Sail power for profit -- a shipping concept that disappeared after the introduction of cheap fossil fuels -- could be in for a rebirth.

A couple of American entrepreneurs have independently built two hybrid sailing schooners that mix the minimal costs of sail power with the reliability of diesel engines. Last year, in the boat village of Deltaville, Va., Joe Spivey launched his 70-foot, steel-hulled Sharon Virginia, named, in the Chesapeake Bay tradition, after his wife. The schooner, modeled after designs for turn-of-the-century Chesapeake Bay workboats, uses the diesel engine for docking and getting under way, but relies mainly on wind power.

The 31-year-old graduate of Virginia Commonwealth University set up business as Working Sail Inc., and offers to haul "anything, anywhere." The Sharon Virginia's 20-ton hold carriesabout a semitrailer load of cargo, and Spivey says he can carry goods for about 25% to 35% cost savings compared to dieselpowered vessels. Last winter Spivey headed sonth to carry cement from Miami to Nassau; in the spring he returned to the Chesapeake Bay to ship seed oysters from riverbeds into the bay; and this past summer he hauled oak lumber from Virginia to Miami.

Meanwhile, in East Islip, N.Y., Greg Brazier built the Phoenix, a vessel similar in size to the Sharon Virginia, in his backyard. It was launched in the spring, and Brazier plans to work the route from Port Jefferson, N.Y., to Bridgeport, Conn.

"The trucks have to travel a 75-mile route," Brazier says. "I can provide scheduled service on a regular basis through a 15-mile water ronte, at a price as much as 50% below what truckers charge now. "

The concept of sail power for profit is spreading. Companies in California and New England are experimenting with large sail-assisted boats to transport cargo over long distances. And there is now an industry association, Sail Assisted International Liaison Associates, based in Norfolk, Va. About 150 people attended its first convention last May.