The migration back to Westchester's waters is in full swing. Like flocks of birds, flotillas of recreational mariners return each spring to the Hudsoii River and Long Island Sound. Sailboats and Motorboats come down from their cradles and out of winter storage.

Ted Kamp, public affairs officer for the United States Coast Guard Auxiliaries First District (which covers New York, New Jersev and Connecticut), said that there were 10,000 to 12,000 sailboats and powerboats in Westchester's section of the Sound and an estimated 5,000 to 7,000 boats in the county's stection of the Hudson River. In addition, kayaks, canoes, rowing sculls, Jet Skis and Hovercraft get underway.

All these recreational boaters find that one type of sailor never left the water. Thanks to the protective powers of the wet suit, wind surfers enjoy the longest season. They even thrive on the small craft warnings of winter. Bogdan Prokopczyk, a scientist from Peekskill, put his wind-surfing board back into the water in March and takes vacation time in May to catch some gusty wind. No summer doldrums for him.

It's an All-Year Season

"Our boating season goes all year, and besides the wind is better in the winter." Explained Loren Korevec, who sails his wind surfer on Haverstraw Bay every month of the year.

Some avid wind surfers and twin-hull sailors subscribe to the Wind Hot Line, enabling them to get up-the-moment wind speed and wind direction conditions at 10 stations in New York, New Jersey and Connecticut. "I have wasted a lot of time chasing wind that wasn't there," Mr. Korevec said. "The hot line is great." (The hot-line number is given only to subscribers to the service. For further information, call 617-864-7940.)

When the wind is right, area wind surfers zip effortlessly across Haverstraw Bay or along the river off Cold Spring. But Mr. Korevec warned that wind surfing off Croton-on-Hudson was not for beginners, because of the tide, the currents and the big wind blowing over a wide expanse of water. "Sometime it's like being in a blender," he said.

At-,Milton.Harbor in Rye, wind surfers find calmer waters. Tony Natiello, director of the Duriand Nautical Training Center, for the Boy Scouts of New York, said it is an excellent place to learn this sport. "Kids are up on their boards after two days of lessons, and if 50-year-olds want to learn how to windsurf, we can teach them," he said.

Although the moorings at Senasqua Park in Croton-on -Hudson were put in On April 21, the boating season got Off to a slow start, said Steve Jennings, who runs the Croton Sailing School., "We've had some rain, high winds and even tornado warnings. But the winds here provide for what we call the white-knuckle sailing," he said.

The Croton Sailing School of Croton-on-Hudson, offers sailing and sculling lessons, as well as rentals and Hudson River cruises. Call 271-6868.