Since the days of Cleopatra's barge, a proper yacht--the kind yachtsmen call a gold-plater--has signified the ultimate in excitement and luxury afloat. Although the cost of a modern gold-plater sail yacht in the 80-foot range can easily run into hundreds of thousands of dollars, the shared cost of a chartered cruise aboard, for a compatible group of fun-loving aquanauts, adds up to little more than they'd pay for a landlubberly vacation at a class-A resort. With this in mind, a party of four couples recently chartered the kingly ketch Sorrento--and looked forward to a salty, unique vacation sailing the bounding main. They were not disappointed. Flying to the Windwards in the eastern Caribbean, our partygoers assembled on tiny Young Island--just off St. Vincent island, where the Sorrento lay to her moorings (right). The intrepid voyagers that night initiated their eastern Caribbean idyl with an anchors-away boarding party. And early the next day, the expedition's four beauteous members--Elaine, Pat, Judy and Roxanna--got the trip off with a splash by taking a secluded natatorial plunge. Our shipmates--ably instructed by Captain Tim, his honey-of-a-blonde wife, Lisa, and three-man crew--soon received a taste of yacht racing: Weeks before, at their request, the Sorrento had been entered in a regatta. But even though their ship finished out of the money, the Sorrento's carefree clan was only too happy to hold a victory buffet party, all hands toasting the occasion with tots of rum. Next came a tour of the Tobago Cays and the Grenadines; and, somehow, in the midst of their action-packed days and starry nights, our charter-cruise members were also learning to sail and navigate. Their days filled with water-skiing, swimming, snorkeling, spearfishing, sun-bathing and island exploration, and nights with cocktail parties eagerly thrown at the drop of an anchor, the charter seemed to end all too soon. But when the Sorrento's vacationers finally boarded their homeward-bound jet at Castries airport on St. Lucia, a happy thought kept the journey home from becoming a sad one: Having savored the sweet life of charter yachting in the Caribbean, our eight adventurers were making plans for a return engagement.