2011X03 Aground, Approaches to Melbourne, Australia
Official Report No. 7011
After an incident a lot of comment is often generated about poorly maintained old ships, lack of competence, lack of training or inability to communicate properly. In this case, which has been investigated by the Australian Department of Transport and Communications, we have the complete reverse - a vessel built in 1989 as the first of a new generation, highly automated with advanced electronic systems not found on most commercial ships and officers given special training to operate the vessel. In spite of all this, the vessel went aground in the approaches to Melbourne. It is a classic example of how much reliance can be placed on technology.
The Ship
The ship is designed to operate with four watchkeeping officers who are dual disciplined and have both nautical and engineering responsibilities. In theory they work a ten hour day, spending six hours on the bridge, two hours in the engine room and two hours working on other responsibilities. The whole crew work together for a considerable period of time and the four officers rotate responsibilities on a voyage basis. The bridge is designed for continuous one-man operation, including during port entry and berthing operations, with control stations (engine, steering and communications) situated on each wing and in the wheelhouse. The ship is equipped with a computerised automatic steering system which can be adjusted for maximum rudder angle setting, rate of turn, radius of turn, and for either economy (open sea) or precision (entering/leaving port) steering accuracy. The required course is input by manual depression and rotation of the control knob, which is rotated until the required course appears on the "set course" digital readout. The actual ship's heading is shown in the digital "heading" display. When altering course, one degree of course alteration requires about 15 degrees rotation of the control knob. The computer is programmed to apply rudder movements according to pre-set parameters to bring the ship on to the required course. If the ship fails to respond for any reason, the computer will apply more rudder. The computer can be over-ridden by operating the auto-tiller which gives direct manual control. When in auto-tiller mode the "set course" changes to show actual heading.
For arrival off a port, the normal bridge manning comprises of the master, the watch officer and one mechanic, the latter preparing the pilot ladder, the anchors, hoisting flags, meeting the pilot and such other duties as required. When the crew go to mooring stations, the watch officer proceeds to the fo'c'sle and the mechanic to the poop, leaving just the master and the pilot on the bridge.
Although the ship is fitted with a manual steering position on the centre line, at least one of the masters assigned to the ship had used automatic steering from berth to berth, including transits of the Suez Canal, right from the maiden voyage. The only exception being manoeuvring alongside, when the master controlled the steering from the bridge wing. The ship's two electric steering motors can be operated in parallel or independently. Only the starboard motor is connected to the emergency power system but both motors can be switched on and off from the bridge.
Sequence of events
On this particular voyage, in addition to the design crew number, there were supplementary crew on board in the form of a chief engineer, a second (reefer specialist) engineer and an apprentice. However, the four "standard" officers maintained their normal areas of responsibilities and watchkeeping duties. For port entry the apprentice was stationed on the bridge and, as part of his training, he manned the command station and operated the engine and steering controls, monitored by the watch officer. The apprentice had performed this duty at the previous ports of this voyage. The day before arrival at Melbourne the master had decided that the apprentice would act as watch officer for arrival and be monitored by the watch officer and the master.
The master arrived on the bridge to join the watch officer, apprentice and mechanic at 0800. The apprentice calculated when the ship would need to start reducing speed to pick up the pilot. At 0900 he contacted the signal station to confirm the ETA. As soon as the ship had reduced to manoeuvring speed, the apprentice carried out the pre-arrival checks and tests as detailed in the USCG Check List "S2". This included stopping the engine and testing astern movement and testing the manual and remote steering systems. The steering motor in operation was #2 (port).
On taking over the con, the pilot saw that the ship was heading 0650 and ordered a course to bring the ship on the leads for passing through Port Phillip Heads. Monitored by the watch officer, the apprentice, having repeated the order, made the adjustments to the autopilot. Speed was increased to "full manoeuvring" - 15.5 knots. The pilot calculated that an outward bound deep draught bulker would pass through the dredged "cut" before they arrived in that area. Various course alterations were made en route and the pilot, although he had been reluctant to use it, judged that the vessel responded well in automatic steering mode.
At 1030 the engine speed was increased to combat the ebb tide. The ship was kept to the south side of the channel in preparation for passing the outward bound vessel. The master and watch officer were both in a position to monitor the apprentice at the control station. The outward bound ship passed on the port side shortly after 1058. As the line of buoys opened, the pilot ordered a course of 1050 to pass between buoys 11 and 12. With the ship on the new course, the pilot looked astern and noted from the wake that the ship was yawing about 2 degrees. Looking ahead, he realised that the course would take the vessel close to #14 buoy on the north side of the channel and, as the ship was passing #11 he ordered a course adjustment to 1070. The apprentice repeated the new course required and, monitored by the watch officer, applied a two degree adjustment to the auto-pilot. He then watched the ship's bow swinging across the shore line ahead.
Everyone on the bridge realised that the ship was swinging too rapidly to starboard. The apprentice put the auto-tiller to port five and then port ten, cancelling the over-ride alarm as he did so. Both the master and the pilot ordered "hard to port", the master leaning past the apprentice and performing the operation himself, noting that the rudder angle indicator showed starboard 15. The apprentice noticed that the digital course indicator showed 110 at about this time. The master then ordered the mechanic to the manual steering position, ordered him to put the wheel hard to port and switched over from autopilot to manual. The swing to starboard slowed, then stopped, by which time the South Channel Pile beacon was fine on the port bow. The ship then started to swing back to port. Fearing that the stern would swing into the bank, and so possibly result in damage to the rudder and propeller, both the master and the pilot ordered "stop engines" and "midships the wheel", and then "full astern". From the data-logger record, the time for the stop command was 1102. When the ship had swung round to a heading of about 1110, it grounded on the starboard bank of the cut, heeling over to port as it did so. The ship then came to a stop between the South Channel Pile Beacon and #13 buoy, on a heading of 1090.
The pilot advised the signal station that the vessel was aground and then efforts were made to refloat the vessel using the main engine and the bow thruster. This was soon aborted due to concern about causing damage to the starboard bilge keel area if the ship slid sideways, the tide was falling and tug assistance deemed necessary. The indicator panel showed no sign of any ingress of water and some crew were deployed taking soundings around the ship.
Two tugs were requested, together with a survey chart of the area, a second pilot and a salvage expert. The tugs were made fast, one forward and the other on the port quarter at 2108. At 2109 the engine was put to "half astern", then "full astern" and the bow thruster on full port thrust. After 10 minutes, by which time the after tug had attained full power, the bow thruster was given a full thrust kick to starboard. After about another two minutes the ship started to move slowly to starboard and then slowly astern. When the astern movement was steady, the bow thruster was put on full port thrust and the ship moved off the bank, floating free at 2126, maintaining the same list.
The tugs were released at 2213 and the ship continued its passage to West Swanson Dock. Underwater inspection of the ship's hull indicated that no structural damage had occurred as a result of the grounding, only minor scraping on the paint work. Thorough testing of the steering gear system and the autopilot system by manufacturers' servicing agents while the ship was in Swanson Dock indicated that both systems were functioning normally.
Comment
The investigators looked at several aspects including human input error. They decided that if the apprentice had input 117 instead of 107 the computer would have applied 20 degrees or more rudder. Whilst this cannot be totally discounted, the statements of the ship's staff do not support this as the cause. Momentary systems failure was also ruled out. The electronic equipment on the vessel was more like aircraft control equipment and therefore liable to electrical radiation interference but this was considered unlikely. Hydrodynamic forces were also considered, such as those caused by the recent passage of the deep draught outward bulker and the effects of squat. The ship was travelling at speed and had a relatively small underkeel clearance which would have had a marked adverse effect on the manoeuvrability.
Conclusions
The vessel grounded as a result of a rapid sheer to starboard brought about by the rudder moving to starboard 20 degrees. It is considered that:
Although an autopilot human input error is the most straightforward and simplest explanation for the movement of the rudder to starboard 20 and cannot be totally discounted, such an error was unlikely.
A momentary systems failure, either of the autopilot or the steering gear, was unlikely.
Electrical radiation interference of the electronic control systems, from an outside source, was unlikely.
Possibly no conceivable malfunction occurred, instead the movement of the rudder to starboard 20 was the response of the autopilot, under the programmed settings, to that particular set of circumstances.
The speed of the vessel on entering the cut was around 18.5 knots.
The effect of squat reduced the underkeel clearance as the ship passed between buoys 11 and 12 to 4.78m. As the ship sheered away from the centre line, this would have been reduced to about 2.75m, which would have had an adverse effect on the ship's manoeuvrability.
Those on the bridge acted quickly and correctly, but were unable to prevent the grounding.
At the speed at which the vessel was travelling, once a sheer commenced, grounding was unavoidable.
Although regulation 339 of the Port of Melbourne Authority (Amendment) Regulations 1988 is no longer considered appropriate, had the vessel been proceeding at much reduced speed for the passage through the dredged cut, the lateral movement to starboard would not have been so great and, therefore, the grounding would have been less likely to happen.
The movement of the rudder to starboard 20, the resultant sheer, and hence the grounding, would most probably not have occurred had the steering been conducted manually.