If you hurry, there's still time to take advantage of an offer for a sleek, seaworthy, one-owner vessel that recently was restored to the tune of $60 million. It could all be yours, absolutely free ... if you act by March 1. Oh, sure, as you might expect, there are some strings attached. For starters, your interest would be looked upon more favorably if you agreed to maintain it in tiptop condition. A willingness to keep it berthed in San Diego would be another plus. But, think of it: How soon again might an opportunity like this come along? And who would just give away such a prize in the first place? Answer: the Navy. The vessel in question is the 165-foot USS Dolphin, which was used mostly for acoustics research until being decommissioned back in January after 39 years of service. Its demise was hastened by a fire in May 2002. But the fact that other vessels in the fleet now can do the same work more cheaply had a bearing on the situation, too. Not that you'd probably use it that often, either. The Dolphin, you see, is a diesel-powered submarine whose operating cost has been in the vicinity of $19 million a year lately. As the Navy sees it, the most likely taker will end up being another department of the federal government, some nonprofit group, or perhaps an institution that would convert it into a museum.