You want the hole filled
Rapp: You, of course, don't want to remove the threaded locking bolt and have nothing in the threaded hole. If you did, water would pour out of the hole when your boat is heeled to port. If you must remove the locking bolt, get a stainless steel bolt of the same diameter and pitch and screw it in and seal the hole, probably with silicone sealer, and possibly with an "O" ring. The bolt must be short enough so that it won't touch the keel, either when it is up or down, and there is a difference in these two lengths. We always use our locking bolt, unless we are motoring the boat into really shallow water. We haven't had any problem with it. I have described how we keep it from leaking below.I did tape the cross pin of the bolt so that it remains like a "T", rather than an "L". This small detail makes it much faster to screw the bolt in or out. I also have a sticker that tells how many turns it should be loosened to wind the keel down, and how many it should be loosened to wind the keel up.We've had our C-22 for 25 years, and after a while you just do these little things.Aldo