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Planning core repairs around mast post

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viking299
Deckhand

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USA
6 Posts

Initially Posted - 02/26/2021 : 08:53:01

Purchased our 1998 WK C250 last summer and had a great first year, but after major rain we would find brown leaks in the cabin around the mast compression post. This winter I took the mast down for winter storage and pulled the compression post out to find the core had significant water damage throughout. Images are below.

It looks like there are multiple layers in this structure. I haven�t done much core repair, though I have some other repairs this winter (re-bed a winch and repair a soft spot in the deck) to learn with.
Any thoughts on how best to approach this repair? I am thinking I may need help from a pro and will start asking around in Rhode Island. Otherwise, I was going to remove and replace the damaged core and then repair it like a giant re-bedding project.

Thanks, Chris

Steve Milby
Past Commodore

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5851 Posts

Response Posted - 02/26/2021 : 09:17:59

What is it cored with in that area? Is the deck area around the mast base soft when you step on it, or is the gel coat cracked around the mast base? What I'm driving at is, how extensive is the damage? If it isn't extensive, you might be able to dry it out, gouge out the loose, damaged core, and then replace it with some variety of resin or filler. If it's more extensive, it might need more extensive repair.

Looking at the second photo again, it looks like the top layer is fiberglass, I can't tell what the second layer is, and the third layer looks like plywood. The plywood doesn't look deteriorated at all. I also can't tell from the photo what the large dark area is. It almost looks tar-like. Perhaps it's some kind of filler.

If the core is sound, and all it needs is to replace some crumbling filler, that would simplify matters.

I wonder if that's just a filler to seal off the air space between the deck and the inner liner?

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - Steve Milby on 02/26/2021 09:42:00

Voyager
Master Marine Consultant

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5231 Posts

Response Posted - 02/27/2021 : 07:20:26

Without being able to see the condition of the topsides around the mast tabernacle location and a wider view of the underside area, it�s tough to diagnose the extent of the core damage. As Steve points out, the plywood looks pretty good as far as the photos show. But there are several gaps in between that appear to have delaminated. Could be due to rot or freeze-thaw expansion and contraction of wet materials in the wet Rhode Island winter.

A screwdriver test may be in order to scope the extent. With the handle of a hefty screwdriver, tap the surface of the area in ever-expanding concentric circles around the compression post hole on top and bottom. Solid areas away from the areas will sound, well, solid. Soft areas near the damaged portions will sound soft and possibly hollow. With a black magic marker, chart out the suspect area around the center.

Then, get a stiff, thin wire and see how far you can push it out under the laminate and map the distance radially. It should correspond with the soft sound of the core. I think that would be your area of concern.

See if you can clean off the black stuff with a degreaser (like ZEP), Clorox, Fantastic, Acetone or another cleaner of your choice. The black stuff is either rot residue or some kind of sealer gone wrong.

As Steve pointed out, see to what extent there is any soft core material that you can scrape out or gouge out.

If it�s only limited in scope, say a radius of 2-3�, then scooping out the crud and filling the gap with thickened epoxy would probably work fine.

If the area is much larger, you could cut through the underside of the laminate with a Fine-tool blade and repair the core with fresh wood or a foam core, then replace the underside with glass and resin.

Another approach to repair the core under a large area, say a 5-10� radius, is to do the following:
Map out the area on your deck top side. Tape off the perimeter of the area to create a 3-5� buffer outside the bad area. With a pencil and a ruler, create a grid of 1�x1� lines over the entire affected area. You could also use a quincunx pattern (staggered offset rows).

With a drill-bit with a piece of blue tape on it at 3/8�, drill a matrix of 1/4� or 3/8� holes at the intersections that only penetrate the top skin, don�t drill all the way through.

Afterwards, take a finishing nail and bend about 3/4� at a right angle, put it in your drill chuck, put the nail into the hole and clear out the core in each hole. Later, vacuum out the holes to remove the debris.

Next seal any holes or openings in the bottom skin, then get some thin epoxy in a syringe and fill up all the holes with thin and runny epoxy. Don�t skimp on epoxy, keep filling the gap.

Wipe off any drips or runs right away. Make sure no epoxy can run underneath the taped off area. Wipe off the area with acetone on a rag to completely clean the top skin.
Let the epoxy cure in the sandwich between the cores. This should make the area solid once again.

There are several ways to repair this kind of problem. Don Casey�s book the Complete Illustrated Sailboat Maintenance Manual would be a great reference. You can find many of his books at public libraries, bookstores or online.

Best to read up a lot before tackling this kind of job.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Edited by - Voyager on 02/27/2021 07:31:33

Voyager
Master Marine Consultant

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Response Posted - 02/27/2021 : 07:39:45

Looking at Don Casey�s book cited above, the section entitled �Core Problems� starting on page 218 illustrate several of the methods outlined above.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

solvasoncc
1st Mate

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USA
46 Posts

Response Posted - 02/27/2021 : 10:05:28

Had a similar issue on my boat (though not as severe). Previous owner lost the mast in Hurricane Ike. It was replaced, but the step wasn't. I took it out and found this

There was a leak from the mast lighting deck plug. Beyond the deck laminate layer (which might be ok on your boat), there is a wooden block glassed between the deck core and the cabin liner. It is pretty stout. That is where most of your rot appears to be. Since the weight of the mast is being supported by the post, which goes al the way down to the keel support structures, I think the blocks purpose may be more for lateral resistance for the post or to hold the deck liner up. I think the laminated core above it (which may also be black in your photo) may be necessary to carry some of the deck weight over the span of the beam in that area (no bulkheads). I explored the rot in mine with a moisture meter and a drill and it was minimal, only at the surface, so I took off what I could, and used a penetrating epoxy in all voids, followed by epoxy and a 2x4 plus weights to push the laminates back together, then re-sealed the whole thing. Been fine going on 6 years now.

Charles

Catalina 250 WK SR Hull #475
College Station, TX

Edited by - solvasoncc on 02/27/2021 10:09:21

TakeFive
Master Marine Consultant

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Response Posted - 02/27/2021 : 17:42:14

Regarding epoxy: Be very careful about using epoxy to fill a large void through multiple holes, like Voyager described above, be VERY careful about a runaway with the epoxy. It generates heat as it cures, and if the void is large in all three dimensions (length, width, and height, just like the wood block around your mast support), it may heat up enough to boil, making a dangerous, hot, toxic, and porous mess. You may need to layer in a little bit of epoxy at a time, wait for the exotherm to die out, then layer in more. When doing this, it becomes very important to get an epoxy that is free of amine blush, since the blush prevents inter-layer adhesion. (Hint - West System is not blush-free.)

Regarding prevention: The problem of a leaky tabernackle is especially bad for keel ballasted boats that are moved to dry storage for winter. Think of it for a minute: When in water, the keel pulls down on the hull with thousand(s) of pounds of force (depending on the size of the boat), then when placed on land, the bulk of the keel is supported by blocks, and the rest of the hull will sag relative to the tabernackle (even with stands/trailer pads supporting the hull). All it takes is a few microns separation between the tabernackle plate and the cabintop for there to be capillary action that sucks any rainwater right through the cabintop.

I've become a religious user of Cap'n Tolley's, available in as little as a 2 oz bottle:

As they say, 2 ounces of prevention is worth 5000 lb of cure.

Every season when I haul out, I put this stuff around my mast step, and I can see it soaking into the invisibly small gaps. I let it dry, then go back and keep adding it until it doesn't soak in any more. If there's a rainstorm before I've finished the job, I'll always see a little rainwater on my compression post. But once it's done, the compression post is compeltely dry for the rest of the winter.

After I launch, I do the same thing again, but don't generally need it because the weight of the keel dangling in the water is compressing the mast step, so it's already sealed. But after a season of this compression in the water, hauling out the next time requires another application of the Cap'n Tolley's. So I repeat this process at haulout and launch.

I've seen this on both my prior C250WK and my current C34. I'm convinced that it is a universal problem that must be addressed on all deck-stepped boats.

In many ways, a micron-sized gap is worse than a millimeter-sized gap, because it allows water in via capillary action, but isn't wide enough to allow air in to dry it out.

Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)

TakeFive
Master Marine Consultant

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Response Posted - 02/27/2021 : 17:46:27

I'll also second someone else's warning about leaks through the mast lighting deck plug. That frequently leaks, but is easy to fix. I looked at about 8 different C250's when I was shopping during a wet fall season in 2009, and it seemed like every one of them had water leaking in around the starboard light fixture (including the one that I bought). Left unfixed, it will migrate to the wood block around the compression post, and rot it from the outside in.

Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 02/27/2021 : 22:42:00

Captain Tolley's is good stuff--I've promoted it here for years (with no compensation or connection). I believe it's essentially a very thin silicone sealer that is intended for the micron-sized cracks and gaps Rick discusses. It uses the same capillary action to draw itself into a gap, and then sets up in there. It can at least temporarily stop some leaks that should be resolved long-term by removing and re-sealing or re-bedding things with regular sealants (polysulfide, polyurethane, butyl tape, etc.), but it has its own place in cracks and gaps that are too small or can't be reached with conventional caulking. The caveat is it can be as tricky to clean up excess on gelcoat as with smears of regular silicone sealer, which can come back to haunt for years.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

Edited by - Stinkpotter on 02/27/2021 22:49:35

viking299
Deckhand

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USA
6 Posts

Response Posted - 02/28/2021 : 06:09:34

Thanks everyone for this great feedback. I have a copy of Don's book and it is very useful.

The deck is sound around the mast entry. Below is a view of the deck area (needs a scrub under where that post tabernacle was) and a top down view of the core. There is a 1 x 1ft soft spot on the cabin top deck forward and lateral to the mast, near where the electronics go down. I was planning on fixing that from below with this repair. Does anyone have experience with going through the cabin liner in the C250? Next time I'm at the boat I'll sound out how far the rot in that lower section of the core goes.

Thank you!

TakeFive
Master Marine Consultant

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2269 Posts

Response Posted - 02/28/2021 : 09:45:06

quote:
Originally posted by Stinkpotter

Captain Tolley's is good stuff--I've promoted it here for years (with no compensation or connection). I believe it's essentially a very thin silicone sealer that is intended for the micron-sized cracks and gaps Rick discusses. It uses the same capillary action to draw itself into a gap, and then sets up in there. It can at least temporarily stop some leaks that should be resolved long-term by removing and re-sealing or re-bedding things with regular sealants (polysulfide, polyurethane, butyl tape, etc.), but it has its own place in cracks and gaps that are too small or can't be reached with conventional caulking. The caveat is it can be as tricky to clean up excess on gelcoat as with smears of regular silicone sealer, which can come back to haunt for years.

FWIW, it is acrylic, not silicone. Silicone would be awful (recoat adhesion is zero), especially for cracks that reappear every year like I described in a haulout situation with compression post.

Excess or old/dirty material cleans up easily from gelcoat using acetone, you just need an old toothbrush, Q-tip, or rag with some elbow grease. DO NOT do this on acrylic hatches/windows, or you'll etch the glass.

For this same reason, be very cautious using this on acrylic sheet (mask it off), because cleanup is much more difficult. In that case it basically can only be removed with careful polishing using a plastic-compatible rouge.

Rick S., Swarthmore, PA
PO of Take Five, 1998 Catalina 250WK #348 (relocated to Baltimore's Inner Harbor)
New owner of 2001 Catalina 34MkII #1535 Breakin' Away (at Rock Hall Landing Marina)

Stinkpotter
Master Marine Consultant

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Djibouti
9013 Posts

Response Posted - 02/28/2021 : 22:08:50

Right--acrylic. I misremembered... it keeps getting more frequent.

Dave Bristle
Association "Port Captain" for Mystic/Stonington CT
PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired),
Now on Eastern 27 $+!nkp*+ Sarge

viking299
Deckhand

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USA
6 Posts

Response Posted - 03/11/2021 : 12:52:12

UPDATE: I removed all of the wet wood from the area in question. It is a substantial void, ~13" x 5" x 2". The deck above is sound. In the photo below it is the red area on the transverse beam. Due to the limited access, I think I would either need to use something like injectadeck to fill the space, or remove the liner from just aft of beam forward to the windows to get access to the space. I have a separate soft spot in the deck (other red area in the photo) which also needs repair.

Any suggestions on the best approach here? Take a large amount of the liner down for good access to both sites, or just fill up the void with foam?

https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/001019845204/media/1693965608583652/medium/1615491568/enhance" border="0">

viking299
Deckhand

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USA
6 Posts

Response Posted - 03/11/2021 : 12:56:30

Take two on image of defect area:

Voyager
Master Marine Consultant

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Response Posted - 03/11/2021 : 13:07:12

Hi Chris, Well it appears that you have good news and some bad news.
The deck is sound above the bad core, so you don�t have to do a lot of cosmetic repairs, but
There�s a large area of core that needs replacing: 13�x5�x2�

You could just do multiple small injections of thickened epoxy to fill the void without having to cut the top or bottom skins. I recommend multiple injections to let you build it up in layers and to avoid any problems with overheating exothermic reactions.

Another approach might be to use shims. A common home construction trick is to use cedar shingles trimmed to fit the space and fill in between with epoxy. You might want to try to do a dry fit first, then add glue. Again, filling a large syringe with a long tube with epoxy might work.

The other way to go is to cut back the top or bottom skin and rebuild the core with foam or pressure treated wood. This would require some degree of cosmetic patching to finish the job. Depending on the surface, you may be able to cut along the anti-skid seam or another existing feature.

There�s mor than one way to fix a Cat (couldn�t resist)... ; )

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

glivs
Admiral

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USA
822 Posts

Response Posted - 03/11/2021 : 21:04:36

Chris, Good start but many questions. If you haven't already, I suggest you initiate a conversation with Catalina asap. This appears to be a major, albeit doable, project but you want to proceed with as much understanding as possible. I have no doubt Catalina will respond to your call but be aware that it might take a few days to weeks. In the meantime I would try to dry out the area you have exposed. From your photo it appears the surfaces are still wet and the grey material (?) is weeping. Regardless of how you proceed the area will need to be dry before you can begin to seal any surfaces.

Gerry & Leslie; Malletts Bay, VT
"Great Escape" 1989 C-25 SR/WK #5972

viking299
Deckhand

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USA
6 Posts

Response Posted - 03/29/2021 : 11:20:48

I think I'm going to gain access for both this and the nearby wet deck repair from inside. I'm planning on removing the headliner from the mast to the windows, out laterally. Does anyone have experience with taking down the headliner here? Is there a gap between the headliner and the lower fiberglass skin of the deck, or is it the same layer? I haven't heard back from Catalina yet unfortunately.

quote:
Originally posted by Voyager

Hi Chris, Well it appears that you have good news and some bad news.
The deck is sound above the bad core, so you don�t have to do a lot of cosmetic repairs, but
There�s a large area of core that needs replacing: 13�x5�x2�

You could just do multiple small injections of thickened epoxy to fill the void without having to cut the top or bottom skins. I recommend multiple injections to let you build it up in layers and to avoid any problems with overheating exothermic reactions.

Another approach might be to use shims. A common home construction trick is to use cedar shingles trimmed to fit the space and fill in between with epoxy. You might want to try to do a dry fit first, then add glue. Again, filling a large syringe with a long tube with epoxy might work.

The other way to go is to cut back the top or bottom skin and rebuild the core with foam or pressure treated wood. This would require some degree of cosmetic patching to finish the job. Depending on the surface, you may be able to cut along the anti-skid seam or another existing feature.

There�s mor than one way to fix a Cat (couldn�t resist)... ; )

zeil
Master Marine Consultant

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Canada
1297 Posts

Response Posted - 04/19/2021 : 10:39:44

Chris How is the work progressing? Please update us when convenient

Henk & Johanna
"Floating", a few off your "barnacles".
"Someday Lady" '95 C250WB #151 ('03 - 2016)
"Sea ya" 30ft Bayliner (04-2018 - 09-2018)
"Mariah" '96 C250WB #191 (05-2019 - 15-05-2023)
"Lady J" '00 C250WK #499 (05-2021 - 09-2022)

Edited by - zeil on 04/19/2021 15:17:19

Tradewind
Admiral

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USA
531 Posts

Response Posted - 04/25/2021 : 11:53:43

Looks like I have a similar problem, brown water in the bilge and brown stains down the mast support inside. Mast step caulk looks OK outside but it may have been compromised during Hurricane Sally.

I'd like to hear how Chris's repair is working out.

1998 250WK #331
CILCIA
Steve
Pensacola, FL

viking299
Deckhand

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USA
6 Posts

Response Posted - 04/27/2021 : 11:26:06

Mid repair update. As noted above, I�m confident now that the water around the mast through hull and in the deck core came from the electrical fittings. The big four plug was dry, but the two single wire plugs had wet core that I�m going to repot and reinstall the electrical fittings.

The water intrusion leading to the soft spot on the deck I tackled with injectadeck. I didn�t want to deal with going through the headliner or replacing the non-skid (especially around the curves of mast compression post / windows). Not the ideal repair but it seems quite functional.

https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/001019845204/media/1698218019455636/small/1619547004/enhance" border="0">
Going to finish with some grey marine tex.

The brown liquid came from a wooden block that the mast post went through in the transverse stiffener. It was a large chunk of wood as noted above, but didn�t run the whole length of the stringer and only straddled the mast. Not sure what the point of this was. It must have been rotten for some time and the deck is solid above so I�ve removed the remnants and am leaving as is. No feedback from Catalina on the function of this. I�m going to seal the exposed deck core above and rebed the mast post with butyl tape, but otherwise am not planning significant work here.

Last step will be the rebed the mast electronic connectors. Not sure what connectors I�m going to use here yet, any recommendations?

Next project is to replace the core around the starboard cabin top winch and stanchion. Easy access underneath thankfully.

Splash date is 5/14!

JB
Navigator

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110 Posts

Response Posted - 04/28/2021 : 07:42:39

Thanks for sharing this information. I'm sure it will be very valuable to others in the future. I just hope we don't lose the pictures again.

1988 C25 Wing Keel Std Rig Tohatsu 9.9 Tiller Steering and 2003 C250 Wing Keel Std Rig Inboard Diesel Wheel Steering

Edited by - JB on 04/28/2021 07:44:15

Robb
1st Mate

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Canada
31 Posts

Response Posted - 07/10/2021 : 08:48:41

Thanks for starting this thread Chris. I was a bit concerned about water infiltration at this location and after seeing your post I took out the mast step and inspected the wood: to say I was relieved when I saw it was in excellent condition is an understatement. Before I re-bed it with Sika 291, I'm going to brush on some un-thickened epoxy resin to seal the wood in the event of a leak in the future.

Robb
2004 C250 WK hull# 739

Robb
1st Mate

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Canada
31 Posts

Response Posted - 07/26/2021 : 12:16:37

Update. Although the wood was in good condition - no rot - there was some evidence of minor water staining on the wood but it was dry. I did pull the mast step/pole out and found about 2 oz of water in the base (cup) that the mast step/pole covers when its all the way down. Cant figure out how the water would get there as the mast step/pole are a sealed unit. Previous owner must have got some water on the cabin sole and went up between the pole and base. I did remove the water and reinstalled the mast step and pole, making sure it was well sealed - including the electrical connectors.

Robb
2004 C250 WK hull# 739

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