hull thickness
When I drilled the hull (#133) just forward of the ballast and slightly above, the thickness ranged from 2.5" down lowest, to a bit more than 1" a foot higher up. I drilled 9 holes and those are the averages. I was surprised how thick the hull is just forward of the ballast, right above the keel's bottom. 2.5" is no exaggeration. In fact it might be a bit more than that.
Thanks for all the replies!
The answer to the question about a tool is the Dremel Tool. I waited about a year after I started the restoration, and finally broke down and bought one. If you thought duck tape was the cat's whatever, the Dremel Tool cures colds, fatigues, makes dinner, feeds the dog, just about everything you could think of.
Now as to the hull thickness: I put a copper plate (to discharge lightning) into the bottom of the boat at the bottom the hanging locker in the cabin. That required I drill a big hole in the bottom. My guess is that the hull at that point is about 1/4"-3/8" thick. I didn't measure it but it was not as thick as I would have imagined. I also did work on the keel (drain plug) and found a similar thikcness.
My understanding is that the way these boats were laid up is they just continued to lay glass cloth layer upon layer until the weight of the hull reached the design weight. The layup was more subjective and subject to expertise - and therefore variation should be anticipated.
My experience has been that the layup was all glass cloth. I don't recall encountering any filler mat. Since the cloth is what gives the glass the strength, and if filler mat was not used, a thinner hull might be stronger than a thicker hull with matt separating the layers of glass cloth. That goes to the issue of separting the laminations mentioned earlier. Mat is relatively easy to separate, but cloth is more difficult (assuming the material was fully impregnated with resin - the mat doesn't take as much resin, which is why it can be more easily separated).
It ain't all that thick.... Today I went to do a little work on Sirocco. I have a problem with water draining down into the benches after a rain and when it pools it soaks my cushions....fore and aft. We got a great rain last night and sure enough...water had pooled in the little grooves where the wooden seat meets the bulkhead. I took a 1/4" drill and drilled into the bench, following the angle of the hull. Didn't drill far and drilled right through my hull. Water started pouring in and it pooled under the benches....would not run into the bilges. I had to drill a 1/4" hole where the vertical part of the bench seat joins the deck to drain the water which continued to flow into the bilge. Got with some guys and plugged the hole with marine adhesive and now I am going to have to pull my boat, put her on the stands and patch a hole that my "stupid" self accidentally drilled into the ULTRA THIN hull. If I were to guess I'd say the hull where I made my major boo-boo is about 3/8" thick. Maybe less
I have always loved life's lessons and as I am with a few others that I have under my belt, I'm sick about this. But, on the bright side, I'm going to get a chance to pressure blast the crappola off of Sirocco's bottom, cut those seat boards and fix them so they will lift for storage, sand and refinish the cabin sole, fix that hole and hopefully sail this Fall.
My wife told me that the next time I board Sirocco I cannot take any tools with me. She's a very smart girl.
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