Buying a canoe is like buying skis. It's just the beginning.

You will need paddles, a way to carry the boat on your car, life jackets, extra flotation for the canoe perhaps, and somebody to paddle with who knows what's around the next bend in the river.

A fine paddle can cost between $40 and $100, but for starters, Springriver and Hudson Bay sell a durable aluminum and plastic paddle for $13.95.

The difference between a cheap life jacket and an expensive one is about $20 and it's worth the difference considering what is at stake. Get the best, most comfortable one you can afford and wear it every time you get in your canoe.

If you decide to shortstop life jacket costs for a while by buying the horse-collar type, be sure it is filled with foam, not kapok, which soaks up water and sinks. Springriver sells a foam type with a heavy duty cover for $13.95.

For children, don't skimp. Get the soft vest type jacket with leg straps that keep it from riding up over the child's head. It's between $25 and $30 at Springriver and worth every penny no matter what kind of canoeing you intend to do with your children.

To carry a canoe on your car, you need a rack or a set of foam blocks and adjustable ropes. The blocks are useful for cars with sloping roofs and those without real rain gutters, but they are hard for one person to handle and are nearly impossible to use with a van or camper.

The "Quick and Easy" racks are the easiest to use if you have gutters. You can get just the clamps and add a pair of 2 x 4's to fit your car or you can use the manufacturers' metal rods. The one rack made for the rounded, fake gutters is the Yakima, which costs about $40.

To protect the canoe's gunwales from abrasion and to cut the noise of the canoe bouncing on the rack, wrap a cushion of old carpeting or foam rubber around it.

Aluminum, fiberglass and polyethelene plastic canoes have positive floatation built into the bow and stern, which helps them float right side up after a spill and makes it possible to empty the canoe and get back in.

ABS plastic canoes have flotation in the hull material but tend to sink to the gunwales if swamped and to roll over and float upside down if capsized. In open water, that could make it difficult to empty and reboard the canoe.

On white water, the canoe is vulnerable to being washed against a rock, filled with water and bent into a U shape by the force of the current. Paddlers have tried a lot of ways to add extra protective floatation to their canoes both to avoid pins and to throw off water that washes over the boat.

Scott Carter of Clark Brothers gun and outdoor store in Warrenton, Virginia, tried innter tubes, "but they have a pendulum effect." Even waterbeds filled with air have been tested.

Carter makes a set of foam blocks that fit the bow and stern of most ABS canoes. The set of blocks, with straps and D rings to hold them in place, is $29.95, plus shipping and can be ordered from Clark Brothers. It is also sold at Springriver Corporation.

The great thing about them, Carter says, is "They never go flat, you never forget and leave them at home, and they are light."

They weigh only 3.5 pounds total. They provide enough lift to keep a swamped boat riding high and upright, and in white water they throw off water t the ends, where the boat is most vulnerable.

Carter got into the "boat insurance" business after the inner tube he was using for floatation sprang a leak. He scrounged foam end blocks from a wrecked aluminum canoe. So many others wanted them that he went into the business.

For heavy water Carter adds an air bag in the center. "It gives more lift for its weight," he explained. He prefers air bags to foam center blocks because of their lift and because the blocks tend to crumble and eventually to absorb water (Carter's end blocks are waterproof).

To hold the airbag tightly Clark Brothers laces quarter-inch rope, or parachute cord, through eyebolts inserted upside down into the gunwale. "We tie the lacing with a bow so it can be released in an emergency," Carter said. Once the lacing is in place, they lay in a 3 X 5-foot Seda airbag made for open canoes and inflate it until it is tight against the lacing.

The best possible buy for good safe canoeing is a membership in one of the local canoe clubs. John Schaub, safety chairman of the Monocacy Canoe Club, say "Clubs give you a chance to talk with and learn from experienced people who know the local waters. You can see a variety of boats and equipment in use and have a chance to try them out before you buy your own stuff. You also pick up good tips on little things like tying down your boat and how to keep your glasses from falling off."

Clubs also provide handbooks which are full of solid information about safety and water levels and places to go and they offer a full year of scheduled canoe trips led by paddlers who know the rivers to be run.

Newsletters keep you up to date on new equipment and on paddling conditions. The Canoe Cruisers Association newsletter is the best place in town to find used equipment.

There are five active canoe clubs in or near Washington. Two are private and have clubhouses, docks and storage facilities. Both lean toward towards flatwater river paddling. They are listed in the telephone book and inquiries on membership are welcome. They are the SYCAMORE ISLAND CANOE CLUB and the WASHINGTON CANOE CLUB. The latter is very strong in Olympic flatwater racing.

The other three clubs have no permanent facilities but offer a range of activities. Dues are about $10. They are:

CANOE CRUISERS ASSOCIATION, P. O. Box 592, Arlington, Virginia 22216; MONOCACY CANOE CLUB, P.O. Box 1083, Frederick, Maryland 21701; and BLUE RIDGE VOYAGERS, c/o Harry Patch, 1610 Woodmoor Lane, McLean, Virginia 22101.

The AMERICAN CANOE ASSOCIATION, which supports and encourages all types of canoeing, may be reached by writing P.O. Box 248, Lorton, Virginia 22079.