PHU QUOC ISLAND, Vietnam – “We have to be ready to fire, but we also have to have a smile on our face.”

In those words Gunner Mate 1C R. J. Kajer described the unofficial mission of the Navy’s Swift boats plying the waters off southern Vietnam in the Gulf of Thailand.

“The biggest part of the job is checking for Viet Cong sampans,” says Kajer. “We’re a bit like traffic cops. But we try to make friends too.”

Still the crews must be ready for anything during the sampan searches.

Everyone at the An Thoi base on Phy Quoc Island remembers the day earlier this year when the Viet Cong sank one Swift.

A VC flag fluttered from a buoy a few hundred yards offshore. A Swift pulled alongside and a hand reached out and yanked off the flag. It would have made a nice souvenir.

But a mine ripped the Swift’s hull. The VC had been waiting on the shore and they exploded a hand-detonated mine. Four men died and two others were injured. The boat sank.

The memory of that incident helps keep the men alert.

Still, they frankly admit that one of their biggest problems is fighting boredom – not the VC. Ironically the Swift crews created their own problems, for their patrols have helped cut VC traffic to a minimum.

The 50-foot-long Swifts are out for 36 hours at a stretch and do most of their patrolling at night.

In a busy night, a Swift stops and searches 20 sampans. The patrol might find only freshly caught fish or vegetables on board, or they might find communist guns and ammunition.

The Swifts are one of the Navy’s answers to the patrol problems encountered in the waters off Vietnam. In close to the shore are the junk fleets, farther out are the 82-foor-long Coast Guard patrol gunboats.

The radar-equipped Swifts were introduced into Vietnam last Oct. 30. The all-aluminum boats travel at 20-25 knots and carry twin 50. caliber machine guns mounted in a turret, an 81mm mortar and other armament.