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jedlls 08-19-2010 07:21 PM

Wet balsa core
How much moisture in Balsa core can be tolerated?
How do you evaluate moisture content and do as little cosmetic damage as possible?

I got a moisture meter, found 2 wet areas on the cabin top, what's next?
Drill a few 3/16" holes in the outer skin and see what's in there?
If it's not black and rotting or empty in the core persue the drill holes and to dry out the core?
If it is rotten then:
1 cut off the outer skin, grind out the rotten stuff; re-core; replace skin as per Don Casey's book?
2 Can the hole drilling to dry out core method be used over anti skid?
3 If the area of rot is small; forgo the grinding and just rasp out the rotten core area (6" x 12"); flush with acetone then 202; pack the space back up with structural putty; and have a lot less cosmetic work. I can access the damage from the improper fitting holes that allowed the water in.

Can anyone give me advice? Could you also relate your experience?

CrazyRu 08-20-2010 02:14 AM

Can you access the area from inside? I would drill test holes from inside, see how much rot is there.

tempest 08-20-2010 07:08 AM

Any idea where the moisture is coming from? Deck hardware? Handrails?

I just went through this with the handrails along my cabin top.

I removed the handrails, drilled a larger hole where each screw hole was ( I think it was a 1/2 inch ) it was no larger than the base of the handrail, and no deeper than the headliner. I did the allen key in the drill thing and dug out all the wet balsa around the larger hole. Dug a little deeper around with an awl. Let everything dry out for about a week. ( we had a dry summer)
Then filled all the holes and voids with epoxy. Re-drilled new holes for the handrails and re-mounted/ bedded.

I think the important thing is to find the source of the leak. ( probably through some hardware ) You can probably live with some moisture in the core on the cabin top if it's not structural. If there's alot of water in there, it will freeze and thaw and cause cracking.

How old is the vessel?

GaryTorello 09-07-2010 03:14 PM

IMHO drilling holes and applying products such as Git-rot, etc just prolongs the time before you need to tear it apart and do it right. Once the wet core has become either a safety issue (busting thru a deck is not pretty), or a structural problem (near jib tracks, etc.) it's time to do it. Prior to that if you can STOP the water intrusion early, a slightly wet deck can be lived with for a number of years.

mitiempo 09-08-2010 04:27 PM

I don't believe you can dry core by drilling holes. If it is wet cut and remove it. And of course cure the leak(s) that made it wet to start with. If the core is wet and you seal it in all it takes is warmth to promote rot in the near future. As well if you are far enough north for winter freezing the freeze/thaw cycles will possibly cause delamination if there is enough moisture present.

LandLocked66c 09-08-2010 08:47 PM

Take care of it now, help your boats next owners! Ask me how I know! :D

deniseO30 09-08-2010 08:52 PM

Here's a thought.. drill holes in the bottom into the core but not through the deck, use a pattern so it looks intentional. all the moisture will dry out from below... just a thought.

mitiempo 09-08-2010 08:54 PM

Especially if all the holes overlap.

Remember it didn't happen overnight. Balsa core that has it's end grain covered in polyester reain as it is bonded to the deck and liner doesn't absorb water easily and will not give it up very easily either.
If you put a piece of wood in water end grain first it will absorb water easily. Now seal the end grain with epoxy or polyester and try the same thing. Very little is absorbed other than by the end grain of any wood and if it isn't going in easily, which takes years inside a deck, it isn't coming out easily either.

LandLocked66c 09-08-2010 09:06 PM

There is no easy answer... Either seal it up best you can and live it. Or dig in and repair it properly. Like you read in Don Casey's books is the best route to go.

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