None of the three noticed their little boat filling with water.

It's sort of thing you could overlook if, say, you were busy fighting a 150-pound sailfish off the coast of Central America.

"As I reached over to bring in the sailfish," said Robert Campbell, "all of a sudden I found I had water up to my knees."

During the hour-and-a-half fight with the huge fish a wave came over the stern and lifted off the battery-Compartment hatch. The three were too busy to notice it - or that the boat had been slowly filling up.

Campbell, 37, and his friends, Sandra Corea, 24, and Joseph Almond, 29, watched helplessly as the stern of the 200-footer was swamped and most food and equipment was washed overboard. The three climbed up on a small area of the bow - held up by flotation compartments - and hung on for their lives. It was now dark. They were adrift, the 6-foot waves and 35-mile wind pushing them out - far out - in the Pacific. They worried about sharks that lurked nearby. They watched nervously vulturelike birds that circled and watched them. They battled thirst and depression. They prayed.

Campbell asked Corea to marry him if they made it back alive. Almond agreed to be best man, but had his doubts that he ever would be.

Their thirst was the worst problem. "We were worried about our mental condition, how long we could keep it together," said Campbell. "We watched our water supply going down every day."

On the sixth day the wind and waves abated. Campbell and his companions then were able to bail out the boat and get it floating normally.

By the eighth day adrift, their water rationed to one-sixth of a glass three times a day, their throats so parched it hurt to talk, they caught a sailfish with one though in mind - to drink its blood. Campbell, who kept a diary in his checkbook and passport, wrote:

"We made the incision at the gills. Beneath, in the corner of the bait well we placed a small container to collect his blood. We let it drian until we have several pints. Joe takes it first. I detect his poorly concealed grimace as he passes the blood to me. The blood is coagulating rapidly but I manage a couple of quick gulps. A wave of nausea passes . . ."

Despite getting the liquid in the blood, their greatest danger was still dehydration. An important protection against the sun was the boat's canvas Bimini top.

On the 12th day, desperate at being blown away from the sealanes where they might be picked up by a passing ship, Campbell, an experienced yachtsman - ocean racing, yacht delivery skipper and a Coast Guard captian's license - made a life-or-death decision, captain's license - made a life-or-death decision.

He pulled down the canvas top and converted it into a primitive square sail. This exposed them to the sun but gave them a little control and a little forward motion. They headed the boat toward the Mexician coast, hoping to be picked up by fishermen.

At midnight of the 20th day, Campbell heard a noise and awoke. It was a freighter passing 200 yards away. They had seen 37 ships, but none apparently had seen them. Almond had seen too many ships pass to get excited about this one. "I'm going back to sleep," he said.

"No, no, he's turning," Campbell told him, The three screamed in unison. Even as he recounts the story, as safe as one can possibly be back in his officer here in Washington. Campbell sighs, a sense of relief passing over his face, as re remembers that 38th ship.

"By God," said Campbell his new wife at his side, "he really was turning."

Campbell had been assigned to Nicaragua a year ago as head of a tourism development project by the Washington-based Robert R. Nathan Associates, Inc., consultants in economic development Corea, a Nicaraguan. On July 9, they set out for a weekend coast of Nicaragua, with their friend, Almond a fishing guide.

They were just about three-quarters of a mile off the coast when they realized their trouble. Almond had been trying to land the fish. Campbell was busy steering the boat into position, and Corea was taking pictures. They tried to start the engines, but couldn't. With the current and wind coming off the coast, Campbell said. "We went out like a rocket. We knew we were in for it. This happened just as it was getting dark. By morning, land was no longer visible."

They were to drift 500 miles northwestward. Air and sea rescue efforts failed to locate them.The ocean rocked the little boat with the sunken stern. The first five days it was too rough to bail. They could only hang on, and hope not to capsize. On the third day, Campbell proposed to Corea.

"Did you ask because you were frightened?" she asked, kidding him, the other day.

"What did I have to lose?" he answered, laughing. "No, really, I was very much in love."

But they desperately needed water.

"We had 12 days with no rain," Campbell said. "Under the blazing sun, we were getting to the point our kidneys were aching. We were getting weak, getting very weak. We were scared about the lack of water."

That's when they turned to blood: the blood of the seabirds that circled them, of turtles and sharks. They caught eight modest-sized sharks, shooting the largest - which Campbell described as about nine feet, 300 pounds - with a .38 caliber pistol they had managed to salvage. Food was never a problem, with fish, sharks and turtles. Corea tried blood only once; that was enough for her.

Campbell called the seabirds' blood foul. "The best was turtle blood," he said. "It was almost like a broth."

"I don't quite agree," said his wife, "I was sick the whole day."

By that time, the three had serious doubts about surviving. They wrote their wills. And on July 21, they began to pray.

Three days later, following more prayer - we thought this prayer was a good thing - it rained. The heavens just opened. We got 17 gallons of water. We were high on water, man."

Then, as long as they didn't encounter a shark they couldn't handle or a whale that would upset the boat or a storm that would capsize them, they had enough water for about three more weeks. It was a matter then of being found.

One ship came close but, Campbell said. "It reversed, came swinging down on us, seemed as if it were going to hit us, then took off." Finally, Campbell saw the freighter that would rescue them, the American Lancer, en route from New York to Long Beach, Cal. They were 110 miles off Puerto Madero, Mexico.

"A man named Victor Marquez was on watch on the bridge," said Campbell. "He heard something. It was us shouting. She started circling." Then it looked as if the ship were leaving."There she goes again," said Almond, disconsolately. "Then," said Campbell, "we saw action aboard the ship. Lights were going on. They were throwing heavy lines at us.

"When we got aboard, the captian said. "Heard you been out there three days," I said. "We're been out there 21 get him a shower and some food.'"

They took long showers and ate much ice cream; they all wanted ice cream.

And last Friday, in a Van Nuys wedding chapel. Campbell and Corea were married, Almond was best man.

Corea's mother, who lives in Los Angeles, missed the wedding. She had gone to Nicaragua where Corea said a mass was held for the three - a funeral mass.