The Canal Clipper, a 30-ton cement-hulled mule-drawn barge was plying the dark waters of the C&O Canal north of Great Falls last night when it struck a submerged rock and began taking on water.

Although nothing of the kind had ever happened in the memory of National Park Service crew members, there was no debate over whether the 87-foot-long craft was or might be unsinkable.

About 10:15 p.m., two miles or so north of Great Falls, the order went out to the 45 persons aboard to abandon barge.

With the vessel showing a decided list, the mules that furnish its motive power were reined to a halt. On board, two park rangers tore up a piece of plywood decking and turned it into a makeshift gangplank.

The passengers, members of the Bon Vivant Club, an organization of travel agents and airline representatives, filed across the plank from the tilting barge to the safety of the towpath.

"It was quite an experience," said one passenger, Jack Kerrigan.

With a ranger in front and a ranger behind, the survivors, all uninjured and none even wet marched down the towpath through the blackness of the night to Great Falls, and their waiting cars.

The barge, which is available for charter, once operated from the Georgetown area, but is now based in Great Falls while the Georgetown section of the waterway undergoes repair.

Park Ranger Mike Crandall said the barge struck the submerged obstacle about an hour and a half into the trip, as it was turning aroud to return to port.