Rivots
I suggest riveting. But if you intend to use screws, I suggust using stainless machine screws and tapping the mast. Use Loctite on the threads. (don't over tighten, you can strip the mast). Let the loctite and corrosion freeze the screws in. Use the semi permenant Loctite. My favorite screws for small masts and booms is 8 or 10-32tpi. You need 4 turns in the metal to get a good bite. Self tappers although quick and dirty tend to invite trouble. First, if the pilot hole is to small, the threads will cold weld to the mast and the head will tear off leaving a sharp post that will not come out without effort. If the hole is to large.. the mast will strip and you have to move up to the next size. Also the the Self tappers tend to loosen more than the machine screws since only one to two threads will be in contact with the metal. (don't go cheap on screws. cheap self tappers will shear quicker than well made ones.) This is true even when self tapping into fiberglass. Don't reach into the box and pull leftover screws from a garmin or CD-player installation. Mac masts are pretty thin for the drill and tap method, this makes rivoting my choice. You can always go up to the next size rivet if the hole is too big. (or move the gooseneck to expose new meat - your call). If you dont want to buy a rivot gun... they do sell hammer rivots at marine supply stores. If you use stainless rivots (very strong) remember to coat them with an anti corrosion compound. This will protect the mast from corosion since it will be lower in the metalugical food chain. Either way will work and you will get at least another 5-20 years out of it. Then it'll be time to move the gooseneck a half an inch. to get to new metal. Good Luck and fair winds.
