Power failure leads to grounding

Electronic charts are a boon for navigators – but so are bridge windows. Latest Mars Report refers to an incident in which a Master seduced by the screen found that the electronic picture can be misleading. The ship was about to enter a lock when it suffered a voltage drop and the engine-room team initiated blackout procedure. The Master put the engine astern to abort the lock entry and began a 180° starboard turn to head south away from land.

The Incident

A bulk carrier was approaching a lock entrance in daytime and with good visibility. Two persons were in the wheelhouse: the Master was at the con and a helmsman was at the wheel. The Master had previously instructed the Officer of the Watch (OOW) to go on deck in preparation for the lock transit. As they approached the lock outer piers, at a speed of about nine knots, the Master called the engine room (ER) and requested the bow thruster. Once the power to the bow thruster was transferred to the bridge, it ran for approximately one minute without being used, at which point its circuit breaker tripped. 

The circuit breaker was reset and closed by ER staff and the bow thruster restarted; the voltage in the electric distribution system dropped and the No.3 generator main circuit breaker tripped. However, the No.1 generator continued powering the main switchboard. The main engine continued to operate and the lights remained on throughout the vessel. 

The drop in voltage set off a number of power failure alarms on the bridge, including both gyrocompasses. The radars defaulted to standby mode and two of the three rudder angle indicators on the bridge were disabled. The Master put the engine astern and initiated a starboard turn to abort entry to the lock canal entrance.

For five minutes, while engine room staff repeatedly undertook the blackout procedure, the power failure alarms on the bridge sounded three more times following their initial activation. The bridge team did not know why the alarms were repeatedly activating. The second officer arrived on the bridge and began silencing and resetting the alarms, as per the Master’s orders. Meanwhile, the Master took measures to increase the vessel’s rate of turn to starboard. He was monitoring the vessel’s turn on the Electronic Chart Precise Integrated Navigation System (ECPINS), but without confirming through visual navigation. He then ordered the helmsman to steer 180 degrees gyro (°G) so that the vessel would proceed on a southerly course, away from land. 

A few minutes later, the Master looked at the ECPINS slave monitor and noticed that the vessel’s course made good was easterly, but that the vessel-shaped marker that indicates the heading was pointing southerly. He requested the magnetic heading from the helmsman, who reported it to be 111° magnetic (M). The Master looked outside and saw that the shoreline was on the vessel’s port side, instead of on its stern. He immediately ordered the helm hard to starboard to correct the vessel’s course and increased the propeller pitch to get more power ahead. The vessel began turning to starboard but, moments later, the hull touched bottom and the vessel ran aground 1.5nm southeast of the lock outer piers (number 7 in diagram).

The official report found, among other things:

• A number of power failure alarms on the bridge created a situation that resembled a blackout and was interpreted as such.
• Engineers responded to the developing situation by applying the vessel’s blackout procedure twice, which caused additional power interruptions to the bridge; however, the engineers were unaware that these actions were having this effect.
• The power interruptions on the bridge, combined with the vessel’s turn to starboard, caused the gyrocompass to become misaligned.
• Following the power interruptions the Master was (unknowingly) using inaccurate data from the ECPINS. Additionally, he was not using all available bridge resources to monitor the vessel’s progress for nearly 15 minutes before the grounding.

Source: Mars Reports/ The Nautical Institute