KEYPORT, Wash. - Neither supporters nor opponents of a Navy plan to enlist dolphins and sea lions for security work at a major submarine base appeared swayed by arguments at an open house.

Critics said Hood Canal, home of the West Coast Trident submarine base, would be too cold for the Atlantic bottlenose dolphins the Navy plans to use. Others questioned the use of live animals rather than sophisticated technology.

Protesters brought inflated dolphins and sea lions clad in camouflaged shirts, while some knitted clothes for the animals.

A similar hearing was set for Wednesday night in Seattle.

The Navy has proposed using as many as 30 dolphins and California sea lions to protect the sub base at Bangor, which is believed to contain a large nuclear weapons stockpile, from suspicious swimmers and scuba divers.

Nine other options were given less favorable ratings in the Navy's environmental impact statement.

Navy officials note that dolphins and sea lions have guarded the shoreline at a similar sub base in Kings Bay, Ga., for two years.

"The animals are natural hunters," said Mark Xitco with the Navy's Marine Mammal Program. "We still hunt today but for underwater objects, including swimmers."

Working at night, the animals are trained to alert a handler in a small boat when they detect a swimmer. The handler then places a strobe light on the nose of the animal, which speeds back and bumps the swimmer, causing the light to fall into the water, where it floats to mark the spot for human security personnel to intercept the intruder.

Navy officials said the dolphins would work for a couple hours before being returned to an enclosure with water conditions similar to those of San Diego.

"That'd be like you and me going into a blizzard for two hours and then put back into a San Diego environment," said Susan Scheirman of Bainbridge Island.

Dorian Houser, a marine mammal physiologist for the Navy, countered that studies show bottlenose dolphins can handle more extreme conditions and deal well with temperatures down to about 40 degrees, which Hood Canal rarely reaches.

"For most of the year in this region you would not expect water temperature to be cold enough to be problematic, based on the information we have at the moment," he said.

Leigh Calvez of Bainbridge Island disputed Navy claims that the dolphin-sea lion proposal was the best technology available.

"We don't have anything as good as dolphins to protect us? That's hard to believe," she said.

Navy officials said other options included combat swimmers and remotely operated vehicles which have yet to be developed.

"If only we had the technology to do that," said Tom LaPuzza of the Navy Marine Mammal Program in San Diego, "and someday we will."