Michael Hurd of the British Royal Air Force and Jan Yerkes of Bucks County Comunity College crossed the finish line in the fifth annual Marine Corps Marathon yesterday believing they had not only won their races but set course records in doing so.

They were shortchanged.

According to A.J. Vander Waal, who measured the course for The Athletic Congress (TAC) certification, the marathon course was about one-third of a mile short of the required 26 miles 385 yards.

Vander Waal, who remeasured the course last night after the race, said, "In four different places, they (runners) departed from last year's course. The sum total is that it is 1,725 feet short. There's going to be 9,000 unhappy runners tomorrow (9,307 runners started the race)."

Asked how this could have happened, he replied: "With the Marines if you are within one-half mile, it's close enough. They are not concerned with preciseness of times and distances. It's like horseshoes. Close is good enough."

vander Waal said the course had been shortened in four places and that in two of those the changes appeared inadvertent and in the other two they seemed preplanned to avoid traffic.

Between the 12th and 13th miles, he said, runners cut diagonally across Pennsylvania Avenue, losing 214 feet. Between the 15th and 16th miles, he said, they lost another 168 feet when they were directed across footpaths and grass along the mall instead of on the roads, as the course was set.

On Ohio Drive in East Potomac Park between the 18th and 19th miles, the lead runners were sent through a parking lot instead of following the drive all the way around the point, cutting 1,125 feet off the course. That error was later corrected for most of the field.

At the Tidal Basin, between miles 22 and 23, runners took a path along the water and then cut across the grass of the Jefferson Memorial instead of staying on the road. The net loss there, he said, was 218 feet.

Shortly after the race, Will Albers of Fairfax, who finished fifth, and Laura DeWald of Arlington, who finished second, reported the irregularities to race coordinator Jay Paxton. Paxton said the irregularities would be investigated. He could not be reached for comment late last night.

Navy Lt. Cmdr. Phillip Camp (third place), noticed the changes at the Tidal Basin and Hains Point and said yesterday afternoon, "If we did cut off the course it was no fault of the runners. There was Rosie Ruiz out there today."

Vander Waal said he would report his finding to the TAC-Road Runners Club of America joint certification committee headed by Ted Corbitt. "No doubt the certification is gone," he said. So, the outcome will remain the same "obviously, if it's 1,700 short, there's no way the times can stand," he said.

To compute their actual finishing times, Vander Wall said runners should multiply their time in seconds by 1.012625, which will equal their corrected time in seconds. Then they must reconvert that time to hours, minutes and seconds.

By this formula, Yerke's time (originally reported as 2:39.53) becomes 2:41.54, technically still a course record and much better than her previous best marathon of 3:00.43. Hurd's time (originally reported 2:16.55) becomes 2:18.38, 31 seconds more than the course record set by Scott Eden in 1977.

It could be enough to prompt the spray-painter from Sulffolk, England, to leave some wanted graffiti in Washington. Last year, Hurd finished 27th, after leading until the 14-mile mark. Roy Bulley, the RAF team manager, said, "Last year, when he crossed the finish line, he said, 'I'm going to come back here next year and win . . . '"

Asked last night about the reported shortening of the course, Bulley said, "We've got the winner. We're happy."

By the 2 1/2-mile mark, Hurd was among the leaders, running in a pack of about 20 runners including Albers, Camp and Mike Greehan, who would finish second in his first marathon (an uncorrected time of 2:17.46). They kept each other company all the way through Georgetown, up the Mall and around the Capitol to the half-marathon mark (reached in 1:09.44), which was a good thing, since once again the city provided so little in the way of companionship.

As they turned the corner onto C Street, the pack broke and the pace picked up. It had been about 5:20 a mile; now it shrank, to 5:10 a mile, with Greehan, Albers and Hurd running together and Camp trailing just behind.

At 14 1/2 miles, Greehan took the lead and held it for the next 7 1/2 miles. They swooped down Ohio Drive, toward Hains Point and the mythical wall, accompanied by a flock of blackbirds in the annual southward migration. "It was dumb to be leading the whole way on Hains Point," Greehan said. "It was half-miler tactics."

Albers, who had been counseling Greehan that there was a long way to go, overtook him at the Tidal Basin between 21 1/2 and 22 1/2 miles. They both thought they had left Hurd, hurting, way behind (60 yards).

But they were wrong. Albers, the leader last year until the 23 1/2-mile mark, midway across the 14th Street bridge, met his Waterloo there once again. "I don't hit the wall," he said. "I hit the bridge."

Hurd, 34, was feeling the after effects of the cereal he ate for breakfast but caught Albers, now in second place, on the bridge. He caught Greehan, the greenhorn, 1 1/2 miles later, at 24 1/2 miles, right after Hurd was taken ill by the side of the road. "It was bothering me since 21 miles," Hurd said. "It came up, my head cleared and my stomach cleared. I guess that's what you call the pain barrier."

Greehan was dumbfounded.

"They said I had broken him," he said, shrugging. "Everyone was telling me how demoralizing it is to hit the wall. I'll tell you what's demoralizing. mIt's having a 20-yard lead at 24, looking back and seeing the guy throw up and then you look up and he's at your shoulder smiling.It was that smile that broke me more than anything else."

Hurd gained 57 seconds on Greenhan in the last two miles. "I was flying," the airman said.

Camp, who passed Albers at 24, said, "I'll tell you what's demoralizing. It's finishing 1 1/2 minutes faster and getting third."

Yerkes, 23, a student at Bucks County Community College in Newton, Pa., who has won the last 20 races she has run (including a 1:17.56 half-marathon in September), was leading at three miles, when the favorite, Sue Petersen of Laguna Beach, Calif., cruised by. "I passed her at six," said Yerkes. "I was scared. I get nervous when someone passes me. I do dumb things like trying to go too fast."

She had no further cause for nerves and no reason to feel dumb. She led for the last 20 miles, running between 6:00 and 6:10 a mile, 20 seconds faster than she had anticipated. She didn't look back. "I didn't want to see anything."