spider cracks in gel coat.

[viago]

i am restoring a little 19ft sailing boat, having removed some of the grime, weed and barnacles i have found a lot of the gel coat has patches of tiny cracks in the gel coat resembling a spiders web.

does anyone here have any idea how i can quickly and easily fill these without having to first widen the cracks?

the hull is pretty sound but the problem is above deck.

i am reluctant to paint.

 

[vyv_cox]

I fear there is very little you can do about it. It happens because the GRP layup is far more flexible than the gelcoat. If the substrate flexes the gelcoat cannot comply and therefore cracks. Exacerbated if the original construction had gelcoat that was somewhat on the thick side. Much of my deck and cockpit is like it, painting or ignore it seem to be the only options.

 

[Swanrad2]

Saw a very good job done once on a Macwester - paint, sand aggressively, paint, sand aggressively, repeat until the cracks are filled. Lovely job, saw the boat again about 5 or 6 years later - still looked good.

 

[ghostlymoron]

They're possibly caused by a heavy impact. The accepted treatment is to enlarge each crack with a sharp chisel or Dremel tool and fill with gelcoat filler. Unless you are very skilled colour matching, they will probably be more obvious than they were before.

 

[viago]

what about captn tolleys with a white pigment added?

 

[Avocet]

what about captn tolleys with a white pigment added?

I don't think that ever really sets. Pretty certain you'll just end up with a crack filled with sticky mess. Are these cracks reasonably evenly distributed all over the surface, or are they localised in patches near some obvious load (like a chainplate, stanchion base, etc? If the former, they might not be impact damage. They could be some sort of ultraviolet attack on the gelcoat. Avocet suffered that. I was told to pressure wash as viciously as possible, then leave until a baking-hot summer day when the boat decks were bone-dry and after (say) 2PM when the temperature would start falling, then paint them with high-build epoxy primer in the hope that as the paint covered the surface and started to cool, the air inside the cracks would contract and help "wick" the primer down into the cracks, where it would set and hopefully, hold them together a bit better. That advice was on the assumption that I would paint afterwards, but I guess you could then sand it back, hopefully leaving the cracks filled. They'd still be visible though. I didn't go down that route in the end, so I don't know if it would work or not!

If they are definitely caused by a localised loading, you're pretty much doomed unless you can get to the back of the laminate under the cracks and reinforce it first, with a few layers of mat and resin. Otherwise, pretty much no matter what you do, they will re-appear. This is because having had a load applied that is big enough to cause the cracks in the first place, the structure is now weaker than it was, and therefore even less able to resist those forces than it was when new (and that clearly wasn't sufficient or they wouldn't be there in the first place)! If they are due to impact damage (say, a "berthing indiscretion", you might get away with it as long as you don't bash the boat in the same place again.

 

[Halo]

I suffered "a berthing indescression" when a clown rammed my berthing platform in Neptune Marina. The marina organised a free repair but fine cracks have re emerged on the horizontal areas which have a diamond tread pattern. I have shown the damage to three professional repairers and they have all declined to get involved. I have put 2 layers of Captain Tolleys on the cracks to prevent moisture getting in but after a couple of seasons this has gone a nasty colour.
Time has run out for a repair this season but my present thought is to sand the area flat and use a layer of sikaflex to bond on some Treadmaster ,cut to shape , when she comes out in the Autumn. This would serve to protect the laminate and should look OK
Anyone have a better idea?
Martin

 

[viago]

I don't think that ever really sets. Pretty certain you'll just end up with a crack filled with sticky mess. Are these cracks reasonably evenly distributed all over the surface, or are they localised in patches near some obvious load (like a chainplate, stanchion base, etc? If the former, they might not be impact damage. They could be some sort of ultraviolet attack on the gelcoat. Avocet suffered that. I was told to pressure wash as viciously as possible, then leave until a baking-hot summer day when the boat decks were bone-dry and after (say) 2PM when the temperature would start falling, then paint them with high-build epoxy primer in the hope that as the paint covered the surface and started to cool, the air inside the cracks would contract and help "wick" the primer down into the cracks, where it would set and hopefully, hold them together a bit better. That advice was on the assumption that I would paint afterwards, but I guess you could then sand it back, hopefully leaving the cracks filled. They'd still be visible though. I didn't go down that route in the end, so I don't know if it would work or not!

If they are definitely caused by a localised loading, you're pretty much doomed unless you can get to the back of the laminate under the cracks and reinforce it first, with a few layers of mat and resin. Otherwise, pretty much no matter what you do, they will re-appear. This is because having had a load applied that is big enough to cause the cracks in the first place, the structure is now weaker than it was, and therefore even less able to resist those forces than it was when new (and that clearly wasn't sufficient or they wouldn't be there in the first place)! If they are due to impact damage (say, a "berthing indiscretion", you might get away with it as long as you don't bash the boat in the same place again.

this might be the technique that swanrad saw on the macwester. i am not clear whether that boat was painted after of not.

the damage is in plenty of places but not specifically in load bearing places. probably age and swimming around the bottom of the ocean for a couple of years.
apart from the corners, which have the usual dents cracks and scuffs, the hull seems to have survived fairly well. the anchor points for the stays are all good, i think the mast has taken a bashing as the spreaders are bent but the foot area looks ok, still some debarnacleing to do there to be sure.

i can do a good paint job if need be but if i can do a few quick and easy repairs i would rather polish.

i thought tolleys did harden. probably worth the £12 anyway. i might try heating the areas with a gun and see what i can do with white epoxy.

 

[Avocet]

i thought tolleys did harden. probably worth the £12 anyway. i might try heating the areas with a gun and see what i can do with white epoxy.

Remember epoxy has famously lousy resistance to ultraviolet though. Many years ago, I had some white epoxy which I filled a few external holes with, but it went yellow very quickly.

 

[Avocet]

I suffered "a berthing indescression" when a clown rammed my berthing platform in Neptune Marina. The marina organised a free repair but fine cracks have re emerged on the horizontal areas which have a diamond tread pattern. I have shown the damage to three professional repairers and they have all declined to get involved. I have put 2 layers of Captain Tolleys on the cracks to prevent moisture getting in but after a couple of seasons this has gone a nasty colour.
Time has run out for a repair this season but my present thought is to sand the area flat and use a layer of sikaflex to bond on some Treadmaster ,cut to shape , when she comes out in the Autumn. This would serve to protect the laminate and should look OK
Anyone have a better idea?
Martin

I feel for you! They're never the same again. I think your idea could work, but you need to be careful that the raised "tread blocks" are just pure gelcoat and that the laminate doesn't try to come up the middle of them. If it does, then when you grind them off, you'll expose the glass fibres (which could then do with being sealed before you put the Treadmaster on). I think an appropriate grade of Sikaflex should do that well enough. Can't think of a better idea! Star cracks do often carry on growing for a month or more after the initial accident - which is very annoying!

 

[viago]

i spoke to a very well respected fiberglass repair guy at the yard today, he said that the only effective tretment is to draw a circle about a cm wide of the affected area and grind out the gell coat down to the glass. apparently the cracks can sometimes spread into the glass and if left they will extend.
he then re-glasses to near the surface level and then fills with fresh gell coat.
the problem is colour matching, of which is is an expert, i have failed to see the holes he has repaired in other boats.
i might give it a go, not that fussed about colour matching, white will do. however, i'll ask for a price for him to colour match me a litre of flocoat.

 

[nigelmercier]

See this recent thread: http://www.ybw.com/forums/showthread.php?390121

 

[vyv_cox]

the problem is colour matching, of which is is an expert, i have failed to see the holes he has repaired in other boats.
i might give it a go, not that fussed about colour matching, white will do. however, i'll ask for a price for him to colour match me a litre of flocoat.

I worked as a colour matcher many years ago. It is very difficult to achieve a good match even using a meter, which I doubt that many boatyard repair people have. I had a repair made to my gelcoat at Palma Boatyard, Mallorca, who are probably one of the world's top yards, dealing with superyachts every day of the week. I watched him do it and agreed with his methods. Even there the repair was visible when complete but it has weathered in over the years.

 

[viago]

I worked as a colour matcher many years ago. It is very difficult to achieve a good match even using a meter, which I doubt that many boatyard repair people have. I had a repair made to my gelcoat at Palma Boatyard, Mallorca, who are probably one of the world's top yards, dealing with superyachts every day of the week. I watched him do it and agreed with his methods. Even there the repair was visible when complete but it has weathered in over the years.

i dont doubt what you say but there is a fairly new fast fisher next to me on which this meterless guy repaired a 4"hole in the hull and i will offer you 100 to 1 that you can not find the repair.

my project is an old 19ft sailing boat of unknown vintage which is worth less than the cost of restoration so, a few colour tones out wont bother me too much. colour matching is a mystery to me, wouldn't know where to start.

 

[fisherman]

I have impact repairs to my hull, the gel was shattered, cracks have not come through. Thick hull though. I have just repaired some spider cracks from impact damage, epoxy filler with colour pigment, I will over coat with Perfection 2 pack paint.

 

[vyv_cox]

i dont doubt what you say but there is a fairly new fast fisher next to me on which this meterless guy repaired a 4"hole in the hull and i will offer you 100 to 1 that you can not find the repair.

I don't doubt it. It all depends on the pigments available, as there is no such thing as a pure colour, e.g. reds will contain some blue or yellow, plus they will darken. Blacks will always have some red/green and blue/yellow. If your man is repairing a white that is not too bright and he has the right pigments that he is familiar with he will no doubt do a great job.

 

[viago]

I have impact repairs to my hull, the gel was shattered, cracks have not come through. Thick hull though. I have just repaired some spider cracks from impact damage, epoxy filler with colour pigment, I will over coat with Perfection 2 pack paint.

did you grind out the damaged area or just deepen the cracks and fill?

 

[fisherman]

did you grind out the damaged area or just deepen the cracks and fill?

I ground back as far as needed to find uncracked substrate, in all cases the GRP/mat was intact. Most spider cracks I ground deeper and wider individually, enough so the filler made a good wide fillet

 

[handsome-transom]

New product in Trailerboat Fisherman

Hey, there's a product that was in the Trailerboat Fisherman mag that is for hairline cracks in gelcoat that is getting really good reviews... but I'd be interested to see if anyone has used it yet and what they fixed with it..... if it is as easy as they say, could be a bit of a winner for fixing that sort of stuff. I'm keen to try some so if no one posts back, I'll try and take some pics to put on here if I get some.