Acid does a good job of ridding plugs of zinc, but on a boat, I find it troublesome to stow it or use it. Instead, I drill the zinc out of the plug doing the following: Since a broken off zinc usually leaves a raised point, I'll use an oversized drill to cut down the point, using the tapered edge of the plug to center the drill and the subsequent dimple. In my case, the zinc having 5/16 threads, I'll start with a drill which is as wide as the plug, something less than 3/8. Once a center dimple is formed, I'll start drilling a hole with as small of a drill, attempting to keep the hole centered. Once that drill pops through the bottom of the zinc, I'll start increasing the size of succeeding drills until I get as close to the threads as I'm comfortable, or until the 5/16 tap, using standard tapping technique, can be worked down through the threads. If a new zinc will not tighten adequately, I throw the plug out; after all, I'm no further behind than when I started. Occasionally I'll come across a zinc with poor threads, then I just chase the threads with a correct size die, in my case 516. I'd love to hear of other approaches to ridding a plug of broken off zincs. *Rudy & Jill Sechez * *BRINEY BUG-a 34' Sail-Assisted Trawler * *Anchoring Consultants-trawlertrainingabc.com* *850-832-7748 * *Georgetown SC Northbound-Chesapeake*