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Drying out the Core

9K views 34 replies 18 participants last post by  CalebD 
#1 ·
Can anyone tell me how to dry out the core of a delaminated deck without ripping the boat apart? The deck is solid. The surveyor believes that the failure is recent enough that rot hasn't set in yet, and suggested epoxy injection as a cure. From what I've read about epoxy injection, the core should be dry. The boat will be spending the winter in dry storage in North Carolina.
 
#2 · (Edited)
IMHP you cant dry it

And if it was in there long enough to delaminate it was in there a long time

People do all kinds of tricks like drilling small holes and spinnining things to to chew up the wet material and get it out and then inject epxoy
 
#3 · (Edited)
The drill and fill method is purely a band-aid - and not a good one at that. If the core is wet enough to separate the bond, then it's very wet. If there is any softness at all in the deck, then it's mush. There's no easy way around it, unfortunately. The drill and fill method will only make a proper repair that much harder when you have to deal with all the little epoxy plugs. I may have a photo of what the deck looked like on my Triton when I recored to properly fix an area that I previusly attempted to drill and fill; I'll post it in a bit if I can find it.

EDIT: Here's the photo. Not the best, but you can see a lot of the plugs: these were hard to remove for a clean surface for recoring.

 
#7 ·
Forget about trying to dry it out... you're much better off doing a re-core, since it will be simpler and neater in many ways... it will also be far stronger. The inject epoxy idea blows chunks... and leaves an ungodly mess. Don't do it, especially if the area in question is larger than ONE SQUARE FOOT. It's not worth it.
 
#9 ·
If you're looking for a winter project, come on over and shovel our driveway!:D

Good luck with the recore and take some pictures so the we can all gain experience (and entertainment) from the process.
 
#10 ·
my survey said there was some moisture, but all i needed to do was rebed everything on my deck and it would eventually dry. I have no delamination. was considering running my dehumidifier in the boat too. am i lying to myself to think this would fix this situation?
 
#13 ·
my survey said there was some moisture, but all i needed to do was rebed everything on my deck and it would eventually dry.
You might want to consider a new surveyor and one who actually knows something about deck construction and deck repair. It will not dry in your lifetime. What he might have meant was re-bed so no more water gets in and the little bit in there won't cause much harm.

Fill a canning jar with water then put the lid on (or bed the hard wear and seal the deck). Guess what in 50 years there will still be water in the jar....
 
#11 ·
No, if it's just a bit of moisture (it doesn't take much to peg a moisture meter) and you eliminate the source of the problem, you should be fine. Make the call when you see the core while rebedding. In addition to new sealant, isolate the core from the fastener holes by potting the holes with thickened epoxy (let me know if you need details on this process).
 
#12 ·
Since my original post I've had opinions from a second surveyor, a boatyard, and a crusty old sailor a few slips over. The consensus pretty much was:
1> Yep, it's wet in there. Mostly the side decks. Probably came from the leaking ports.
2> The deck isn't spongy, so this is not a crisis. Nor is the boat unsafe for your use.
3> Fix the leaks correctly so it doesn't get any wetter. It probably won't get drier.
4> Someday you're going to have to tear the deck off and fix this mess. If you stop the leaks now, someday could take several years to get here.
5> Sail on and enjoy your boat.

Bear in mind, I'm strictly coastal. All advised me that I shouldn't take on a serious passage. Not a problem since I'm going to do that in a Catalina 30 anyway.
 
#14 ·
It won't dry unless you take extreme measures. The reason is simple. Drying takes evaporation into a dryer atmosphere. Evaporation occurs from a surface. Water in cores is capillary, the relative surface are is near zero, so drying does not occur.

I've tried a vacuum pump, pulling a really hard vacuum for 24 hours, and got zip. Cut away the surface and the void was full of water still. The boat had been sitting with large hole saw holes open, in a dry shed for six months already!

I think you could do it with heat. You'd have to get the fiberglass right up to 212 degrees or a little above so the water is pushed out by boiling bubbles. I once tried to epoxy a cast iron keel and couldn't get the epoxy to go off. A week at 180 degrees, as hot as I could get it with an electric heater, and the epoxy finally cured. Subsequent coats were no problem.

I've thought about using high temperature self regulating heat tape, and covering the surface with fiberglass insulation. That would probably work but the tape is quite expensive. I've also used a welder and a long piece of ordinary building wire as a heater. You just dial up the current until you get the heat you need.
 
#20 ·
If it is bigger than one square foot... it generally needs to come out. Also, it depends on the area and what kind of loads it is under. The side deck may have greater loads on it if it is near the chain plates or has to support the chain plates or the genoa track...
 
#21 ·
It won't dry out. Take it from the sailors who have spent countless hours ripping out their core. When you make the first cut water will pour out.

Check my blog for pics and comments on this exact subject. Check the links at the bottom of the blog, they contain info I have gathered for this same exact subject. Escpecially the "rattle and hum" blog(goto first post).

Mango Madness J30 #185 rebuild
 
#23 ·
Can you show us a picture of the porous glass around this screw? I would more likely guess that it squeezed out from behind the fender washer and not through the fiberglass? Old Tartan deck skins are usually quite thick.

This is a fairly standard piece of balsa cored deck laminate. The drill is a 5/16" bit so as you can see these skins are certainly thick enough to not be porous. I would not believe your Tartan is constructed much differently.
 
#24 ·
No, it was difinatly coming thru the glass. (inside) I was quite surprised to see it. I backed off the screw a bit and re-tighted. Same result of water coming thru small pores in the interior glass. Water drops appeared on the inside surface of the coach roof in 10 or so areas around the screw (covering maybe 6" x 6")when the core was compressed by tightening the screw.
 
#27 ·
'

While I've never heard of it or seen it you may have osmotic blistering going on between your deck skins. Now that's WET!!!

I would drill a test core, in a known dry area, to get a look a the thickness of the skin laminate. If it is anywhere near the thickness of the previous photo then my guess is that your deck is so wet that it's blistering from being water soaked. Perhaps the added heat from the sun on the deck has accelerated the process??
 
#25 ·
If you are actually able to squeeze water through the glass skin, I would be more concerned about the integrity of the lamination. I am in the process of repairing several large areas of wet core and delaminated core on a 1972 Pearson 30. Some of the araeas I am working on the core was fine, not delaminated but just soaking wet, other areas must have been wet for a very long time and the balsa core was like mush , like maybe rotted oatmeal and in these areas the skin laminations themselves had succombed to the constant soaking and had begun to become pourous and soft, the entire structural integrity of the laminations had failed. SO if you can squeeze water through the skin lamination I would say that you not only have to replace the core but the skin lamination itself is justy as big an issue. SO drying out the core(if even possible) still leaves you with suspect laminates. My recomendation?..Get out the grinder and cut off the offending area of skin, scrape (or pour out) the rotted, mushy core and replace the core properly and relaminate a new skin. I have just finnished the aft port side of the cockpit seat by going from underneath, it is hard working upside down from under the seat but the outer skin is perserved. I will do the ame on the starboard side. These areas let water in via the travelor mounting screws. The other area is the cockpit sole,aft of the center of it where the fuel fill is located, about the aft two feet of the cockpit sole and around the rudder post. This I will do from the top side as, for one thing, there is hardly room enough below the sole to do this kind of work. I removed the fuel tank but it still is very tight squeeze. Also, the outter skin(topside) has flexed so much due to the rooted core that the laminations are beginning to fail so cutting that out and relaminating a new outer skin is the only sensible thing to do IMHO. Also, It will go alot quicker working from the top, as well as much easier. The whole deck will get re-finnished (painted) when all these repairs are complete.
 
#26 ·
That is kinda what I was thinking. The exterior surface is intact and has no problem at all. The issues are only visible fromt the inside. Core does seem spongy (mush) with the water coming thru interior laminate. Area is 2' x 1' of te interior coach roof. Very easy access now that the headliner is out.

Can someone point me to a discussion "how to" do the core replacement, materials to use, directions, etc...? I've not done glass work before, but happy to start.
 
#28 ·
That is kinda what I was thinking. The exterior surface is intact and has no problem at all. The issues are only visible fromt the inside. Core does seem spongy (mush) with the water coming thru interior laminate. Area is 2' x 1' of te interior coach roof. Very easy access now that the headliner is out.

Can someone point me to a discussion "how to" do the core replacement, materials to use, directions, etc...? I've not done glass work before, but happy to start.
Before you rush into things buy yourself a moisture meter so you know exactly what and where you are dealing with. You can buy one for under $200.00 delivered from Electrophysics in Canada. This expense will, in the long run, save you money.

Read this for more info.

Understanding The Moisture Meter (LINK)
 
#29 ·
Core drying takes a long long time. My old boat had wet core problems, it was on the hard for over a year. I did some of the work and a contractor did some of the work. It cost a fortune and took lots of time and hard work. Between a very knowlegdable surveyor, myself and the contractor, we came up with a solution that should let the boat be sailed coastal only for a very long time; no blue water passages.
 
#31 ·
So after spending the winter some 800 miles from my boat, we are finally back together. I driled some core samples in the area in question. Moisture, yes. Running water, not even close. The fiberglass came out as dry powder, the wood came out as normal, but wet, drill shavings. Glass and core are firmly attached, and it is virtually impossible to pick apart the core. I am using heat lamps on the surrounding deck, and things appear to be drying out nicely. I plan to drill more core samples and repeat as needed.

It would naturally follow that there is a time period between origin of a leak and complete destruction. The problem would be that this sort of thing isn't noticed until the deck is squishy, whereupon it's too late. As for me, it'll be a complete rebedding, regular checks with the moisture meter, and early action of future problems. She's an old boat, she doesn't have to be pretty.

Thanks to all for your input. Fair winds!
 
#33 ·
Sorry to hear about the deck problem. I have a similar problem on a 1973 Tartan 41. This is about 5th on my list of major repairs prioritized by safety at sea issues such as keeping the rig up. Pease let me know your plan of attack and what materials and information you have gathered. From what I have learned so far, the best way to proceed is to remove all the hardware, peal back the top layer of glass and remove and replace the core. I would like to do just the "soft spots" but I am afraid that the once I get into it the "spots" will expand to include most if not all the deck area. I also am thinking of experimenting with attacking the problem from underneath the deck..... ???
 
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