With a wide grin creasing his strained face, the South Louisiana Pirogue Racing Champion plowed the bayou waters toward the finish line of another seemingly easy victory. He plunged the paddle deep and threw a sharp glance over his shoulder to the nearest competitor, more than eight lengths back.

Weatherbeaten hunters and tanned Cajun women urged him on in a frenzied roar of French and English - a roar that seconds later ended in astonished gasps.

"Poo-yah, dat's tough!"

With only 10 feet and three hard strokes to go, pirogue, passenger and paddle disappeared into the murky waters. The flat-bottomed Cajun canoe didn't capsize, it just sank; a victim of its own design. For the first time since any of the onlookers could remember, The Champ had llost.

Calloused hands hauled the drip-plug boater from the bayou and minutes later the disappointment was forgotten in the blur of beer and Cajun music of the Ninth Annual South Lafourche Cajun Festival .

Besides, ma boat's more at home in the marsh duck huntin' than in a race, no how," The Champ muttered between gulps of Dixie Beer.

Almost 100,000 native and weekend Cajuns from throughout the state poured into this tiny Southeast Louisiana town Saturday and Sunday for the local tribute to a heritage that has weathered modern technology, disco and dying marshlands.

The festival's organizers packed dozens of events into the weekend ranging from a Cajun dress contest and a beauty pageant to Cajun games and the gumbo cook-off and cake bake-offs. Patrons moved from the handicraft booths to food counters and bars against a continuous background of Cajun and country-western music. When the bands took their break, a disc-jockey from the local radio station added his own foot-stomping tunes.

"We're just trying to preserve some of our native Cajun culture," drawled Hughie Cheramio, one of the event's co-chairmen.

Galliano, with its 3,000 residents, is nestled between two sharp turns on Louisiana 1, a narrow, snaking highway that comes to an abrupt halt as the Gulf of Mexico 30 miles later. The town is sliced in half by Bayou Lafourche, a wide canal lined with the shrimpboats and tugboats that sustain most of Galliano's populace.

Isolated by miles of windswept marshes and a network of bayous, the community is composed primarily of Catholic Acadians - whose ancestors migrated from French sections of Canada in the early 1800s. The town's social life revolves around neighborhood barbecues and church dances, while Galliano itself is entered at the sheriff's office which handles every service ranging from tourist information to emergency fire calls. "Y'all come on down," a jovial deputy sheriff shouted into the telephone receiver.

The festival is a product of the community's fierce Cajun pride and deep religious loyalties.

"This is the offspring of a little church bazaar held nine years ago," explained the gregarious French grandmother manning the handicraft booth. Two years ago the Louisiana State Tourist Commission ranked the Cajun festival in Lafourche Parish the largest fair event in the state.

The festival is sponsored by St. Joseph Catholic Church. Eight years of proceeds have been used to construct a moder recreation facility for members of the community. This year's profits will pave the parking lot and construct a swimming pool.

The parish priests were at the heart of the action. One clergyman traded his black robes for cut-offs and a T-shirt to make a valiant but lackluster showing in the pirogue.

But, most of the thousands of Louisianians and tourists who clog the twisting highway don't even realize the new recreation center exists.

For one weekend each year, Galliano is where "la bon ton roule" - the good times roll - Cajun style.

They flock to the big tent at South Lafourche High School for the fais do-do (literally "make to sleep," from the custom of putting children to sleep during large dances) the potato dance contest, the seafood jambalaya, the Cajun music and the endless rounds of beer.

"My grandparents grew up at the Saturday night fais-do-do, but some of the kids today don't even know what one is," said Cheramie.

But, it doesn't take long for the youngsters to catch on. The Cajun band strikes up the fiddle and the accordion and a dozen elderly couples hit the floor with the Louisiana Two-Step. The next generation jumps to its feet . . . and slowly the third generation gains its courage and moves onto the floor.

But the waltz and the two-step are simple. The Cajun potato dance is the true test of agility and grace - John Travolta, step aside.

The couples stand nose-to-nose, heads bowed. A potato is placed between their foreheads and the fiddler swings into action. Arms and legs jiggle, bodies sway, potatoes start clunking to the floor. The dancing continues and more potatoes crash to the ground. Finally, only one couple has withstood the ravages of the giggles and the wiggles; they bounce to the bandstand tossing the 'tater in triumphant jubilation.

After the music, the games, the bake-off and the Sunday High Mass in the school auditorium, the festival goers get down to serious business with the annual auction.

An intricately carved duck decoy leaves the auctioneer's block for a mere $1,0000.A massive, hand-hewn motorized wooden duck which can accmodate up to seven passengers garners $2,500.

But the most expensive item on the block is the queen's crown and the honor of placing it on the head of Miss Cajun Festival 1979. This year the higher bidder sheeled out $10,000.

How do so many thousands of dollars find their way to the blue-and-white striped tent overlooking the bayou?

"You get a lot of politicans and tug-boat companies trying to impress the local folks," said one fair official. Last year's auction alone netted $61,000 for the church recreation center fund.

While the festival represents a bonton" for the outsiders, it gives the residents of Galliano a chance to prove their way of life is not an anachronism doomed to extinction.

The men and women in the pirogue races spend six months of the year poling through the marsh in search of nutria and ducks.

"These little 9-year-olds you see - they really know the business. This is more than just fun for them, it's a test of their ability," noted a boastful father.

Although most of the youngsters can't speak the French dialect of South Louisiana, they have no trouble comprehending the constant flow of French-toEnglish bandied about by the senior generation.

"Even though three generations of my family live on the same plot of land here in Galliano, I broke away and moved to the city," said one observer, a hint of the Cajun accent remaining.

"But, as long as they keep up festivals like this, our old way of life won't just disappear into the pages ofa Louisiana history book." CAPTION: Picture, Boat capsizing before the pirogue contest; by Molly Moore