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Catalina/Capri 25/250 Sailor's Forums

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C-25 Deck core repair

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sailingchefs
1st Mate

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USA
28 Posts

Initially Posted - 04/06/2010 : 08:27:56

Spring has sprung in NH! Time to start stirring epoxy...

I've searched the archives, and didn't turn up any references to the type of repair I'm making. I had my boat surveyed last fall, and the surveyor found an area of delaminated core around one of the lifeline stanchions on the port side of the coachtop.
He said that the C-25 deck was cored with plywood, so there was no need to cut open the deck to replace the damaged core. Just drill small holes an inch or two apart down to, but not through the interior fiberglass surface, inject said holes with alcohol (I used 91% isopropyl) to evaporate the water out quickly, and inject again with very slow curing epoxy. I'm planning on using West Sys. extra slow hardener. As far as I know, it shouldn't expand as it cures and creat any new voids.
Yesterday, I drilled the holes and injected 8-10 oz. of alcohol with a West syringe. Enough that all the holes seemed full, and the alc. started to flow from the aftmost holes. Then I put a small fan over the area to speed things up. I have left the shrinkwrap over the boat to preclude any rain water flowing into the holes. I also removed the stanchion and chainplate bolt, and taped the inside surface holes so I could fill those with alc. too.
It was immediately clear where the bedding had failed, and I'm inclined to rebed all the stanchions while I'm at it. I plan to over-drill, fill, and re-drill all the mounting holes, and rebed with Life Caulk.
So, I stand ready to receive your collective wisdom on the quality and/or advisability of this style of core repair in general, but also your best guesses on how long to wait for the alc. to evap., whether to repeat the alc. injection just to make sure all the water's out, and how best to conceal the tiny holes once they are filled. I haven't found a marine supply store near here that will tint a quart of topside paint, and I don't feel like messing around with gel coat.
Now to search for and post on the subject of elec. bilge pump installation....

Thanks in advance, -Glenn

S/V Sonnet II
'84 C-25 #4213
SR FK Trad.
Little Harbor NH

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/06/2010 : 09:39:21

Wow, Glenn, kudos to you for taking on a project of this nature.

Looks like you're already familiar with West Systems. They have people in their technical support department that live-and-breath this kind of repair daily - and they have a true passion for sharing their knowledge with customers over the phone. . . they're excellent!

866-937-8797

Edited by - on

GaryB
Master Marine Consultant

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4306 Posts

Response Posted - 04/06/2010 : 09:53:16

Go to the link below and read from one end to the other. There's more info than you will probably ever want to know.

I know someone on another forum who re-did the entire foredeck on their C22 using the CPES and it worked perfect. The people in customer support are supposed to be awesome too.

http://www.rotdoctor.com/products/product.html

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 04/06/2010 : 10:59:20

I bet "messing around with gelcoat" will turn out to be far less work over the long run than trying to paint and match a small section of the deck. I think that painting the deck is an all or nothing proposition.

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 04/06/2010 : 13:12:10

Gelcoat is really easy. A patch kit with tints only takes a few minutes. If you get the gelcoat in a can or jar instead of a tube, you can take out a measured amount and tint it incrementally with small measured amounts of tint until you get a good match. Then you can use the same ratios of tints to gelcoat in the container and save it for future use. Taking a picture of the hull in bright sunlight and sampling it in any photo editor will give you a rough idea of a starting point.

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 04/06/2010 : 13:43:52

What you are doing is a common method of repair, Although drilling through the wood is different than what I have done. I have drilled through the top layer of fiberglass and just a little into the wood. The alcohol part is correct for drying up the wood. Then with a pick try to lift the top layer of glass to separate it from the wood. Insert a toothpick to hold it up. This will get the resin to spread between the glass and wood. When its all filled remove the toothpicks and the glass will now be re laminated to the core wood. Top the drilled hole with the color of you choice. You may have to re drill some resin out of the hole to make room for the gel coat or Marine Tex.

Edited by - islander on 04/07/2010 14:06:35

Happy D
Admiral

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921 Posts

Response Posted - 04/06/2010 : 17:02:26

I performed the same repair. I used a syringe from the vets office. They are 60cc syringes. They are big.
I tapped the deck to outline the delaminated area. I drilled the deck at the lowest edge of the loose area so the syringe had to be pressed into the hole. I drilled a series of smaller holes along the perimeter of the delam area at 1" intervals. I put slightly thickened epoxy in the syringe and squeezed it into the delam area until it came out of the vent holes. I put a short screw into each vent hole when the epoxy showed up and screwed the outer skin to the plywood. Worked my way around the delam area and put a screw or two in the middle. Rock solid repair.

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/06/2010 : 17:07:40

Here's something from the West System website on nonskid repair - they offer different patterns for different boat brands.

http://www.epoxyworks.com/22/pdf/Ew22_Nonskid.pdf

Edited by - OJ on 04/06/2010 17:09:13

Voyager
Master Marine Consultant

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USA
5396 Posts

Response Posted - 04/06/2010 : 18:28:51

Not to contradict the experts, but doesn't alcohol contain at least some water? Wouldn't acetone be a better choice?

Edited by - on

Happy D
Admiral

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921 Posts

Response Posted - 04/07/2010 : 06:06:27

Drilling the holes and then using a heat lamp is by far the best. IMOH Acetone and alcohol just won't get far enough through the wood fibers to do any good. It takes a long time to dry out plywood.

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John Russell
Master Marine Consultant

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3444 Posts

Response Posted - 04/07/2010 : 07:39:58

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Happy D
 Drilling the holes and then using a heat lamp is by far the best. IMOH Acetone and alcohol just won't get far enough through the wood fibers to do any good. It takes a long time to dry out plywood.
<hr height="1" noshade id="quote"></blockquote id="quote">Please don't use the heat lamp in combination with the alcohol and/or acetone!

Edited by - John Russell on 04/07/2010 07:40:34

OJ
Master Marine Consultant

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4382 Posts

Response Posted - 04/07/2010 : 18:16:57

I have never used this - maybe someone else here has. It's been on the market for decades.

http://www.jamestowndistributors.com/userportal/show_product.do?pid=2093&familyName=Boatlife+GIT-Rot

Edited by - on

GaryB
Master Marine Consultant

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4306 Posts

Response Posted - 04/07/2010 : 20:09:03

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by OJ
 I have never used this - maybe someone else here has. It's been on the market for decades.

http://www.jamestowndistributors.com/userportal/show_product.do?pid=2093&familyName=Boatlife+GIT-Rot
<hr height="1" noshade id="quote"></blockquote id="quote">
I used this on the transom of my SeaRay many, many years ago. Probably around 1991 or so. The transom was starting to rot around the drain plug. It's still like steel. The stuff worked great.

Edited by - on

sailingchefs
1st Mate

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USA
28 Posts

Response Posted - 04/08/2010 : 07:14:44

Thanks to all for your thoughts! Since I was already "in for a pound" when I posted, I first took OJ's advice and called West Systems Tech.Support. I spent at least half an hour talking to an enthusiastic and very knowledgeable fellow named John. He directed me to the link for a PDF Pub. #002-550 Fiberglass Boat Repair & Maintenance, Chapter 5, Sec.1, Part 3. There I found an illustration of my exact situation and repair in progress. John said the alcohol was an excellent idea, the 91% I used being ideal, and that it would take a week or less to evaporate. He did recommend I try vacuum-bagging the area to speed it up. Apparently alcohol will boil and vaporize at a low temp. in a vacuum. I plan to surround the repair area with a bead of (clay?) window caulking and duct tape some plastic sheeting to the business end of my shop-vac. I'll run it 'til the motor's hot a couple of times, and probably call it good. It's already had a fan laying on the area for a few days.
So, a couple of other points:
-I did end up re-drilling the deck skin at the recommended 7/32 where I had gone with 5/32. A little more surface area....
-It is recommended to slightly thicken the epoxy with colloidal silica, where I had thought to leave it thin for greater penetration. I am still going with the very slow hardener, and may refill some holes a few hours later if the first application gets absorbed.
-@GaryB I decided to go with West because 1) I already have lots of it, 2) I know that it will neither expand nor contract when it cures. I have never tried Git-rot.
-@JohnRussell@Dave5041 Thanks for the reassurance on Gelcoat. It sounds fairly simple, compared to what I'm getting into now it'll be a snap!
-@ HappyD Although they do mention 'clamping' with screws in the Book of West, I can't do that here because the core is only 3/8" ? thick, and wet/punky to boot. John recommended I simply weight it down with a bag of water, or in this narrow part of the deck, a length of 4x4 with some bricks on it totalling @ 40lbs.
-@Voyager Apparently alcohol is preferred over acetone because 1) It mixes more easily with water (Hydrophilic) and 2) doesn't affect the resin in the skin as acetone might.

I invite you all to follow my adventures in barrier coating the hull, and installing an electric bilge pump.

Carry on! -Glenn

Edited by - on

sailingchefs
1st Mate

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USA
28 Posts

Response Posted - 04/08/2010 : 13:50:46

I think I've figured out how to post a photo...

and

Nice!

When I redrilled the holes, the sawdust was bone-dry! Sweet!

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/08/2010 : 14:38:10

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by sailingchefs
 I am still going with the very slow hardener, and may refill some holes a few hours later if the first application gets absorbed.
<hr height="1" noshade id="quote"></blockquote id="quote">Glenn, you may want to familiarize yourself with the curing times. I believe there's a limited time window where subsequent applications will "link" itself to the first. Once that window closes you have to sand the first coat, layer, smattering to achieve adhesion - tough to do in your scenario!

Edited by - on

Steve Milby
Past Commodore

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USA
5904 Posts

Response Posted - 04/08/2010 : 16:39:16

I just received the following email from a sailing friend, and want to pass it along:

"I can barely read this, I got the catalyst from a two part epoxy primer in my eyes last night. Just got back from John's Hopkins. They said my right cornea was scratched from it, but that it should heal by mid week. Hurts like hell and everything is blurry."

Don't underestimate the hazards of these chemicals, and protect yourself. Even a tiny speck flicked into an eye can cause a big problem.

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