Rotten balsa layer below deck .. need advice :(

LISVin · #1 (**permalink**) 10-06-2007

Currently trying to renovate a 67' Meridian (25') .. here is my most recent headache.
Due to poorly bedded deck hardware (previous owner!), the layer of balsa that is glassed underneath my fore deck is all wet and delaminated from both the topside and inner skin.
It's not everywhere, but a significant amount of it is ruined.
I have removed a small sample portion using both an angle grinder w/cutting wheel (for inner skin) and a peice of sharpened sheet metal for the balsa.
Unfortunately, this process is SLOW .. and it looks like the majority of the balsa has to go.
Any suggestions for speedier removal of this compromised material?
Any help greatly appreciated.

bils · #2 (**permalink**) 10-06-2007

I had a J30 with similar probs...
We drilled 1/4 inch holes in the deck around the area. Then took long nail bent at 90 degrees and used a drill to chop up the wet balsa in between the deck. we then sucked as much as we could out with a shop vac. Then let it dry out. we then filled it with epoxy and put new touch up gel coat on the drill holes - hope this helps.

NOLAsailing · #3 (**permalink**) 10-06-2007

I do not recomend the drill and fill method for anything larger than 1'x1'. Otherwise, it is more of a band aid than a repair. Removing the old core is a hard, dirty job, but there aren't many shortcuts. You can try carefully using a chisel or a metal paint scraper and hammer to get the still adhered core out. Once that is done, take a sander and prep the surface.

Another tip - before replacing one square of balsa, have your method for bracing the new core established - it won't stay up on its own.

I don't have much time now, but I'll try to remember to repost a more detailed description of the job later today. I have to do the same job (on my J/30, bils) when it cools off some - not looking forward to it.

bils · #4 (**permalink**) 10-06-2007

Yeah for a large area - I agree. Another suggestion I saw someone do to an old T10. He came from under taking the headliner off and leaving the deck surface intact. He made a mold b4 and I cant remember how he refilled the area. but I know the deck was much stronger there after as I was on the foredeck quite a bit.

southerncross31 · #5 (**permalink**) 10-06-2007

I recored the cabintop of my boat. I cut off the outer skin with a skill saw set to just over the thickness of the skin. Using a heat gun and chisels/scrapers i removed the wet core. Then i ground the inner and outer skins clean and wiped them down with acetone. Then wet out the new core with unthickened epoxy, filled the cutout with sillica thickened epoxy (use enough so there are no voids under the new core and so the epoxy oozes out of the cut). Let it cure for a few hours (but not dry) then cover the top of the core with thickened epoxy, wet out the skin and drop it in place, again ensuring there are no voids. Then place weights evenly over the surface of the outer skin and let it all dry for several days. If you could do the same thing from inside the boat, you would have less trouble making the decks look perfect. However it seems to me that it would be way more messy, epoxy would be dripping on you everywhere and the amount of dust, fumes it will create may kill your lungs and skin. Fiberglass dust is nasty stuff!!!!

sailingdog · #6 (**permalink**) 10-07-2007

One way to do it is to use a router, to cut out most of the balsa, and then finish up with chisels and scrapers. I would highly recommend you do it from the top down, not the inside out, since gravity will work for you, not against you, and you'll have more room and better ventilation and lighting. YMMV.

USCGRET1990 · #7 (**permalink**) 10-07-2007

Some sites to check out that you may be able to retrofit to your problem:
http://www.rotdoctor.com/
http://www.seawolfindustries.com/seacast.html

US27inKS · #8 (**permalink**) 10-07-2007

I replaced a lot of core in my old US27. The boat had been neglected and the interior needed to be gutted as well, so I worked from the inside. The best tool I found for cutting the interior fiberglass was an air powered 90 degree die grinder with a rotozip DC1 bit. The spiral rotozip bits are worthless for this. Gravity will work against you from the inside, but your work is easier to hide. You can apply pressure against your core from the inside with a piece of thin plywood jacked up against it. Just like the outside, you can also save the inside skin to reduce the amount of fiberglass work.