WELL, HELL, FELLA," Joe Sottosanti said, "if you're going to go to the races, you might as well compete. It's no fun just standing on the bank watching people down."

"Forget it, Joe," the suburbanite said. "I've only done a few hours of whitewater canoeing in my life, and half the time I was swimming."

"Nothing to worry about," he boomed, straining the telephone line from Luray. "We'll race together, you can be my bow man. The rapids are only Class III and IV. We'll go a few days early and by race time you'll know the rocks like your baby's bottom."

"No thanks. I'm 30 pounds overweight and I'm out of shape. I'd just make a fool of myself."

"Everybody makes a fool of himself in whitewater. That's what makes it fun. Besides, I'm 50 pounds overweight and in worse shape, and I'm old enough to be your father, almost.Hell, we've got six weeks to get ready. We may not win, but I guarantee we'll finish near the top, unless we wipe out."

"Now look, Joe . . . "

"You start exercising tonight and I'll get the entry forms ready," he roared on. "See you in Petersburg the last week in March." He hung up.

Thus it came to pass that on Sunday last the suburbanite found himself in the front of a 16-foot canoe on the North Fork of the South Branch of the Potomac at Mouth of Seneca, W. Va., wearing number 84 and feeling distinctly out of place in a horde of whitewater enthusiasts.

"Just steady on is all it takes," Sottosanti said. "We've been down the river together six times in practice and the only difference is that this time we're going to paddle harder."

Downriver an endless line of speeding canoes dwindled in the thin spring sunlight. Along the rocky bank above the starting line hundreds more scraped and banged as they queued up.

Canoes were sent off two at a time at one-minute intervals on the 10-mile race. Nos. 75 through 97 were in class C2-S, which means two men in short, open craft. The other C2-S pairs were for the most part younger, and very much lighter, so that their canoes rode higher for less drag in the water and a better chance to clear the rocks that stud the sparkling river like dragons' teeth. They looked fit and confident. Shoulders bulged beneath their life jackets and sinews writhed along their forearms as they handled their canoes smartly, backing and steadying while the starter counted down. The suburbanite was feeling sick.

Then one pair, jockeying for position in the faster part of the stream, got caught crosswise and leaned the wrong way. Everybody cheered and laughed, not cruelly, as the men capsized in the icy water. A pair of boats fouled each other and promptly hung on a rock a few yards past the starting line, costing themselves precious time.

"I told you not to worry," Sottosanti said. "We're all turkeys in this class. Just keep your eyes open and we'll burn these guys."

The remark about keeping a sharp lookout was pointed: Sottosanti refuses to wear glasses, and without them his world is a misty gray adventure in which objects smaller than an elephant are likely to pass unnoticed. Since the stern man largely controls the course of the canoe, it behooves Sottosanti's bow man to give timely warning of such things as boulders jutting out of the water dead ahead.

Part of the morning had been spent rubbing wax into gouges that practice runs had put into the canoe, which was a green Royalex built by Sottosanti's Shenandoah River Outfitters and modified to balance as well as possible the nearly 500 pounds it was being forced to carry.

"Go 84!" friends on the bank shouted as the starter counted down. Some deft work with the stern paddle put 84 a canoe-length ahead at the line, and No. 85 faded during the half-mile sprint to the first rapid.

"One down, nine to go," Sottosanti said. "Is that a wreck up ahead?"

Canoes were piling up at the rapid as a pair from an earlier class struggled to pull their aluminum canoe off a rock in the center. In the pool below, a half-dozen more were dumping water or chasing stray paddles. The stuck boat cleared and was almost overrun by those following.

Sottosanti and the suburbanite had neglected to practice running the first rapid, which was above their camp. "I got caught under the canoe and almost drowned here once," Sottosanti had said as they stood on the bank and watched others run it. Most hit one or more of the three rocks that lurked in the chutes; some came through sideways, backwards or upside down.

"We'll decide which way to run it on race day," he had said. "The water level's dropping every day, and the chute keeps changing. Maybe we'll pull out and portage around."

Nothing had been decided on the morning of the race, and the suburbanite was so rapt watching other contestants the boat was at the head of the rapid before he noticed. He pulled the bow left with a draw stroke as Sottosanti steered the stern to the right; the canoe went through almost sideways but without a hitch.

"See? Nothing to worry about," Sottosanti said.

An earlier C2-S entry was left behind in the pool, and another, carrying a pair of Boy Scouts, was hung up in the following rapid. "Three down," Sottosanti said. "Let's get it on. "

The suburbanite's shoulders were cramped and burning, with the race hardly begun. He already had switched to a smaller paddle; Sottosanti stroked steadily with a paddle as broad as a breadboard, standing up along stretches of quiet water for more power.

"This is where the race is made," he grunted as he drove the canoe after the leading boats. "Pass them in the slack water and you'll break them."

Each time the broad paddle bit the water the boat surged a foot closer to a pair of canoes that had started four minutes earlier. Both were aluminum, which put them at a considerable disadvantage in the low water. ("I've never seen the North Fork this low in the spring," one of the race officials had said, "This would be a hell of a river if it had some water in it.") Plastic or fiberglass canoes slide over rocks where metal boats stick as if spot-welded.

The distance closed sharply at a shallow rapid, and 84 was bow-to-stern with the aluminum boats in the pool below. They increased their stroke rate frantically and stayed ahead for five minutes or so, but another shallow rapid seized them as Sottosanti drove steadily on.

"Five down," he said. "You know, we could win this race."

A half-hour had passed, something like 2,000 strokes. The suburbanite, feeling the strength draining from arms and shoulders, began to pivot from the hips, holding the upper body rigid. His belly muscles, long neglected beneath a layer of suet, were cramping.

"Can't quit," Sottosanti gasped. "The other guys are hurting too."

Just past the halfway point 84 passed a dozen boats stranded or timidly picking their way through a long jumble of rapids and shoals known as the Rock Garden. It felt good to leave them behind, but it would have felt better if they had had C2-S numbers.

"Low numbers, low numbers," Sottosanti growled. "Look at that, we're chewing right through the big boys' class. But where are the shorts? We've got to catch some more shorts."

One of the shorts, it turned out a few minutes later, was clawing up from behind, showing a number that meant it had left five minutes behind 84 and so was running that much faster. The pursuing boat blew a rapid and fell back, but soon came up again and breezed by.

"Well, there goes first place," Sottosanti said. "That's a glass boat; no way we'll ever catch them, that's a pure racing boat and it can run almost a third faster."

Because this year's Petersburg races, sponsored by the town and the Canoe Cruisers Association of Greater Washington, were also the Middle States championship, racing boats were run together with "cruising" canoes, which is like running sports cars against station wagons.

Miles 6, 7 and 8 of the race were a blur of pain and fatigue. Although there no longer seemed to be any power in the strokes, 84 overtook two score more boats. Only one of the whole bunch was a C2-S; 84 slammed that boat aside, after the style of the chariot race in Ben Hur, when it blocked a narrow passage like a cork in a bottle.

But an hour had passed and the suburbanite's ears were buzzing. He was calling out course corrections too late, and Sottosanti was reacting too slowly.Here and there in rapids and shoals 84 touched one rock, then another, losing momentum and seconds.

Out of nowhere two C2-S boats came steaming up. No. 84 held them off through one tight passage but touched a rock in the following rapid. One boat slipped by, and then, as 84 wallowed in the foam, the other rammed into the stern, driving 84's bow solidly aground. One of the enemy paddlers said something jocular as they went by; the suburbanite said something rude.

"How many is that? I've lost count," Sottosanti said. "Too damn many," the suburbanite said, looking back upriver at other C2-S boats gaining.

With two miles to go, anger supplied the drive that the suburbanite's self-discipline had failed to produce. He began to develop power and pace to match Sottosanti's, and the pursuing boats dropped back. Soon 84 was close enough to three of the boats that had passed for their numbers to be read.

The last mile, mostly slackwater paddling around two sweeping curves, was a creditable sprint. But the men in the leading boats had something left also, and the gap still was 50 yards at the finish line. Lack of steady effort by his bow man had held Sottosanti to a 12-mile pace in a 10-mile race.

When the results were up 84 was sixth of 21 boats in 1:23:45 point something, four seconds out of fifth place, a minute out of third, four minutes behind the winning fiberglass speedboat, which apparently had faded in the homestretch and conceivably could have been caught.

On the other hand, a couple of boats did not finish; their occupants maybe among those contestants hauled off to the hospital in the ambulances that periodically screamed along the highway paralleling the river. The last-place C2-S pair was 35 minutes behind 84.

A few hundred strong strokes where he had dabbled, the exhausted suburbanite thought, and a little better direction-finding in half-dozen rapids, would have yielded third or even second. But Sottosanti, who once had won the C2-S class and had always finished several places higher, didn't say that. All he said was, "Good race, Partner."