CROTON-ON-HUDSON, N.Y. - An hour's drive from the heart of New York City can take sailing enthusiasts to a world of their own. Here on Senasqua Bay, where the Hudson River is at its widest, you can learn to sail, brush up on boating skills or charter a boat for a day cruise.

One recent Saturday, at the helm of the 34-foot sloop Karis for the first time, Nancy Cohn of Croton called, "Ready to come about! She hesitated for a moment, then asked her instructor, "Is that right?" It was.

The crew, two novice sailors and the instructor, on hand to give guidance and to take over if something goes amiss, scrambled about the deck releasing some lines and tugging on others to pull the sails into position.

The instructor, Steve Roux, a 30year-old South African expatriate, spent nearly a dozen years at sea before settling on land to get an engineering degree. He teaches sailing on the side at the Croton Sailing School, where one can learn to sail in two weekend sessions.

"There are few cowards in sailing, but plenty of fools," Mr. Roux said. "I try to limit the number of fools."

'Patience, Not Pressure'

Steven Jennings, the founder and owner of the school, said all instructors were certified and "use patience, not pressure" to teach the fundamentals of sailing.

Beginners are taught on 24-foot Rainbow sloops. Weekend lessons begin at 9 A.M. and end at 4 P.M., with an hour break for lunch. Three-hour refresher courses can be arranged for the morning or afternoon.

All you need to bring is boat shoes (sneakers will do) and comfortable clothing. A hat, sunglasses and sunscreen are also recommended. If you pack a picnic lunch, you can eat it at Senasqua Park, the site of the school.

Half-day sails leave part of the day free. If you've come by car, you can visit downtown Croton, which has a few delicatessens and a pub-restaurant called Elmer Suds, just off Grand Street, the town's main street.

Another recommended eating place is Scooter's, about. three miles out of the center of town on Route 9A. Hudson Pirate's Cove, across the road,. serves fresh seafood and is a little grander, although docksiders without socks are by no means out of place.

A Scenic Waterfall

For scenery, head to the Croton Dam Gorge Park and picnic at the foot of the Croton Dam, which was built between 1892 and 1907 and which was the second largest masonry structure in the world when it was built. Recent rains have filled the vast Croton Reservoir, and water rages over the dam's spillways, creating a scenic waterfall. The reservoir provides New York City with a large portion of its water.

To take in some local history, visit Van Cortlandt Manor, the house of Stephanus Van Cortlandt., the first native-born mayor of New York, and his descendants. The house, built during the late 1600's, has been restored to its post-Revolutionary war d6cor, and contains many original artifacts from the Van Cortlandt family.

Guides, dressed in period costume, demonstrate bread-baking and other kitchen tasks and describe some of the day-to-day activities of colonial life.

Also on the Van Cortlandt Manor grounds, which once covered 68,000 acres - most of Westchester County are beautiful gardens, a replica of an early Dutch settler's home and the Van Cortlandts ferry house, which once served as an inn and pub for travelers on the Albany Post Road.

To get to the Croton Sailing School by car from New York City, take the West Side Highway to the Henry Hudson Parkway; follow it to the Saw Mill River Parkway, and then to the Taconic Parkway. From the Taconic Parkway, exit onto Route 129 heading west. Stay on 129 until you see signs for Senasqua Park and the Croton Sail School.

By train take the Metro North Hudson Line from Grand Central Terminal to the Croton-on-Hudson, stop. The sailing school is a two minute cab ride from the station.

For more information on lessons pr charters, or to make reservations, call the Croton Sailing School at (914) 271-6868.