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Old 24-09-2020, 12:29   #1
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Hairline crack?

Iíve been noticing these little cracks on the deck, maybe theyíve always been there and i never noticed or maybe theyíre new? I feel like I would have noticed them before. I bought the boat in June, so its new to me. Is this considered a hairline crack? Should they be tended to when we haul out for the winter or is it simply cosmetic? Iíve seen other posts on the topic, but none had any pictures of the cracks in question. Any insight would be greatly appreciated!
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Old 24-09-2020, 13:05   #2
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Re: Hairline crack?

Thin, like hair? Cracks, like irregular shapes? Yup, hairline cracks.


Captain Tolley's - https://www.westmarine.com/buy/capta...ealant--243990


Other cure is to gouge it out and rebuild and repaint the non-skid, much harder.


Good luck.
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Old 24-09-2020, 13:22   #3
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Re: Hairline crack?

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Originally Posted by Stu Jackson View Post
Thin, like hair? Cracks, like irregular shapes? Yup, hairline cracks.


Captain Tolley's - https://www.westmarine.com/buy/capta...ealant--243990


Other cure is to gouge it out and rebuild and repaint the non-skid, much harder.


Good luck.


Haha...It does check off all those boxes. Thanks for the product suggestion!
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Old 25-09-2020, 03:21   #4
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Re: Hairline crack?

Apparently a common problem? Maybe some of the video clip here are worthwhile?

https://www.google.com/search?source...sclient=psy-ab
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Old 25-09-2020, 05:24   #5
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Re: Hairline crack?

Hmmm. Something caused the crack, or a crack, to keep it hypothetical. Assume that that hypothetical crack is structural, such that you want to stop it, not just keep it from leaking. The West Marine stuff fills it, but does not add any strength, or prevent propogation of the crack, which grew to it's present size and can keep growing. That's a separate problem from filling it to keep water from leaking though it.

Cracks grow because the microscopic ends of the crack are whopping concentrations of stress. That end point can take, say, the force from your stepping on the deck at that point and concentrate into a tiny space. The way you reduce that stress, such that it doesn't propogate, is to stop drill it. You take a drill bit many times the size of the endpoint of the crack, but still pretty small (1/8" or less) and drill out the very end of the crack carefully. That spreads the force and stops the propagation. Fill and move on.

The ports in my boat came with curved corners (in the steel). I cut them to sharp corners because square windows are easier to fabricate than radiuses. But, I welded angle iron patch behind every corner, because a corner concentrates stress the same way as a crack, only less so. They found out about this phenomenon when Liberty ships started cracking at their square hatches.

Good luck with it all.
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Old 25-09-2020, 06:52   #6
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Re: Hairline crack?

This will most likely be due to the flexing of the deck and cracking/breaking the gel coat. Seldom are cracks like this ever a problem but you would want to investigate. You will see these stress cracks on old boats often over hatches, close to cleats, etc..

The way to repair it is to reinforce/stiffen the area. Ground out the crack, glass and re-gel coat. That would be particularly difficult on yours due to the textured non-skid that you will never get looking like factory again, without making moulds and replacing it.
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Old 25-09-2020, 13:03   #7
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Re: Hairline crack?

Iíve worked in a lot of oem shops...including OíDay. The hairline cracks can occur when pulling the part out of the mold, tightening stuff, trying to pull parts into alignment, lifting the boat, overcranking the rig, hitting bottom, storms, fat crew, manatee attack...who knows because they can be the result of any number of stresses. Some are structurally meaningless..wash them out with acetone and fill with superglue or captain thuds thin epoxy. Get a big bubba to step, not jump, on and off the area while you look at a straight edge with a good light...then look belowdecks. Needle a little acetone into the crack. See it or smell it on a clean cloth rubbed underneath? Is it going into a core? Tap round it like surveyors do. Is there a moving stress...example, cranking up the backstay.
Or does it open enough to weep or does the deck move when you heel hard over...what Iím trying to get you to see is that the cause can still exist or the crack was a one time event. The cause can be 10 feet from the crack. I think itís a waste of time to start reinforcing before you know whatís going on. But with some boats, the weakness is well known and can be eliminated quickly.
Drilling stop holes at the end of aluminum cracks sort of works till you can weld.
A small drill stop hole...not into the core...might also help but itís not a permanent solution. Freeze thaw cycle can split open wet rock so itís good you are taking a look at the cracks. You can use an air compressor and leak soap...forgot about that. Iíd ask the Plexus guys if they have some thin products. Too much acetone exposure. My face has hairline cracks but Iím not worried my keel will fall off.
Happy trails to you
Mark and his pizza and beer loving manatees
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Old 25-09-2020, 13:10   #8
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Re: Hairline crack?

Quote:
Originally Posted by althea82 View Post
I’ve been noticing these little cracks on the deck, maybe they’ve always been there and i never noticed or maybe they’re new? I feel like I would have noticed them before. I bought the boat in June, so its new to me. Is this considered a hairline crack? Should they be tended to when we haul out for the winter or is it simply cosmetic? I’ve seen other posts on the topic, but none had any pictures of the cracks in question. Any insight would be greatly appreciated!
It's pretty normal. Just gel coat crazing. Can be caused by too hot a mix/shrinkage, or just the boat flexing. gel coat is very brittle. I've done the same thing, saw some and wondered why I didn't notice before.
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Old 25-09-2020, 13:48   #9
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Re: Hairline crack?

Hi. I forgot SV Jedi had some terrific posts on fixing Gelcoat and primers and painting...we are aluminum so itís different.
Not sure where his old posts are, but someone here can help.
Lastly, keeping manatees off your sugar scoop is simply a matter of sufficient beer and a quality carbon filter mask.
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Old 25-09-2020, 13:56   #10
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Re: Hairline crack?

I'm a little concerned about the cracks by the cockpit drain. If your cockpit is cored with anything, could be plywood, balsa, who knows?, but you do need to find out if it is wet under that series of cracks. Just my opinion. Gelcoat cracks that stay in the gelcoat aren't so very bad, but if they're letting water go wandering under the skin, not so good....but fixable, and eventually you'll learn something about color matching.

Ann
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Old 25-09-2020, 15:01   #11
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Re: Hairline crack?

Quote:
Originally Posted by Manateeman View Post
Iíve worked in a lot of oem shops...including OíDay. The hairline cracks can occur when pulling the part out of the mold, tightening stuff, trying to pull parts into alignment, lifting the boat, overcranking the rig, hitting bottom, storms, fat crew, manatee attack...who knows because they can be the result of any number of stresses. Some are structurally meaningless..wash them out with acetone and fill with superglue or captain thuds thin epoxy. Get a big bubba to step, not jump, on and off the area while you look at a straight edge with a good light...then look belowdecks. Needle a little acetone into the crack. See it or smell it on a clean cloth rubbed underneath? Is it going into a core? Tap round it like surveyors do. Is there a moving stress...example, cranking up the backstay.

Or does it open enough to weep or does the deck move when you heel hard over...what Iím trying to get you to see is that the cause can still exist or the crack was a one time event. The cause can be 10 feet from the crack. I think itís a waste of time to start reinforcing before you know whatís going on. But with some boats, the weakness is well known and can be eliminated quickly.

Drilling stop holes at the end of aluminum cracks sort of works till you can weld.

A small drill stop hole...not into the core...might also help but itís not a permanent solution. Freeze thaw cycle can split open wet rock so itís good you are taking a look at the cracks. You can use an air compressor and leak soap...forgot about that. Iíd ask the Plexus guys if they have some thin products. Too much acetone exposure. My face has hairline cracks but Iím not worried my keel will fall off.

Happy trails to you

Mark and his pizza and beer loving manatees


The previous owner was a rather large man, to say the least and is probably the reason the pulpit and a good deal of the stations are bent. The all seem to be in high traffic areas, or places where you would step down (with exception of the crack by the handrail). Iím no feather weight, but I donít think I have enough force to crack the gel coat?

If it was a result of a stress (outside of a large old man thumping around) would the gelcoat inside the cabin also be cracking?
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Old 25-09-2020, 15:23   #12
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Re: Hairline crack?

Quote:
Originally Posted by Manateeman View Post
Hi. I forgot SV Jedi had some terrific posts on fixing Gelcoat and primers and painting...we are aluminum so itís different.
Not sure where his old posts are, but someone here can help.
Lastly, keeping manatees off your sugar scoop is simply a matter of sufficient beer and a quality carbon filter mask.
Captain Mark and his offgassing manatee friends
In this case, with just a crack in otherwise good looking gelcoat, I would take a Dremel with 1/8Ē diameter steel grinding bit (I prefer round, ball shaped) and grind down the crack over the full length. This will show if it continues into the laminate or not. Probably not. After that, fill the crack with a thickened epoxy. You can use West System and after mixing with hardener, add some cabosil (colloidal silica) until it is ketchup consistency. Put that in a ziplock, cut a little corner off and use it to fill the crack like chefs decorate cakes with whip cream. I buy the disposable bags they use.

Thereís more you can do: paint it. If you donít paint, the epoxy will deteriorate. I cheat by mixing some white pigment into the epoxy, hoping it will stay good until I get to paint it, plus it blends in with the white deck.
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Old 25-09-2020, 15:29   #13
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Re: Hairline crack?

Quote:
Originally Posted by althea82 View Post
..........
...................................


If it was a result of a stress (outside of a large old man thumping around) would the gelcoat inside the cabin also be cracking?



Not necessarily, depends on how it's built. My boat has outside fiberglass, then wood, then an inside separate fiberglass liner. Those cracks wouldn't show up inside.
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