The Navy Academy flexed its backboard muscles, oiled its fast-break offense and ran away from Manhattan College, 84-73, today at Halsey Fieldhouse.

Looking at times as if they were playing a practice game, the Midshipment controlled the boards, 41-24, including 22-7 rebounds in thefirst half points, was usually at the receiving sion lead. Major beneficiaries of the battle for the boards were Kevin Sinnett, who led Navy with 22 points, and Hank Kuzma, who added 16.

"The name of the game is to control the boards, there's no mystery to that," said Navy coach Bob Hamilton. "Anyone can run an impressive offense when they're getting all the missed shots."

The Middies were never more impressive than early in the first half when, treiling 10-8, they reeled off 10 straight points and were never seriously threatened. Kuzma and Barry Wilbur, each of whom had eight rebounds, started the break. Guard Bobby Scott, who had six of the 10 points, was usually wt the receiving end of outlet passes.

"That just killed us," said Manhattan coach Jack Powers, who hasn't lost to Navy since 1973. "They were just running wild. We were never really able to catch our breath."

Navy stretched its lead late in the second half to 74-57 on a dunk by Brooks Boatwright, who came off the bench to add five rebounds.

Sinnett, who had 14 points in the first half, was nearly unstoppable for the first few minutes of the game, whirling to the basket and hitting one-handed jump shots. Then Scott and his speeding teammates, Lee Latenick and Rick Wilder, started to control the tempo.

Manhattan, like Navy, entered the game with an 11-10 season record. The Jaspers' Rick Marsh, who led scores with 24 points, hit from every angle to keep the Jaspers from an even more disheartening trip back to New York.