The lead keel is not under the main mast. I went through this a couple of years ago without much luck but I did determine that if you drill straight down under the port edge of the sink and about a foot forward of the engine room bulkhead, you'll see lead shavings appear when you've drilled down about two inches. I used a large lag screw and connected the
ssb ground to it with a hose clamp and it works just great. I'm assuming that your galley sink is against the engine room bulkhead and to the starboard side of the steps as mine is.
John
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