Hairline cracks in fiberglass deck

On a recent deluge, I noticed a drip from my cabin ceiling underneath my deck. I do have some small hairline cracks in my fiberglass topsides and need to coat it with something, though it is the high-humidity season in North Carolina and coatings don't typically like that.

I mostly don't know what the heck I am doing most days where marine coatings are concerned, but I need to address this quickly either with some epoxy mix or pretty thick touch up paint on my 30yo trawler.

Any experienced with this who can lend advice?

Thanks.

Close up pictures please...but hairlines don't normally leak....unless they go under a fitting and separated the sealant.


Often the water travels along seams, random routes a good distance and the entry point is hard to find.

psneeld said:

Close up pictures please...but hairlines don't normally leak....unless they go under a fitting and separated the sealant.


Often the water travels along seams, random routes a good distance and the entry point is hard to find.

Click to expand...

+1

psneeld said:

Close up pictures please...but hairlines don't normally leak....unless they go under a fitting and separated the sealant.


Often the water travels along seams, random routes a good distance and the entry point is hard to find.

Click to expand...

True that. I am tracing gravity so as my deck slopes upward near the bow, I can start with some fittings and or crack locations there.

But what I was asking about is a recommendation for any alternative sealant aside from my two part epoxy, which I think I will likely use...

Thanks,

I'm no expert, but I would be concerned that if the deck has a wood core, a simple external deck fix may not help. If the wood is/was saturated in water, it will be weakened badly and a fix to the deck will still leave a weak core beneath it.

Small hairline cracks in the gel coat popping up here and there over time are normal. I have a every year that get properly repaired. As Psneed indicates, they should not be deep enough to create leaks as you describe. Are your decks balsa core? I would check it out with a moisture meter.

Try this stuff as a BandAid, but sooner than later you need to properly remediate it. CAPTAIN TOLLEY'S Crack Cure Sealant, 2 OZ. | West Marine

caltexflanc said:

Try this stuff as a BandAid, but sooner than later you need to properly remediate it. CAPTAIN TOLLEY'S Crack Cure Sealant, 2 OZ. | West Marine

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Not only as a bandaid, but it can help you identify where the leak is coming from. Use it on one possible source of the leak and wait and see if the leak is gone. If it is, go back and do a proper repair. If it didn't stop the leak, go onto the next possible culprit.

More than likely leak is from a hatch or fitting.
Think of it this way, if you have a hairline crack in your bottom gelcoat does it leak into your bilge? Probably not.
Water leaks are a bitch to find, they travel from place to place, run down hill.
90% of time caused by bad bedding on a fitting or hatch.
If your topside cracks are that bad your core will be saturated and you have major problems. Doubt that is the case.
Pics would help.

I had to remove my complete cabin headliner and have someone on the bridge with a water hose fill the bridge deck. I stood below and found where the water was coming from. A huge undertaking I didn't enjoy! Hope you don't have to go to that extent but I had to. Those bridge deck leaks are like jungle gorilla warfare

Any deck that is cracked so much that it leaks needs to be replaced with a stronger deck.

There is no structural strength left if water drips through the laminate.

Hairline (of course depends on one's definition of what that is) cracks are usually an indication of something wrong with the core below. Regardless of whether they are causing water to leak into another space, they should be attended to; the implications will only get worse in time. The first step is to determine how deep they go. I can tell you from personal experience, a small crack over a void in the core can let a lot of water in. It could be that the core became wet, in turn causing the crack, by water entering from another spot such as a fastening spot.

You don't have to replace an entire deck, just the wet core area.

"Git Rot" is very thin epoxy. Good for dribbling into cracks.

"Gluvit" is good for large areas. It goes on like a paint.

I don't want to be a smart a##, but water doesn't always run downhill. If you are having trouble locating the entry point, you might look "uphill" of where the leak appears inside. This is due to surface friction. In construction using laminations or lap joints, it is possible for the materials to separate just enough to draw the water uphill at which point it is possible for the leak to show above the actual entry point. Just something to think about.

30yr. old Marine trader .... plywood core in decks.

I would suspect that it is coming in around your bow sprit or the scansion bases. But wherever it is, it is probably the same leak that softened your deck on the bow and it finally found its way into the cabin. Show it to me next weekend and let's see of we can find it.

I would be willing to take a look at the leak with you. I'm in the Wilmington area.
What you find at the source of the leak(s) will determine the best product and method for repair.

Shoot me a PM or give me a call, 949-939-6329.

Thanks, but boat's in New Bern now.

I've hit it with epoxy, the obvious spots. But I went crazy when I saw this surface on another boat:

Treadmaster Non Skid Deck Covering

This would remedy a host of issues. And my surface would look quite primo.

Anyone have experience with this?

Notlandlockedforlong said:

I don't want to be a smart a##, but water doesn't always run downhill. If you are having trouble locating the entry point, you might look "uphill" of where the leak appears inside. This is due to surface friction. In construction using laminations or lap joints, it is possible for the materials to separate just enough to draw the water uphill at which point it is possible for the leak to show above the actual entry point. Just something to think about.

Click to expand...

Completely ripping out the deck is my emotional thought. It passes quickly. But I think I am strategizing two-part epoxy to the visible spots, git-rot in any internal wet spots found, coating the deck, and then the rubberized mat surface in my prior post.

Just going to ruminate on it a bit before committing dollars.

Ben said:

Thanks, but boat's in New Bern now.

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Since not him, I would still get someone to look at it, perhaps someone at a boatyard, you pay just to look and advise. The thing is that you just don't know if your issues are surface, if it is in any way connected to the cracks, where it's most likely coming from. However, most importantly you don't know what damage is being done. This could be something that to fix now is relatively inexpensive (nothing is inexpensive, just not as bad as other), but if left unaddressed could end up major.

Having been in "the industry " and had to deal with the nemesis of cracks. Leaks can originate 10-20ft from where they drip.
Save yourself some agro and invest in a ultrasound generator/receiver. Body shops use them a lot to flood the inside of cars and check window seals /door seals.
I bought my last one from the U.K. on ebay, chased some window leaks down in no time on my trawler that weeped down the interior sealing and down the forward companionway steps.

I have found the Treadmaster Non Skid to be a bit rough on bare feet. If you're just doing a few areas and not the whole deck, maybe OK.

Martin J said:

Having been in "the industry " and had to deal with the nemesis of cracks. Leaks can originate 10-20ft from where they drip.
Save yourself some agro and invest in a ultrasound generator/receiver. Body shops use them a lot to flood the inside of cars and check window seals /door seals.
I bought my last one from the U.K. on ebay, chased some window leaks down in no time on my trawler that weeped down the interior sealing and down the forward companionway steps.

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Thank you very much. This sounds very much like what I need. You are correct. My deck is sloped up at the bow quite a bit, so I suspect it's coming from forward on back. I'll start nosing around on eBay, CL and Amazon if I have to.
Thanks Again!

After I just now checked - who makes these? Seems to be everything from checking gases to checking babies in bellies...

Don't forget that water can migrate upwards also due to capillary effects.

Ben said:

Treadmaster Non Skid Deck Covering
Anyone have experience with this?

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I have that stuff on my foredeck and afterdeck. It would be rough as-is, I'd recommend a deck coating to keep it soft to the feet. Also, you should consider coating it anyway because otherwise you are at risk of leaks around the edges and on the seams over time and weathering cycles.

I'm fixing small leaks/bubbles/cracks this summer, the material on my boat is many years old and coated. I'm using Rust-oleum Restore 2X coating. It is easy to work, tint-matched to existing, looks great, has good elasticity, builds up good without being too thick.

I'm sure there are those here with more expertise/experience with Treadmaster, but I find it reasonable stuff to walk on, maintain and repair.

Ben said:

Completely ripping out the deck is my emotional thought. It passes quickly. But I think I am strategizing two-part epoxy to the visible spots, git-rot in any internal wet spots found, coating the deck, and then the rubberized mat surface in my prior post.

Just going to ruminate on it a bit before committing dollars.

Click to expand...

Before I tackled all you are noting here, I would re-bed ALL your deck fittings. The bedding will fail over time and it is when you get a leak like you are noting that one of the buggers is leaking. It isn't as hard to do this as you might think and will give you years of a dry boat interior. If one is leaking, others will be soon behind that one.

Hairline cracks can be made waterproof with just a good wax if they are really just a hairline crack in the gelcoat.

Good luck!

S41 said:

Before I tackled all you are noting here, I would re-bed ALL your deck fittings. The bedding will fail over time and it is when you get a leak like you are noting that one of the buggers is leaking. It isn't as hard to do this as you might think and will give you years of a dry boat interior. If one is leaking, others will be soon behind that one.

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Ugh. Yes. I am avoiding that inevitability. Railings mostly. But cleats and stanchion, of course as well. Lots of exploration to get to the right spots in all. Good excuse for alcohol and power tools. (Joking. Sort of.)

Ben said:

Ugh. Yes. I am avoiding that inevitability. Railings mostly. But cleats and stanchion, of course as well. Lots of exploration to get to the right spots in all. Good excuse for alcohol and power tools. (Joking. Sort of.)

Click to expand...

When we purchased our Symbol 41 Sundeck last August, it had all sorts of leaks that took a bit to chase down. After a day of just searching, I just said 'screw it' and I lifted all the deck attachments (hand rail stanchions and a few cleats) and re-bedded everything. It only took an afternoon to get the job done. It was much faster than just trying to find what was leaking and where the water was coming from. I also re-bed around the forward deck hatch while at it. Dry boat ever since...

"It was much faster than just trying to find what was leaking and where the water was coming from. I also re-bed around the forward deck hatch while at it. Dry boat ever since..."

No goop lasts forever , re bedding is a PM style task, best done every few years , before your bunk is wet , before the PH windows fall out and before the deck rots.