Interior Crazing

**GordMay** · 24-05-2004, 03:44

CSY Man:

Interior crazing is generally of less concern than would be exterior cracks, which are much more likely to permit the entry of moisture., and further (developing) dammage. They (interior cracks) are also less common, as the interior gelcoat is usually under compression, rather than (the) tension (on the outside surface).

I hesitate to offer any opinion “sight unseen”; but with that caution suggest:

1. A thick (>25 - 30 mil), or over-catalyzed gelcoat surface, is susceptible to “shrinkage” cracking (akin to dried out clay)which often occurs (at the factory) during the initial cure (of the laminating resin) [see etiology 1, in original previous post]. The initial gelcoat stress was definitely spawned during the cure, and may have even cracked at the factory.

2. Directional changes (like corners) concentrate stress, so we’re not surprised that many stress-cracks occur there. Corners are (also) often places where structural attachments (bulkhead to hull) joints occur. Stress cracks (radial or convergent/divergent), at a corner or bulkhead-hull interface are suggestive of an angular restraint. No amount of simple crack sealing will prevent their reappearance. You must (somehow) relieve the stress. The simplest technique is to drill a small hole (about twice the diameter of the crack) at the ends of each major crack, prior to filling & sealing.

In short, I’d advise that you try to determine the underlying cause of the interior stress-cracks. They may very well be mostly cosmetic, or they may be symptomatic of larger structural issues. In any case, old as (I’m certain) they are, I don’t think they (likely) represent an urgent & immediate hazzard, unless they are “growing”.

Cosmetic repairs are tough! I’ve never been able to effect a perfect match (colour nor texture) on gelcoat repairs (even /w the factory-supplied kit that came /w my C&C). I have seen it done, by a highly talented artist - but even he prefers to paint over gelcoat repairs.

Regards,
Gord

CSY Man · 24-05-2004, 06:29

Good info, thanks Gord.

I will buy ya beer one day, ya just have to get yer butt down to Florida again

24-05-2004, 03:44	#1
GordMay Administrator Site Administrator Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 9,339 Images: 230	Interior Crazing CSY Man: Interior crazing is generally of less concern than would be exterior cracks, which are much more likely to permit the entry of moisture., and further (developing) dammage. They (interior cracks) are also less common, as the interior gelcoat is usually under compression, rather than (the) tension (on the outside surface). I hesitate to offer any opinion “sight unseen”; but with that caution suggest: 1. A thick (>25 - 30 mil), or over-catalyzed gelcoat surface, is susceptible to “shrinkage” cracking (akin to dried out clay)which often occurs (at the factory) during the initial cure (of the laminating resin) [see etiology 1, in original previous post]. The initial gelcoat stress was definitely spawned during the cure, and may have even cracked at the factory. 2. Directional changes (like corners) concentrate stress, so we’re not surprised that many stress-cracks occur there. Corners are (also) often places where structural attachments (bulkhead to hull) joints occur. Stress cracks (radial or convergent/divergent), at a corner or bulkhead-hull interface are suggestive of an angular restraint. No amount of simple crack sealing will prevent their reappearance. You must (somehow) relieve the stress. The simplest technique is to drill a small hole (about twice the diameter of the crack) at the ends of each major crack, prior to filling & sealing. In short, I’d advise that you try to determine the underlying cause of the interior stress-cracks. They may very well be mostly cosmetic, or they may be symptomatic of larger structural issues. In any case, old as (I’m certain) they are, I don’t think they (likely) represent an urgent & immediate hazzard, unless they are “growing”. Cosmetic repairs are tough! I’ve never been able to effect a perfect match (colour nor texture) on gelcoat repairs (even /w the factory-supplied kit that came /w my C&C). I have seen it done, by a highly talented artist - but even he prefers to paint over gelcoat repairs. Regards, Gord __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?"

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24-05-2004, 06:29	#2
CSY Man Registered User Join Date: Aug 2003 Location: Ft. Lauderdale Boat: CSY 33 Cutter, "Rhapsody" Posts: 1,744 Images: 45	Good info, thanks Gord. I will buy ya beer one day, ya just have to get yer butt down to Florida again