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Join Date: Jun 2011
Location: West Vancouver B.C.
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There were actually two layers of plywood separated by REALLY hard grey material. It's harder than concrete although it looks a lot like it. I tried a ton of different tools to remove the grey stuff. Nothing worked well. I ended up having to beat it out with a hammer and wood chisel...took forever. There was another layer of the grey material below the second layer of plywood. Then finally fiberglass and lead below that. In all, I ended up cutting out about 4 to five inches of keel stub.
I`d bet that hard grey stuff was asbestos & resin. It was a very popular filler back then. Diamond hard after curing if it was mixed thick.
FYI - The lag bolts were extremely difficult to install in the 27/64" hole. My pneumatic impact gun couldn't drive them down. I had to bore out the holes a tiny bit. Still couldn't get them in all the way. I finally borrowed a massive Dewalt impact gun and it even struggled with one of the lag bolts.
When doing a job like this I always use a machinists caliper to check the minor diameter of the thread I am drilling for. Galvanizing has big variations in thickness and I drill for what I actually have in my hand. For example, Catalina might have come up with their recommendation by using electro-galvanized bolts which have a thin, almost shiny coating but if you were to use hot dipped, they would have the usual thick, somewhat coarse finish and would far prefer a slightly bigger hole.
Considering what materials you are working with, I`d be reluctant to use anything other than a long breaker bar to turn the socket. You SHOULD be able to run them in by hand. Using a 500 Ft. Lb. impact gun seems to me to be asking for something to strip or shear off. You ain`t bolting a bridge together.
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.