Kirkland's powerful and finely tuned "A" boat turned back a strong challenge from Mather yesterday to win the House rowing championship for the third straight year.

Kirkland led all the way after a shaky start, finishing the 1500 meter course in a time of 4:51. Mather was close behind at 4:54 and Quincy nosed out Eliot to take third place with a mark of 4:57.

In the "B" boat competition, Winthrop upset Quincy by six seconds. Winthrop was timed at 3:14 for the 1000 meter race. Quincy came in at 3:20 and Kirkland trailed badly at 3:31.

But the varsity race was the chief attraction, as about 50 partisan spectators watched the "A" boats compete on a placid Charles under sunny skies.

Kirkland and Mather set a fast pace at the beginning as the Quincy, Eliot and Winthrop crews struggled to keep up. Kirkland's five oar, Charlie Sink, jumped his seat near the start but lost only about five strokes.

Mather pressed Kirkland during the body of the race with several power sets, but the Kirkland boat maintained and then increased the half-length lead it had won at the gun. Mather's final challenge in the last 300 meters was answered by an impressive Kirkland sprint that insured the victory.

"We expected to do better at our start, but after 40 strokes went by we had a good lead," Rocky Delano, Kirkland's stroke, said yesterday.

According to Stan Cox, the Mather crew followed its pre-race plan.

Cox said that Mather's strategy was to understroke Kirkland but also to prevent Kirkland from taking the stroke up too high. Mather succeeded in its first goal but failed in the second, as Kirkland rowed at a higher stroke than in the preliminary heats on Monday.

Quincy's crew was in the race for the first 1000 meters, but then fell back to a duel with Eliot for third place. Quincy barely finished ahead of Eliot, taking third by a second or less. "It was the best race we've rowed so far," said Ethan King, the Quincy stroke.

Immediately after the main event. Kirkland "A" boat rowers retired to the house of Master Arthur Smithies to drink champagne out of the Aggasiz Cup, symbol of intramural rowing supremacy at Harvard, while Kirkland's "B" boat members, less joyful, rowed the shell back to Weld Boat House.