Since VHF is line of site putting it atop the mast gives you a little more range. The coast guard has tables that can show you just how much.

However, if you lose your mast you lose your antenna and if you put it up there your putting a pound or so at the end of a 30 foot lever arm which isn't good for boat stability if you want to stay light.

On Wildthing we used to have a stern pushpit mounted antenna which I just removed along with the radio in favor of a waterproof handheld model (standard horizon) and an earpiece. That was 3 years ago and so far so good (In the bay I listen more than talk... talking is for cell-phones). If I were to go back to a fixed radio I'd put it back on the rear push-pit stanchion if racing, if doing offshore or non-racing I'd put one on the mast with a backup on the stern.

-bryan

:: What do folks do with their vhf radio antena?- nothing?
:: masthead? off the stern stancions?