MA
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by bcooke »

Unless anyone here has done the laboratory testing then disputing the article would be sort of pointless wouldn't it? I am also pretty sure this has been the prevailing theory for quite some time among people that actually know what they are talking about.
If it were true, I could see a case being made for either barrier coat, or time spent "airing" the boat each season (which many people do already in colder climes).
Are we reading the same article? The article essentially states that the whole 'airing' process is a fallacy. The moisture levels might go down but the impurities and damage remain and the process will resume as soon as the boat hits the water again. They also state that a barrier coat is really only useful on new boats and in any case the benefits only last 2-5 years.

The article also states that no one has done the testing to see how significantly the laminates actually degrade. Now THAT would be an interesting read. Finding out how long these boats are expected to last would be nice to know.

Maybe in 20 years I will just peal the hull below the waterline, add a few layers of resin and fiber to the outside (carbon fiber should be cheap by then) and go for another 70 years.
-Britton
Work is overrated.

Most everything you read on the Internet is wrong.

The Website
The Blog
User avatar
Tim
Shipwright Extraordinaire
Posts: 5708
Joined: Tue Apr 01, 2003 6:39 pm
Boat Name: Glissando
Boat Type: Pearson Triton
Location: Whitefield, ME
Contact:

Re: Sanding 10 Years of Bottom Paint!

Post by Tim »

When I hear the documented and legitimate story of the first boat to literally fall apart and just sink like a pile of Kleenex because of hydrolysis, blisters, or any of the minor, semi-related issues, then perhaps I'll start to become legitimately concerned. Not to suggest that I have my head in the sand, but honestly, at least where I am, it's such a non-issue as to be just not worth worrying about. I know there are instances of real blisters that occur, normally in tropical waters. Fair enough. But even then, the scope and severity of the problem, in an overall sense, must be kept in the proper perspective.

I think there is probably a yet-to-be-determined realistic lifespan for a fiberglass boat. No one knows yet; I sure don't, but I am realistic enough to anticipate that any old thing is probably going to require one or more major revamps to continue its lifespan. This holds true for cars, houses, boats, buildings, bridges, whatever you like. Every man-made product has a practical lifespan, and while some things can last a long time, everything requires maintenance and upkeep to stem the natural aging process. Even natural formations like mountains disappear, given enough time.

But even this theoretical lifespan assumes that no one takes any measures to shore the boat up in the meantime. It may be as simple as peeling and relaminating a couple outer layers of material, even if the "worst" happens as some of these articles like to opine. This has already become a routine procedure, and while it is invasive and expensive, it certainly does not signal the end for any boat. It's expensive to maintain and repair a wooden or steel boat too. Or maybe all of this is unsubstantiated theory that will never come to pass in any boat that has had a modicum of decent maintenance throughout its life. Time will ultimately tell.

Clearly even the people who write these articles don't really know, but that doesn't seem to stop them from raising unfounded concerns based on some theory that they have. I sure don't know, but I haven't seen anything that makes me worry desperately about it either. All I am suggesting is that one consider carefully both sides, and don't jump off the cliff in despair based on articles that, when probed beneath the surface, really don't offer any real information. Even laboratory testing has its limitations; how often have we seen that in the real world? Nature will always win. Meantime, soldier on and worry only when it's really time to worry. Good maintenance in any structure always has the effect of prolonging its lifespan, so provide good maintenance to your boat.

I believe that structures beginning to fail purely from the mechanisms of age always show warning signs with ample time. In a fiberglass boat, this will likely manifest itself in the form of cracking showing the working and stresses of the boat in places where it has not previously been working/moving. There is legitimate science in the chemical reactoin that occurs within a fiberglass laminate when exposed to salt water; I am not suggesting otherwise. I am, however, suggesting that in the overall sense this probably isn't the end of the world that some would like us to believe. Should this process continue long enough, I suppose someday we will start to see structural failures. This assumes ignorance of warning signs and a lack of attending to those signs, however. So pay attention and look for these signs while maintaining your boat.

We have seen old wooden boats revitalized with major surgery that often includes replacement of all or most of the major structural components. Steel boats require significant ongoing maintenance, and still deteriorate slowly, eventually requiring plate repairs and other repairs. It's not realistic to expect that fiberglass is suddenly the only product that won't require any maintenance and will last indefinitely. Obviously that is not true. Water is the universal solvent, and given enough time and neglect, it surely will eat up a boat. Any boat. So to make a fiberglass boat last indefinitely, the likelihood is high that certain important repair measures may one day be required. I doubt any coating is going to prevent this need, or even delay it, frankly.

Barrier coats haven't been around long enough for anyone to know whether they do what they are advertised to do over the long haul; in fact, information suggests that they fall substantially short of expectations and, in some documented cases, have even created moisture/blister-related issues where none existed before application of the miracle cure. In any event, they were conceived initially as gelcoat replacement products, for use in cases where the gelcoat was removed for major repair processes. like some of the legitimate severe blister problems that have been documented in the past. In this sort of application, they have their place, in my opinion.

My skepticism on barrier coating comes from their now-widespread use as some form of "preventative" maintenance that is a good idea "just because". I am far from convinced of that.

I think we should prove the theories before worrying about the potential results. A local weatherman, when discussing potential snowfall in the long-term forecast, often quips, "we don't shovel potential". From this, I extrapolate the statement that boats don't fall apart on theory either.
---------------------------------------------------
Forum Founder--No Longer Participating
User avatar
Rachel
Master of the Arcane
Posts: 3044
Joined: Tue Dec 07, 2004 7:59 pm

Re: Sanding 10 Years of Bottom Paint!

Post by Rachel »

Thanks for your thoughts on that. I like the mountain and wooden boat analogies. So true! I wonder if Bruce Pfund has done any testing of the nature that would give any insight? He does some interesting experiments/testing/detective work.

Britton, I should clarify what I meant by "airing" as I can see I didn't explain what I meant very well. I wasn't referring to drying out a blistered boat, but just to giving any fiberglass boat a bit of time each year out of the water, to let the fiberglass have some time to ... well.. not be in the water but instead in the nice dry air. Not to cure a visible problem, but just to help prolong the overall life of the laminate (if it does, indeed, do so).

Rachel
meubcr
Bottom Paint Application Technician
Posts: 23
Joined: Thu Jun 26, 2008 10:31 pm
Location: Austin, TX

Re: Sanding 10 Years of Bottom Paint!

Post by meubcr »

Blistering/hydrolysis aside, I have applied Interlux 2000E to the entire boat as a high build primer, as well as to enjoy any protection benefits. 7 gallons and 2 days of sanding later, I loved the end result. I got an absolutely smooth surface that was beautifully faired and completely devoid of pin holes and any other blemish. Given what I started with, the outcome was amazing. All in, this effort cost nearly $1,250 + time. A tip: Have the gallon cans of pigment shaken at your local Home Depot/Loews before starting so as to stir up all the solids in the bottom of the can.
Post Reply