We center punched it and drilled a 1/4" pilot hole using the drill press.
It took about 10 minutes to drill down a little over an inch, when the it got easier to drill, and the filings were darker and finer. We were definately drilling into the cast iron.
Catalina had said that the studs were J cast in to the keel casting. We somehow doubted this, and decided to try a pipe wrench on the others. Low and behold, the next two bolts unscrewed from the keel, having approxiately 1" of good thread into the keel:
The rearmost bolt broke off. We drilled a 1/4" hole about 1" into the center of the broken bolt, and tried a stud extractor. With a little bit of leverage with the pipe wrench, the stud extractor broke off in the hole!
SHIT!!!
I called Colin Cunningham from Newcastle, and he came by with some more tools.
We tried to get the extractor piece out with various drill bits, CNC bits, dremel bits, but the steel is VERY hard, and we could not get anywhere with it quickly. We decided to move onto the other studs.
That left the frontmost bolt, and it also sheared off. We ground the two front ones smooth, center punched, and drilled 1/4" pilot holes:
We then drilled out the middle stud to 1/2", and started to tap with a 5/8" tap. It was slow and difficult; we used a small square to make sure the tape was true.
A 5/8" tap requires a 17/32" pilot hole. This is 1/32" larger the the 1/2" pilot hole we had. We decided to head to Princess Auto to get a proper pilot bit to make the tapping easier. Princess Auto, Home Depot, and RONA don't have this size.
I did pickup some rings with 1/2" thread on them at Princess Auto.
I was able to thread them into the two good original holes and hook up the keel to the overhead crane.
Now you need a stud extractor extractor.
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