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Catalina 25 Specific Forum

What do you do about cracking in deck gelcoat?

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Initially Posted - 10/17/2012 : 18:07:10

I have some cracks in the deck of my 1987 year boat. I'm concerned about water penetrating the wood core, and so thinking about filling them in with Marine Tex. What do you guys do about cracks like these?

Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2 (sold - yay!)
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
https://whichsailboat.com/2014/07/27/catalina-25-review/

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Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 10/17/2012 : 19:48:10

The first question is if these are "spider cracks" where the gelcoat shrinks from age and parts, or whether they're true stress cracks in the underlying fiberglass.

The former is quite common on older boats... The cracks are very fine, and you can't push a small wire even 1/8" into them. The fiberglass is generally fine, and wood core under it safe. You can buy gelcoat patch in a tube, squeeze it into the cracks, let it set, and sand it smooth with a very fine grit. Sometimes it helps to open them a little with a knife point before filling.

Stress cracks are another matter, and raise the question of why they are there. Marine Tex can be part of the solution or the whole solution--it depends on the nature of the crack. If this appears to be more than spider cracks, it would help for us to see some photos and know where they're located.

Edited by - Stinkpotter on 10/17/2012 19:53:51

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 10/18/2012 : 06:33:36

As Dave said, but gelcoat is brittle and some fine crack patterns are also flex related but insignificant. Fiberglass is flexible and many fine patterns in gelcoat will will just reappear after repair with no underlying problems.

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 10/18/2012 : 07:48:39

They seem to be larger than the spider cracks. The smallest ones are at the base of the mast and middle of the cockpit floor. Some larger ones are in the cockpit where the bench seat meets the bulkhead, and some are on the cockpit coamings near where they meet the bulkhead, and some are were the gunwale has a break in it to let water drain off the side decks. I'll take some photos next time I'm down at the boat and post back.

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NautiC25
Admiral

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USA
957 Posts

Response Posted - 10/18/2012 : 10:46:51

I also have one on the cockpit floor near the companionway. The area around it is slightly raised, and the fracture is fairly wide. Definitely not a spider crack, nor is it from the weight of standing on it.

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Stu Jackson C34
Admiral

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844 Posts

Response Posted - 10/24/2012 : 11:37:42

Small cracks: Captain Tolley's Creeping Crack Cure

Medium cracks: Marine Tex would work, but it isn't going to look anything like gelcoat after a year or two. Consider using the methods outlined in the Catalina owners manuals and dig out some of the crack and re-gelcoat.

Larger cracks: could be structural or could be dealt with like medium ones.

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 04/08/2013 : 14:16:05

I just took some photos of the cracks at the base of the mast. What do you guys think? Also, is the mast sinking into the deck?

http://www.flickr.com/photos/81052370@N03/sets/72157633199807990/

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awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 04/08/2013 : 14:37:10

That looks like the core under your mast step may be compromised. If you pour water does it puddle in the depression? The mast step should be the highest thing around and the water should all spill off.

The area around the mast wiring also looks potentially compromised.

Have you tried doing the tap test around there to check for delamination?

These are the kind of very shallow gelcoat-only cracks that the Daves were talking about:
http://www.flickr.com/photos/11038160@N02/1030611746/

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 04/08/2013 : 17:30:55

Thanks awetmore.

I've been doing overdue maintenance the boat since buying it 3 years ago, and I'm not sure how repairing the deck around the mast step should be prioritized. This summer I planned to fix the outboard that stalls after it warms up, fix the cracked rudder, build new hatch boards, refinish the brightwork, and replace the cracked deck house fan vent.

The mast has been sunken like this for the 3 years I've had the boat and despite the apparent greater depression on the starboard side of the mast, the starboard shrouds have just as much tension as the port side. This makes me thing the mast has stopped sinking, for now. With that in mind, should I move rebuilding the mast step to my number 1 priority, or can it wait if I seal up the cracks in the gelcoat?

Is it possible the compression of the deck was caused by over-tightening the rig?

Edited by - on

awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 04/08/2013 : 18:20:29

I'm going to say up front that I'm not an expert on core issues, I've just read about them a lot and have inspected two boats with similar mast step issues.

I don't think that over tightening the rig is very likely to do it. What is your upper shroud tension?

Are the bolts that hold the deck step visible from inside the boat? Is there any signs of water (brown drip stains) there? Tapping around to check for delamination seems like the other test.

I have no personal experience with fixing these sorts of things, just checking them when inspecting boats. It's not fatal and it is a fairly common thing to fix. If water in the core is the culprit then I'd want to figure that out sooner rather than later so that the delamination doesn't spread. The plywood core used by Catalina is stronger than balsa, but spreads moisture more easily.

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ftworthsailor
Captain

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USA
279 Posts

Response Posted - 04/08/2013 : 18:54:08

"Are the bolts that hold the deck step visible from inside the boat?
"
I have a 1978 C-25 and I just replaced the mast step and added a Halyard accessory plate. Mine required 4 stainless looking lag bolts that screw into the wood post inside. The wood looked good and dry so I sealed it with 5200 and bolted it back in. I was told that on some later models, you can see that they have a nut and bolt system. Here is a picture of mine after the installation:

I havent started working on my C-25 yet, however here are pictures of the repair we did to my C-22 cabin. Check out the corners...
<b>BEFORE PICS:</b>

<b>AFTER PICS:</b>

Looks pretty good ! ! !

Edited by - ftworthsailor on 04/24/2013 11:28:04

sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 04/21/2013 : 14:18:16

Thanks for the replies.

The shroud tension is about 25% less than what is recommended in the rig tuning page on this forum.

I have not yet been back to the boat to see if water is leaking in under there, but the bolts are visible in the head.

Water will definitely pool in this depressed area around the mast step, so I expected it is leaking in.

I've read a lot of posts on here about fixing soft spots in the deck. It seems that this case is different because the deck has compressed under the mast. Should I try to get at the rotted and compressed wood under the fiberglass? It seems like I would have to cut an area of the fiberglass away at this point.

Instead of cutting away at the deck, what about injecting epoxy and rot stopper under the compressed area, and then filling it in and leveling it with Marine Tex? If there's delamination extending further out away from the mast, I could use one of the other methods described elsewhere on this forum for that area.

Edited by - sethp001 on 04/21/2013 15:01:33

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