J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Wet vermiculite

Yes, vermiculite is the stuff that looks like insulation under the teak.

No, the Aussies eat Vegemite on their sandwiches. I've tried Vegemite... once... and I think I'd prefer eating a sandwich of wet vermiculite.

On hull #337, the area under the vee berth does drain into the bilge. There is a limber hole in the teak where it meets the glass floor of the head. This regularly gets clogged, but jabbing around in there with a wire fishing aft will generally clear the clog so that it can drain aft to the area under the head floor, which in turn drains aft into the main bilge. This does work... but as with any boat, debris tends to clog the limber holes and narrow spaces where the water is supposed to flow.

Ok, so I have a head shower...not that its ever been used in the head...I stick the handheld nozzle up for rinses at the shrounds. But the water that rains down my mast "simulates" an inside shower...which makes its wat into the bilge by holes, when unclogged. No tubing etc. My guess is that all the stuff under the teak gets wet at some point... and I hope that it continues its merry way. Is Vemiculite SUPPOSED to collect water? What is its purpose...just stiffening? Mine's "cracking up" if you will...

Was there any damage other than the vermiculite cracking? Mine cracked too after hitting a rock, but I don't see any other damage. It was dry and solid, so I have to think that it was adding to the stiffness of the boat i.e. nothing else cracked so that was the stiffest portion (even though not the strongest of course.)
Can't imagine though that vermiculite under the floor boards actually is required for the structure.

There are *no* stringers on the floor aft of the keel, so I'm of the opinion that the vermiculite sandwich between the hull and floor is in fact a critical stiffening component.

As evidence in this forum, a hard grounding flexed the hull enough to crack the vermiculite. That's some serious force when you consider how tough that vermiculite is (think rock). Now imagine that grounding with no vermiculite tying the floor and hull together in a big cored sandwich... I'd wager that you'd get a lot of deflection in the hull and some corresponding damage.

Does cracked vermiculite warrant replacement? I really have no way of knowing this. In my opinion, relying on vermiculite to stiffen the hull like this is not a great design, but I thing it does the job. A set of glassed-in stringers would transmit the load much more reliably and broadly than a blob of what amounts to brittle stone. The cracked vermiculite has probably lost some of its initial stiffness, which means this area can now move more than before. Is it a problem... no idea, but I'd personally repair it if I was going offshore.

Look at the stringers in a modern Beneteau (pg3):
http://www.beneteauusa.com/pdf/why.pdf

This is the latest evolution of stringers - a bonded molded superstructure, which is becoming the norm these days. This recent design by a presumably informed naval architect should give you an idea of how seriously at least one manufacturer takes distributing the load around the keel. The J/30 is a proven tough boat with its original construction, but I'd seriously question depreciating any part of its structure, even if it looks like a rice krispy treat from hell.

Rich