The Canoe Cruisers Association doesn't really have any way of keeping boneheaded novices out of its annual whitewater race on the Potomac, which runs this Sunday.

Or does it?

To be in the race, you have to get to the starting line. That's enough to weed out the beginners all by itself.

"When I go canoeing I like to put the boat in and go," said a paddler last week. "You can count me out of that Potomac race."

Registration for the CCA race is from 9 to 11 at Great Falls Park in Maryland. The first boat doesn't leave the start until 12:01. That should tell you something.

It is a long way from registration to start. A long way over very unfriendly terrain, in sneakers, with a 55-pound boat balanced on your head. That should do it.

Some spectators don't even stick around for the race. They come early to chuckle over the procession of legs with canoes for heads skipping from rock to rock along the perilous Billgoat Trail.

The walk is said to be 5/16ths of a mile, but it feels like about three times that.

No matter. Once at the starting line a great camaraderie takes over as every form of river canoe, from streamlined kayak to burdensome Grumman, is launched and joins a giant pool of competitors waiting for the starting gun.

Last year well over a hundred boats made the seven-mile plunge from Wet Bottom Chute just below Great Falls to Sycamore Island below Glen Echo.

This is a race for anyone with some basic knowledge of whitewater canoeing. There are fast-burners and old CCA stalwarts who simply use the race as an excuse to do the river when it's at its best - just as spring floods die back to summer doldrums.

Early last week the Potomac was at a perfect level for racing, and indications were that it would stay that way. The CCA likes a reading of four to five feet at the Little Falls station, and on Monday it stood at 4 1/2. That means the race should go off without a hitch.

Last year two women whose names will not be mentioned ran the race, one of whom had absolutely no prior experience on the river. They probably should not have, as the CCA asks that no one under intermediate paddling capacity take part.

Hateful fate. They finished third in their class and never took on a drop of water.

"That's the key to this race," said John Lentz, who runs it to win and who this year passed by the opportunity to share his canoe with a somewhat humbled newspaper writer. "The winner is the one who never picks up the bailer. The best route is the driest route."

That isn't always as easy as it sounds. Along the seven miles are four thumping sets of rapids. The first, only 50 yards from the start, is the worst. Spectators who stick around at the start can expect a good view of a few boats going gurgle gurgle right at Wet Bottom Chute, which earned its name.

There follows two miles of hard paddling through the Mather Gorge, a rock-walled canyon where the water flows swiftly but levelly. Then Difficult Run, which earned its name, appears.

Difficult is run on the Maryland side. There's a huge rock island in mid-river and fast water on either side. One is in no danger of falling asleep there.

Two miles or so below Difficult the flat water churns up again into Yellow Falls, which is just past Offutt Island and Goat Island. There's no easy way around it or its successor, Stubblefield Falls, both of which are negotiated on the Virginia side.

Yellow and Stubblefield require the paddlers to push through sturdy standing waves, and as Lentz pointed out, the boat that gets through with the least water generally will have the better time.

From there it's an easy flat-water paddle to Sycamore Island, where cheering throngs greet the racers, however slow their times. CAPTION: Picture, THE DRIER CANOE WINS. By James M. Thresher.