Crazed gelcoat with greenish colouring?

[Pepijn]

Hello,

I am currently looking at a boat to purchase. After haul out today we found what appears to be crazed gelcoat underneath the antifouling. I have attached some pictures.

1. Is this a big issue? Can it be solved with a barrier epoxy?
2. What could be the greenish "stuff" in the cracks?

[Tetepare]

Algae

[Greatest Lakes]

Looks to just be algae. Best bet would be to have the bottom soda blasted, touch up any rough areas, barrier coat and bottom paint.

[Pepijn]

Thanks for the answers!
We will discuss today whether to go ahaead with the purchase or not.

[Boatyarddog]

Originally Posted by Pepijn

Hello,

I am currently looking at a boat to purchase. After haul out today we found what appears to be crazed gelcoat underneath the antifouling. I have attached some pictures.

1. Is this a big issue? Can it be solved with a barrier epoxy?
2. What could be the greenish "stuff" in the cracks?

The green is Antifouling. Copper exposed to air, and salt.
Crazing, should be explored, for wet areas in the glass.
Barrier coat, will seal it out, but be sure to dry the glass if it shows moisture in the glass.
Otherwise your sealing in water.
Really need to explore the entire hull if you see crazing like this.
Strip the bottom paint off, and inspect the gelcoat.
If the gelcoat is not showing this all over you can spot repair, but I'd probably barrier coat the whole thing after opening any wet areas and drying it well.
Then barrier and bottom paint.
Boatyarddog

[Don C L]

What I see doesn't look concerning based on my experience. My 60 year old boat has plenty of crazed gelcoat. I have found no evidence of it causing any damage to the fiberglass. I might be concerned if the crazing was around chainplates though. But, what boat are we talking about here? Many European boats have very good reputations for the quality of their build and fiberglass work.
In my own case, I removed any loose gelcoat and filled with white marine tex in deck areas. But I have places at/under waterline where gelcoat was crazed and chips came off and previous owner just painted over it and it is fine. If there is not a blistering problem (and it looks like there are none) and water is not infiltrating the glass, or osmosis, I bet you could just bottom paint it and go sailing. One advantage to sealing the crazing though is that algae won't get in there and make the waterline look kinda ugly after a while.

[Scubaseas]

Originally Posted by Boatyarddog

The green is Antifouling. Copper exposed to air, and salt.
Crazing, should be explored, for wet areas in the glass.
Barrier coat, will seal it out, but be sure to dry the glass if it shows moisture in the glass.
Otherwise your sealing in water.
Really need to explore the entire hull if you see crazing like this.
Strip the bottom paint off, and inspect the gelcoat.
If the gelcoat is not showing this all over you can spot repair, but I'd probably barrier coat the whole thing after opening any wet areas and drying it well.
Then barrier and bottom paint.
Boatyarddog

This is excellent advice

[Rumrace]

It’s the antifowling paints past best before date. Green copper sulphate. Came in the paint and apparently safe as milk.

[Boatyarddog]

Originally Posted by Don C L

What I see doesn't look concerning based on my experience. My 60 year old boat has plenty of crazed gelcoat. I have found no evidence of it causing any damage to the fiberglass. I might be concerned if the crazing was around chainplates though. But, what boat are we talking about here? Many European boats have very good reputations for the quality of their build and fiberglass work.
In my own case, I removed any loose gelcoat and filled with white marine tex in deck areas. But I have places at/under waterline where gelcoat was crazed and chips came off and previous owner just painted over it and it is fine. If there is not a blistering problem (and it looks like there are none) and water is not infiltrating the glass, or osmosis, I bet you could just bottom paint it and go sailing. One advantage to sealing the crazing though is that algae won't get in there and make the waterline look kinda ugly after a while.

If you chip off gelcoat, your very likely to actually see glass fibers sticking out of it.
These exposed fibers is what causes osmotic water ingress into glass, it can then break down resin and other process can begin.
If you used Marine Tex to repair gelcoat, you basically used epoxy over that area.
That's exactly what Barrier coat is, and does exactly what it says, a Barrier, to water ingress caused by open fibers of glass exposed to water.

Gelcoat is generally poly resin sprayed before glass is laid into the mold and acts as a barrier to water ingress, as well a mold release.
Crazing caused By a lot of things, weak old gelcoat, strikes may be local, flexing, of the hull in stressed under protected areas, and generally is not serious.
However, UNDER the waterline should be resealed.
Boatyarddog

[Rumrace]

I would pass on a boat with cracked gel coat top or bottom. Cracks along the sanction mounts spell rotten laminate and cracked bottom the water has all ready migrated and washed out structure.
Hammer it for spongy spots find a long thin one run away. Any spongy glass around sanctions pass.
The deal is the expensive one well loved.
Fibreglass has a limited life span and it’s not water proof at all with out a gel coat.

[Don C L]

Originally Posted by Boatyarddog

If you chip off gelcoat, your very likely to actually see glass fibers sticking out of it.
These exposed fibers is what causes osmotic water ingress into glass, it can then break down resin and other process can begin.
If you used Marine Tex to repair gelcoat, you basically used epoxy over that area.
That's exactly what Barrier coat is, and does exactly what it says, a Barrier, to water ingress caused by open fibers of glass exposed to water.

Gelcoat is generally poly resin sprayed before glass is laid into the mold and acts as a barrier to water ingress, as well a mold release.
Crazing caused By a lot of things, weak old gelcoat, strikes may be local, flexing, of the hull in stressed under protected areas, and generally is not serious.
However, UNDER the waterline should be resealed.
Boatyarddog

Not arguing with you, but in my own case I have found no soft or spongy glass and no blisters yet. There was a good deal of hand laid-up roving used in my boat and if they used any mat (that would show exposed fibers) I haven't seen it yet. I believe my boat was also built before the chopper gun too. I have a friend whose boat does suffer from blisters and there was a considerable amount of mat used in the construction, though I believe the more likely culprit is the resin used at the time.

[Pepijn]

Morning all!
Very interesting feedback! Much appreciated.
The boat is a Moody 425 from 1990, which I believe are well and strongly built.

After the haul out we did not find any soft spots. Once the sale can be concluded we will strip to gelcoat, have it very well dried out, inspect, and apply barrier coat.

[Boatyarddog]

Originally Posted by Don C L

Not arguing with you, but in my own case I have found no soft or spongy glass and no blisters yet. There was a good deal of hand laid-up roving used in my boat and if they used any mat (that would show exposed fibers) I haven't seen it yet. I believe my boat was also built before the chopper gun too. I have a friend whose boat does suffer from blisters and there was a considerable amount of mat used in the construction, though I believe the more likely culprit is the resin used at the time.

Being a pre 70 s boat, yours was probably laid by hand.
Most quality builds were, top sides used chopper guns, mainly.

Newer production boats started the decline in hull builds in my opinion.
Likely you have a strong hull.
Boatyarddog

[Don C L]

Originally Posted by Boatyarddog

Being a pre 70 s boat, yours was probably laid by hand.
Most quality builds were, top sides used chopper guns, mainly.

Newer production boats started the decline in hull builds in my opinion.
Likely you have a strong hull.
Boatyarddog

Yeah it was laid up with tight weave roving and fairly thick, (no oil canning) and the deck has 1/4" ply with 1/8" of the roving on either side. One of the reasons I love the little old boat.

[Boatyarddog]

Originally Posted by Don C L

Yeah it was laid up with tight weave roving and fairly thick, (no oil canning) and the deck has 1/4" ply with 1/8" of the roving on either side. One of the reasons I love the little old boat.

Yes, my old Coronado 28 was a Columbia, B. Crelock build 74/75, nice sailing Sloop. 2500lbs Ballast on a 6800lbs boat, made it pretty stable, and 8.5' beam, I usually loaded it heavy, down low.
All lead keel.
That boat balanced really well, once set, you could ride at the bow and it steered itself forever without touching the wheel.
https://sailboatdata.com/sailboat/coronado-28

Nothing like the Ketch I sail now!
Like the difference between a Cadillac and a Honda.
Boatyarddog