core

deansh · Post by **deansh** » Wed May 11, 2011 11:30 pm

I've recently purchased a SJ 21 and have been reading many of the forum posts concerning rotten balsa core. On my boat much of the forward balsa is wet but not rotten. The fiberglass is stuck tenaciously to top and bottom. I cut about a foot wide section of glass from below and tried to pull off the bottom sheet of fiberglass but the balsa would tear irregularly. I was hoping to just dry the core out and re-glass. This apparently will not work. Any suggestions? Thanks Hal

Ben G · Post by **Ben G** » Thu May 12, 2011 10:50 am

No experience here, but I understand the underlying concern with balsa rot to be a soft/spongy deck. In other words, a structural issue. If you feel that the boat is safe, sail it for this season and save the big project work for off-season.

On some of the other forums, I recall there are some good photos and description of a re-core. In one case, the owner flipped the boat over, to make the actual work easier.

deansh · Post by **deansh** » Thu May 12, 2011 11:03 am

My deck not spongy at all but now I have a 1' x 3' section of core removed. May as well do it right at this point.

San Juan Sailboats · Post by **San Juan Sailboats** » Thu May 12, 2011 12:20 pm

Now that you have holes, the balsa should dry.
Now you need to seal the holes in the top.
On Chamred Juan, I removed all the deck hardware, drilled 1/2" holes where all the through deck holes were, gouged out the balsa about 3/16" back from the hole, then filled with epoxy. Re-drilled the holes and installed the hardware.
Now even if the fastener holes leak, they won't get into the balsa.

I used an allen wrench cut back and the end sharpened on the end of a drill motor to do the balsa removal.

Krysia Ry · Post by **Krysia Ry** » Fri May 13, 2011 12:46 am

Stephen is right. Last summer at nationals (I think it was), I remember someone saying how keeping a fan inside the boat for a whole year dropped the weight of the boat by drying her out. You could drill a number of small holes on the inside and try that. Also when sealing your boat, do as Stephen says and use a bent nail or allen key and clear each spot ( chain-plates, winches etc) of old wood, then tape (I use tuck tape) the inside cabin top and fill the holes with epoxy. That way if the hardware leaks, it will no longer intrude into the core. It is one of the projects I've been working on. Check out Don Casey's site for more ideas on repair.
Good luck and fine sailing
Bill

TomD · Post by **TomD** » Fri May 13, 2011 12:55 pm

Not sure if you have seen this site yet but this SJ21 owner did a great job of documenting his deck repairs.

http://sailing.thorpeallen.net/Quasar/

Diarmuid · Post by **Diarmuid** » Fri Jun 10, 2011 4:43 am

Another method for clearing out the core material prior to epoxy injection, and one I found MUCH easier than the bent nail/allen wrench technique, is to drill up from below with a bit at least 2x the fastener diameter. You can put a stop collar on it if you like, but I found it very easy to tell when the bit first contacts the outer skin. This method leaves a nice, clean hole w/out loose shreds (which can be hard to vacuum or blow out), and it's no harder to tape over when injecting your epoxy. And you can inspect the quality of each cured plug as you peel the tape off.

I did about 50 holes that way during our recent recore -- in literally 5 minutes. I sharpened the drills to a low angle with minimal relief, like a sheet metal or masonary drill, which reduces their tendency to aggressively self-feed. You could use a masonary bit, too.

Don'tcha wish Clark had thought of doing that at the factory? Oh the heartbreak it would have saved.

patrick · Post by **patrick** » Tue Jul 12, 2011 11:41 pm

I'm just about to get started working on the core and had a couple of questions about the bent nail/allen wrench technique. Do you drill the larger holes from inside the cabin and stop before reaching the outer skin (in order to leave the outer skin intact)? Also, should I remove the bow pulpit and rope cleats and do the same to these holes? Thanks!
Patrick Caruso, MK II, Spokane, WA

cklamp · Post by **cklamp** » Wed Jul 13, 2011 2:49 am

Patrick,

large hole in the outer skin, small hole in the thin inside skin. I'm honestly not sure about the bow pulpit/cleats but I've never heard anyone say they did.

later
C

Capndar · Post by **Capndar** » Thu Jul 14, 2011 12:18 pm

If you can get the boat under cover and get a dehumidifier (llike for a basement) and put it in the boat, it will dry the boat out nicely...

Mike "Come Race at Labor Day" Robinson
#1694 Ragtop
Lake Norman YC

San Juan 21 Class Association

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