ebb
agree 5/16th for the thinnest locations.
i"ve seen a significant variance in thickness around the hull.
1/2" to 3/4" for the thru hulls
bottom of keel was approx 1.5" inch
leading edge of keel up to 1.5" glass with up to 2" polyester resin behind that.
thin spots for A-231 are keel void aft (since beefed up).
Hey Ken,
Great idea on the styrofoam.
For those pour in place junkies why not line the hole in the bilge with wax paper? Maybe tape in some construction cardboard first to smallify the hole a bit, then the wax paper,
so the foam will come out easier.
That's a great concept for those who need lost sock convenience in the form of a BILGE PLUG. Right-on!!!
Making the plug slightly smaller might allow covering it with 6oz fiberglass so it won't get dented and waterlogged.
Last edited by ebb; 07-03-2009 at 05:58 AM.
Bill,
I put a transducer (more like a golf club than a hockey puck) in the stem a while ago, and that may confirm your observation on hull thickness. BUT
Believe I found the stem on A338 just "turned the corner" and wasn't any thicker then the hull. However after recovering from disbelief, I really beefed up the length of the stem with many turns of tabbing, Xmatt and hairy filler.
And now I wish I had laminated extra fabric onto the OUTSIDE of the whole keel/ballast keel/bilge area as I assume you did before the barrier coat process.
Drilled a number of holes into the encapsulated ballast void for discovery and for draining water and filling with epoxy. Even down here the hull was no thicker than 5/16", maybe 3/8", on the sides. My first drain holes (from the Manual) were straight up through the bottom of the keel where there was considerable thickness (one inch maybe?) But any glass LAYERING was rather abrupt, because side drain holes low down were thru much thinner hull.
__________________________________________________ __________________________________________________ ____
This has been a discussion of discovery. An important revelation we've all been involved in. Fantastic.
I'm unaware freezing stress IN THE HULL LAMINATE has been mentioned as a cause of gelcoat crazing by the mavens of info that abound the internet.
This observation may be unique. It's not mentioned in any list of gelcoat crazing causes. It's important because it may signal compromised fiberglass.
Bill has identified an important issue for owners of older fiberglass boats.
It seems laminate freezing would be especially important problem for our not very beefy hulls. I think we're talking about plastic within the laminate cracking into small pieces by freezing. Or worse. If bilge water weeps through the hull in crazed gecoat areas then this HAS to be a conclusion!
Here the Forum really informed to perfection!
{be nice if ebb wasn't so damn long winded.}
Last edited by ebb; 06-11-2009 at 11:30 AM.
I decided to see how far up the crazed gelcoat went. I started sanding a path up from the keel and the crazing goes all the way up to the top of the barrier coat and then stops dead in it's tracks at the waterline stripe. At first I thought it was maybe associated with the dark color of the bottom paint but that cannot be it since the black waterline stripe does not have any problem under it.
So what in a barrier coat would cause the crazing?????
Interesting to say the least!
Long spider lines has to mean that whatever caused the cracks was stress over the whole surface. That it STOPS at the waterline it has to have something to do with the boat being in the water.
It might have been something like the boat being in the water an extended time and then pulled out of the water to dry for a long time. Gelcoat can be thought of as somewhat porous and if - let's say - it is 'full' of water, and that water leaves suddenly there could be some shrinkage to the gelcoat that might explain what you discovered. Those long crazing lines show that the stress occurred over the whole underwater surface, which at the moment you might assume until all the below the waterline gelcoat is revealed.
Thinking of the gelcoat layer as so many millimeters thick: If the shrinkage is in the 'top' mm(s) of the gelcoat and not all the way thru to the laminate then it is a cosmetic problem not a structural one. There may be ofcourse some deeper cracks BUT NO SEPARATION from the substrate.
It has been said that proto crazing has been in the gelcoat from the time the boat was made. In other words the crazing over time opens up due to whatever stresses are put on the surface. The gelcoat is by nature a thick non-fibrous coating. Can't remember the source for the above sentance - but if it is correct that the gelcoat upon leaving the mold already has charted fault lines, then the topsides would have them also, they haven't been separated- yet.
Some suggestions:
The cause may not be all that important, if the solution is relatively straight forward. Imco you are gonna have to remove the bottom paint down to the gelcoat. There are some nearly user friendly chemical strippers that are comparatively easy but messy to use, the kind you paint on, cover with film, let sit, and scrape off. But dustless.
Take a section now of what you have discovered ands shown us in the photo and forensically sand a small section of the gelcoat down over a crack(s). Hopefully the crack will disappear as you go deeper. You want to find that there is no evidence of the specific crack going thru TO the fiberglass and absolutely NO crack IN the fiberglass. I think that is what you will find.
You want to confirm that the gelcoat altho cracked is firmly attached to the laminate.
After the bottom paints have been removed, then 40/60 grit sand the white gelcoat, not to remove, then stabilized as suggested above. Then barrier coat.
imco
Last edited by ebb; 06-15-2009 at 05:58 AM.
The plastic classic website when someone else asked the same question and these are the responses he got back.
http://plasticclassicforum.com/viewt...7&hilit=spider
Just did a quick scan of the thread. Usual stuff, no revelations imco - interesting it's a Pearson boat.
Believe I've read that the Ensign is the most active keel boat fleet in the world(?)
Could be old age (brittle) gelcoat......
But that is not the cause. Like they say, it's a symptom.
Disagree that you can just let it go. But depends on your relationship with the boat and your circumstances. We know there is an issue with moisture (water vapor at least) in the laminate. If you have the opportunity, why not, do what we know is good for the ole girl. If the boat is hauled regularly maybe a barrier coat is unnecessary.
No one talks about the crazing getting worse. But of course nobody looks very often UNDER their bottom paint at the gelcoat. Better to protect the boat and everybody agrees 'barrier coating' is an upgrade.
But something CAUSED the phenomenon.
Nobody really knows what.
A number of things could be making the crazing more severe.
My opinion is to try to do something about it.
I think stabilizing the gelcoat is the way to go.
I'm convinced that keeping water out of the laminate is the best thing an owner can do to extend the life of these boats built in the '60s.
The clincher would be that if somebody chimed in and said.
"Oh, I had that problem 10 years ago, and I stripped her and barrier coated.
Haven't had a problem since. No more crazing.
Dry as a bone.
And, you know, the boat seems a lot lighter than it used to!"
Last edited by ebb; 07-03-2009 at 06:08 AM.
A 259 has the same problem, below the waterline gelcoat is crazed and deep crevices throughout. Above the waterline , the gelcoat appears smooth and undamaged.
View the photos in the A 259 thread.
I assumed I had a unique problem but evidently not. Well maybe it is the constant soaking and then the drying out when hauled or just the nature of bottom paints ingredients.
I don't plan on sanding off all the gelcoat, just smoothing it up, fairing he voids, sealing and painting. Hopefully someone will tell me , yeah, that's good enough.
Some of the gelcoat appears to be 1/8-3/16" thick.
This is what I know so far.
First the only place I had a blister problem was in the area where the gel coat had been destroyed by previous bottom jobs. And the blisters were not in the gelcoat because there was no gelcoat for them to be in. They were in the barrier coat when I sanded through that they were gone.
I believe they were caused by the trapped water in the foam inside the keel.
From what I have read fiberglass is more like wood then I previously realized. It takes on water and gives it off just like wood over it's entire lifetime. Does not matter how many coats of finish you put on wood it will still take on and give off moisture on a regular basis.
With fiberglass it is not good to seal both sides of the material and trap whatever water that is currently in it there. That can cause blisters.
So....
This is the direction I'm leaning towards in dealing with my situation.
First in the area where the previous boat yard folks blew through the gelcoat I think I should follow Bill's example and lay a layer of 6oz. cloth over that area and then fair it out. Then after any other things that need work are done (such as the keel damage done by the previous owner) I will barrier coat the entire hull below the waterline. And finally apply bottom paint.
Second I need to finish removing the foam inside the keel and leave that area open to breath so that moisture can go in and out without causing damage.
I meant to reply to Ebb.
Carl it seems this type of thing is far more common then I would have guessed.
I don't want to get caught up in definitions here, but what I viewing on your keel is not blisters. My understanding of blisters is water leaching into the laminates and being trapped. When they are "popped" they have an order of uncured fiberglass.
I think your problem is as you described over zealous sand blasting creating leaches and allowing water to flow into the keel and be trapped and then leak out when the boat is hauled. The quick fix someone threw at it failed mainly because the hull wasn't dried on the inside.
Your plan for repair as Bill231 described is I think correct and forever your problem in this area is solved. IMHO
Good Luck, Carl
Could be a reaction to either strippers or paint itself, Saw it happen on a fiberglass hood once. Painter said it was from having too much solvent in the primer.
Just the shape and directions of the crazing makes me think it's NOT stress or impact.
Ken.
I would refer to it as surface crazing. My Commander has a lot of this kind of crazing in the cockpit area. The gelcoat is almost a 1/4-3/8th inch. I have ground out some area's for repair and found that it is confined to the gelcoat and responds well to grinding and filling.
Regarding the hull below the waterline, I haven't seen that kind of crazing, but I am still resisting total removal of the 1/8 in. layer of old bottom paint. It is removing itself in stages. Some every year. I will overcome.
John / WA1JG
John G.
Valhalla
Commander No 287
Imco it is perfectly OK to seal BOTH SIDES of the hull.
If it is 'breathing' you are worried about - the hull laminate will breathe no matter what you do.
If the breathing is water transfer thru the laminate then sealing both sides is the only way to go!
There is NO proof I'm aware of that prohibits sealing off the hull from water as best you can. I'd like to read the source.
You should seal when the hull is relatively dry. Dry inside and out, No bloody foam. You might never have a bone dry hull hull. So you put your barriers on when the boat has been out of the water as long as you have time for. There are epoxies that can be applied under water. Most require a dry SURFACE. There will always be some moisture/water vapor in the laminate no matter what you do.
A properly prepared hull surface - a premium 100% solids no blush epoxy - and there will be no blisters or any action from the old polyester. BUT the argument for keeping water out of the laminate is to SEAL THE INSIDE OF THE HULL and the outside.
Rubber barrier maybe?
Taking the old paint down to the glass inside is crazy. You would do it because new bulkheads and tabbing and so forth needs a grinded clean surface.
If sealing the bilge, grinding with 36 or 50 grit and fairing by sanding is the way to go. Loose paint, gunge, old punky glass removed. Really impossible to remove the old paint. If sound it must be neutral by now!
Then paint on 3 coats of Ultra-Tuff. Probably the easiest to use, no pot life, out of the can, waterborne, no solvent urethane rubber coating on the market. Prep is everything.
DUSTLESS Hull strippers.
You certainly can find peel-and-strip environmental strippers for the bottom paint that will have NO effect on the gel coat. In fact some of these strippers will not strip epoxy primers and barrier coat already on the hull.
While the peel-and-strip might be touted as environmentally friendly (in quotes), the resulting mess can hardly be.
When I did it, I had heavy plastic film under the boat, I don't know how many gallons of thick paste on the multi layers of copper bottom paint, the paper-backed film over that. It made a large sodden pile of UNenvironmental toxic waste that thank the landfill gods was disappeared into a convenient dumpster at the yard. Not pretty.
But caustic damage to gelcoat by paint strippers is a thing of the past. You can still find those methylene chloride ones if you insist. Please don't
Last edited by ebb; 07-03-2009 at 06:31 AM.
Drilled 3 holes in the keel void area today. Just a smidge of water oozed out - tablespoon-ish. Put the blow-end of my shop vac in the top hole and got airflow out of both of the lower holes. A little nugget of foam popped out too that was bone dry. Knocking doesn't sound like there is much more void space below the bottom hole. Might give it a go and drill below it just to see. Definitely empty space in there, but not full of any water to speak of. No harm in letting it air out for 6 months.
(water on the substrate below the keel is from manually pumping out a little leftover water in the bilge)
Kyle
C-65 Lucky Dawg
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