The 22-year-old navigator of the Coast Guard cutter Cuyahoga told a board of inquiry yesterday that a surprise course change and a preoccupation with navigational bearings on the bridge led to the vessel's fatal collision with an Argentinean freighter.

A second crewman also testified yesterday that an inexperienced Indonesian trainee was assigned to the ship's surface radar when the collision occurred and that he sometimes "had a hard time understanding what he said."

The navigator, petty officer Randy Rose, said that crewmen assigned to take bearings may have been overly concerned with the dangers of passing Smith Point on the left near the Potomac River mouth and not with the congested shipping lanes to the right.

Rose said yesterday that he saw the two ships in a "dangerous" situation and that a last-minute order from the ship's commanding officer. Chief Warrant Officer Donald K. Robinson, 46, "wasn't a course I expected to turn to."

Moments later the freighter, the Santa Cruz II, rammed the cutter's right side, ripping through its steel hull and dragging it several hundred feet backward. The Cuyahoga sank within minutes and 11 men aboard died.

Robinson, who has been present in the hearing room this week, has declined to testify to the board. His attorney said last night that Robinson, who has been told he is a suspect in the probe, has decided not to give further statements to the investigators. Such statements could be used in a later court-martial.

Testimony yesterday by Rose and two other crewmen added to the picture drawn this week of the series of chaotic events aboard the training vessel that preceded the horror-filled collision. For some of the crewmen, their first watch on their first cruise was also their last.

Shortly before the accident, Rose testified, trainees on the watch team were busy "taking bearings on Smith Point," adding that no bearing takers were located on the right or starboard side of the ship's bridge.

Rose said, however, that Robinson was standing inside the doorway of the bridge's starboard wing. The collision occurred minutes after the Cuyahoga had made its left turn and was heading across the busy shipping lanes into the mouth of the Potomac River where it was to anchor for the night.

Rose also testified that the ship's compass was off by as much as 10 degrees, and added, "I couldn't keep an accurate track of where the ship was every minute."

According to charts of the area of the Cheasapeake Bay, vessels are warned to use extra caution when crossing the congested shipping lanes. The lawyer for the Santa Cruz's American pilot called the area "a bottleneck" which must accommodate all intercoastal north and southbound sea traffic.

One of the Cuyahoga survivors described looking at the ship's radar coverage of the Chesapeake Bay as "confusing because it looks like you are watching the funnies or cartoons on television on Saturdays morning."

The Cuyahoga, referred to as a "floating classroom" during yesterday's proceedings, was used to give officer candidates from Yorktown, Va., on-the-job training.

Robinson remained tight-lipped during yesterday's hearing but broke into a smile when Kevin Henderson, a member of the team on watch on the bridge, told the investigator that he often sat in the captain's chair. "We had an agreement," Henderson said, looking over at his former commanding officer. "I would warm it up for him."

Whether the Coast Guard cutter had strayed off its course while making the turn into the mouth of the Potomac River was unclear. Rose testified that on an earlier cruise, the Cuyahoga had come dangerously close to Smith Point and had modified its course northward.

Although the ship's compass had malfunctioned prior to last week's cruise, the crew members testified it had been repaired.

Fiftenn minutes before the collision, Henderson, 20 testified, he was asked by Robinson to get a "fix" on the contacts that had been spotted by the ship's lookout. Henderson said he went to the radar man - an inexperienced Indonesian crewman - and was told that the target was 4,700 yards northeast of the Cuyahoga.

"I went back and told the captain and that was it," said Henderson.

Henderson and 17-year-old Seaman Michael Myers both said they spotted a green light belonging to the Santa Cruz off their ship's starboard (right) bow moments before the collision. Both men also testified that the huge freighter turned into the Coast Guard cutter.

But according to Rose, the collision occurred when the Coast Guard cutter failed to yield way to the freighter.

Rose indicated that the collision might have been avoided at the last moment had the ship turned to the right of the freighter instead of turning left into the oncoming freighter's path.