I have an 83 Cape Dory Typhoon that I am restoring. It has unusual gel coat cracking in certain areas of the deck. So far I haven't found anybody who knows what caused them. The deck core seems to be dry, no dead spots in hammer testing and no typical stress cracks in the area. The boat spent the last 7 years on it's trailer, under a tarp. I need to know the cause before I attempt to fix them. Thanks in advance!
Unusual cracking in Typhoon deck, what is the cause?
- Thread starter Coppertone
- Start date
without a close inspection, it may be tough to be sure. It looks like freeze and thaw cycles have taken their turn at this. Standing water on fiberglass, doing the same thing will often look like this. Is this the low spot on the side decks? Does it extend beyond where water would collect?
It appears to extend in to the nonslip and the cracking also follows the stain pattern.
More pics or known boat history may help. You could find a spot, less prominent and dremel or cut one or two to see what is behind or between them and the layup.
It appears to extend in to the nonslip and the cracking also follows the stain pattern.
More pics or known boat history may help. You could find a spot, less prominent and dremel or cut one or two to see what is behind or between them and the layup.
The cracks do extend upward onto the wall of the cabin a bit. In one spot they also occur on the wall of the cabin right before it returns to the companionway. See the additional pics.
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That would be my SWAG.
Moisture getting into the gelcoat or under the gel coat then freezing could easily create such cracks in the thing surface. Once started it would be relatively easy to continue over several seasons. The fact that it goes up the side a bit could also be explained by wicking of the moisture perhaps with some snow on the deck, then a freezing cycle.
It is not a definitive answer. You are going to be doing some removal, assessing that you have a sound sub-strata, then sealing the exposed substrata, and resurfacing of the affected areas.
I concur with @shemandr I would be inclined to see if the bits chip off. It would expose the lack of attachment to the substrata that makes up the deck. If deck is plywood you might have a substrata that you can work with. If not (say it is end grain balsa) then it may be deteriorated and you will need to replace the core before repairing the surface.
Thankfully it is winter and such projects can help to pass the time till sailing season returns to Ohio.
It looks like paint to me, cold be paint and the next surface . Sand some and see if the surface is damaged under this.Cause 7 years, heat cold under a tarp.
I've seen that before on old boats. It looks like thermal cycling cause cracks in gel coat that was applied in a coat that was too thick using a formulation of gel coat that was too brittle.
The fix is to sand off all the old gelcoat down to glass laminate, prime and fair the surface with epoxy primer, refinish with topcoat paint.
It's a huge, dirty job.
The fix is to sand off all the old gelcoat down to glass laminate, prime and fair the surface with epoxy primer, refinish with topcoat paint.
It's a huge, dirty job.
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Judy, you may be right. I just went out and popped a chip of the gelcoat loose. It came off (relatively) easily with no real adhesion to the underlying layup. That said, the area immediately adjoining that was quite tight to the laminate. I guess this is a topside equivalent to an osmotic blister?
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Older boats were way over built as designers and builders didn‘t understand fiberglass like they do today. The laminates were very thick and the gelcoat was thick. Because of the excess thickness of the laminate there are many older hulls still as strong as the day they came from the factory. I suspect there are multiple causes of your problem. The gelcoat is not as flexible as the underlayment, especially if it was sprayed into the mold too thick, so over the years tiny cracks have taken their toll. Gelcoat is not waterproof so with many years of exposure to wet/dry and freeze/thaw conditions it is degraded. Were it me I would sand, fill and paint with a two part epoxy paint. Actually, if it really were me I wouldn’t do anything because it’s only cosmetic and I would go sailing and have a good cigar.
That last picture is nasty. That isn't just gel coat, it's the laminate that is deteriorating. Likely due to poor resin mixing and/or exposure to moisture and freeze/thaw cycles. How much do you have invested in this project? I'm sure this is repairable but will likely require stripping the entire deck and cabin down to the glass mat or even down to the core and re-glassing over it.
I am pretty sure that the appearance of the mat in that photo is because the PO pressure washed the boat and forced dirty water down into that small delaminated area. The crack I opened to pop off that chip was the biggest and most open, that's why I chose that spot. After trying to raise more of the gelcoat I found the other areas were much better bonded. I'm going to dremel some more of those cracks and seen if I encounter more delams.
I know of more than one old boat with similar, randomly oriented, widely distributed cracks in the gelcoat . The owner sailed it for years “as is” before she sold it . The subsequent owner sanded down the gelcoat to remove all the loose chips, and then faired the deck with epoxy high built primer. Then he applied the topcoat.
I think it was a mid 1970’s model, one of the very first produced in the boat’s lengthy production run.
I think it was a mid 1970’s model, one of the very first produced in the boat’s lengthy production run.
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We owned a Cape Dory in the late 80's through 90's. It was 10 to 20 years old at that period, and had many of the same cracks in the gel coat. I think Judy is right, CD's gel coat was extra thick and that just happened (I've head this from other CD experts as well).
I wouldn't worry too much about it except to know you could sand and fill the worst ones and go on to painting the boat.
Hard to believe but next year, 1980 sailboats will be 40 years old! You guys with 80's boats, your boats are old!!! When did that happen?
For years I've seen many that have spent days compounding and waxing old chalky gelcoat hulls only to end up in denial,... and still with old chalky gelcoat hulls.
Take age in stride: It can be liberating to paint aged out gel coat that has long ago given up the ghost. You can now paint your way to a new boat. Do a lot of work and get many years out of it - or do a sufficient amount of work and get several years.
Your choice. But you can have the newest looking 80's fiberglass boat in the yard, as often as you want, for less work than you think.
My fiberglass hull will by 59 years old next season.
It's time to paint the topsides again. I do it every 3 - 4years with one part. My daughter and I rolled and tipped the 38' topsides 3 seasons ago in about 5 hours (I did about 6 hours prep prior to this). I could spend more time and $$ for a longer finish but with my sloppy docking and general abuse, this fits the bill for us.
We'd like to see a 'new' Typhoon posted here, next spring.
I wouldn't worry too much about it except to know you could sand and fill the worst ones and go on to painting the boat.
Hard to believe but next year, 1980 sailboats will be 40 years old! You guys with 80's boats, your boats are old!!! When did that happen?
For years I've seen many that have spent days compounding and waxing old chalky gelcoat hulls only to end up in denial,... and still with old chalky gelcoat hulls.
Take age in stride: It can be liberating to paint aged out gel coat that has long ago given up the ghost. You can now paint your way to a new boat. Do a lot of work and get many years out of it - or do a sufficient amount of work and get several years.
Your choice. But you can have the newest looking 80's fiberglass boat in the yard, as often as you want, for less work than you think.
My fiberglass hull will by 59 years old next season.
It's time to paint the topsides again. I do it every 3 - 4years with one part. My daughter and I rolled and tipped the 38' topsides 3 seasons ago in about 5 hours (I did about 6 hours prep prior to this). I could spend more time and $$ for a longer finish but with my sloppy docking and general abuse, this fits the bill for us.
We'd like to see a 'new' Typhoon posted here, next spring.
Thanks to everyone who took the time to respond. It is beginning to look like I'll dremel all of the cracks down to the layup, chip out any gelcoat that will come loose, repair those areas with epoxy, then redo the decks with awlgrip. I was already planning to refinish the decks anyway. TomY I agree with what you said about having to paint old gelcoat, especially on decks because they take such a beating. I don't know that I'll have this boat done by spring because I have an unheated workshop, so epoxy and paint season is rapidly coming to a close, but I hope she's done by mid-summer. Again, thanks everybody!
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So I contacted Andy Miller from Boatworks Today to get his thoughts. He says that the random cracking is due to the outer surface of the chopped strand mat hull layup being a bit starved of resin when it was laid up. The dry mat fibers trigger cracks above the strands, hence the pattern seen. I will have to remove the gelcoat in those areas, sand the surface of the layup, then fill in the void with a few layers of new chopped strand mat. The area involved is only about three feet long on either side of the cabin, and a few spots on the cabin itself. It should be a pretty manageable job. I was planning on repainting the decks anyway because there are a few stress cracks to repair, so it's a bummer, but not terrible.
Not really that unusual for a Cape Dory. They often laid the gelcoat on too thick, and the layup was hand-rolled resulting in some dry spots/fibers. The result, over time, can be what you are seeing or severe crazing.