The July 2006 heeling of the cruise ship Crown Princess was caused by a bridge officer’s steering mistake after the captain adjusted the trackpilot’s rudder limit improperly, the National Transportation Safety Board said.
As a result of the accident, the NTSB is urging better training in integrated navigation systems and wants manufacturers to compile data on errors in their use.
NTSB investigators said 298 passengers and crew were injured when the 952-foot cruise ship rolled an estimated 24Â° to starboard one hour after departing Port Canaveral, Fla.
Trouble began when the captain of the Bermuda-flagged cruise ship accelerated the vessel to almost full speed -20 knots – while still in waters that were less than twice the ship’s draft.
That’s because the captain heard bad weather was developing off Cape Hatteras and wanted to try to beat it, he told the NTSB. Crown Princess draft is 29 feet, and the waters off Florida are only 16 to 26 feet deeper than that.
“What was unusual in this case was the ship was going a relatively high speed for that shallow water,” said Jack Spencer, director of the NTSB’s Office of Marine Safety. “The maneuverability of the ship was a little unpredictable.”
Indeed, the Princess Cruises vessel began deviating from its set heading. The captain and staff captain then adjusted the trackpilot’s rudder limit inappropriately, allowing it to turn too far, the NTSB said. At the same time, they failed to adjust an already inappropriate rudder economy setting, which was exacerbating the course deviations.
After the captains made their adjustment, they should have stayed on the bridge to gauge the ship’s reaction, the NTSB said. Instead, the captains transferred the conn to the second officer and went below. The second officer had 10 years of experience.
With the second officer as the senior watch officer on the bridge, Crown Princess began an unexpected turn to port. The second officer disengaged the automatic steering mode of the vessel’s integrated navigation system and took manual control of Crown Princess’ steering â€” a transfer he had never done before.
According to a transcript of his statement to investigators, the second officer said the severe heeling was “my mistake.” He said he became “a bit nervous” when the ship started going off course. He then turned the vessel to port when he meant to turn to starboard.
“I just got on the wheel and the ship was going to port, and I knew I had to go to starboard, and I turned the vessel and I was concentrating so much on the rudder orders, I just â€” I put the wheel the wrong way,” the second officer told the investigators.
The proper reaction should have been to slow the ship’s speed and bring the rudder to midships, Spencer said. Instead, the flustered second officer turned the wheel from port to starboard several times, at angles varying from an estimated 10Â° to 45Â°.
“As the second officer turned the wheel from side to side, his turning of the wheel was a lot faster than the rudder could respond,” Spencer said. “So for a time â€” maybe 40 seconds â€” the rudder was stuck over on the port side, and that’s what led to such a severe angle of heel.”
The second officer testified that he was well rested that day. However, his mother recently had been diagnosed with a brain tumor. He had quarreled with his mother during a recent vacation at home.
“We believe he was under a certain amount of high stress that could have affected his behavior,” said Tom Roth-Roffy, the NTSB’s investigator in charge.
Crown Princess was nearing the end of a nine-day Caribbean voyage with 3,100 passengers and 1,200 crew. Weather and visibility were good, and seas were calm. The NTSB ruled out equipment malfunction after running sea tests on the very same course departing Port Canaveral.
“The system performed properly,” Roth-Roffy said. “We couldn’t find any evidence that the steering system or the autopilot malfunctioned. The rudder position followed the rudder command.”
In response to the Crown Princess accident, the NTSB in January 2008 issued safety recommendations. The agency urged the Coast Guard to propose that the International Maritime Organization make training in integrated navigation systems and integrated bridge systems mandatory for watch keepers. It asks the Coast Guard to propose to the IMO that voyage data recorders be required to keep track of heel angles through the complete range of possible values.
The NTSB recommended that Cruise Line International Association ask its members voluntarily to provide training in integrated navigation system operation to crew who have watch-keeping duties â€” and include a proficiency requirement. The agency wants CLIA to inform its members about the circumstances of the Crown Princess heeling and urge them to teach crews about vessel performance at high speeds in shallow water.
The NTSB recommends that equipment manufacturers SAM Electronic and Sperry Marine develop a system of gathering data on errors and potential problems in the use of integrated navigation systems and integrated bridge systems. The information should then be used in new system design and crew training.
The tilt of Crown Princess serves as a reminder to mariners that inattention to seemingly small details can cascade into big problems.
“There were a few things that could have been done better; perhaps going a little slower in shallow water, or perhaps adjusting the INS differential (rudder limit), or perhaps not going down below as the captains did,” Spencer said.