93065 Grounding of QE2

The investigation into an incident on the QUEEN ELIZABETH 2 by the British Marine Accident Investigation Branch reached the following conclusions:

The QE2 grounded twice in quick succession at approximately 2158 LMT on 7 August 1992. Initially at position Latitude 410 22,.2N, Longitude 0700 57,.5W. The second contact was at a position 0.1, further West. The maximum depth of water at the two positions was 35.0 feet and 34.2 feet respectively. The charts in use did not show the correct depths below chart datum at the grounding positions.

It is assumed that the stationary forward and after draughts of the vessel were 32.3 feet and 31.3 feet respectively. On the assumption that no change in draught was caused by the effect of the prevailing weather conditions, it is apparent that the effect of squat on the vessel caused the bow to sink by at least 2.7 feet. The extent of the resultant damage suggests that on grounding, the vessel was trimmed by the head. The Master had expected squat of 1 to 1.5 feet, with change of trim by the stern. It is clear that he underestimated the magnitude of squat upon his vessel in the prevailing circumstances.
Tidal data had previously been calculated for Martha's Vineyard using tabulated predictions for Vineyard Haven. With reference to such data, the Master overestimated the height of tide at the vessel for the time of grounding , at about two feet above datum. Prior calculation of the predicted height of tide at Gay Head for the time of transit would have provided a good indication of the predicted height of tide at the vessel on passing the NA Buoy at which point the Master expected to encounter the least sounding for the departure passage. This would have given a height above datum of about half a foot.

The immediate causes of the accident were, therefore, the presence of significantly shallower depths than those charted, together with an overestimation of the height of tide and an underestimation of the effect of squat.

The rocks on which the QE2 grounded are located in an area between adjacent sounding lines established by the US Coast and Geodetic Survey in 1939 which were not indicated on either the NOAA or BA charts in use aboard the vessel. Within 0.5 mile of the rocks, the survey established a least depth of 39 feet below chart datum and that is the least charted sounding shown within 0.5 mile of the grounding position on chart 2890. Charts 2456 and 2890 indicate that the charted information presented is taken from recent US Government charts. However, they do not indicate the dates of the survey upon which the US Government charts are based. In the absence of such survey data, the Master was restricted in his ability to assess the reliability of the charts.

It is considered that the Master was deceived by the appearance of the charts in use and placed undue reliance upon the information presented. It is also considered probable that if the correct depths had appeared on the chart, the need to avoid the area south of Sow and Pigs Reef would have been recognised by both the Master and the Pilot and a different course, to keep clear of it, would have been set from the NA buoy.

Prior to departure, the Pilot was not consulted with respect to the passage plan to be followed after passing the NA Buoy. Such consultation would have revealed the differences between the vessel's intended passage compared with that of the pilot and a single plan could then have been agreed and understood by the Pilot and the Bridge Team before departure. The vessel would not have transited the grounding positions had either of the original passage plans been strictly followed. Neither the Master, Pilot nor the 2/O appreciated that the revised track passed in close proximity to a charted sounding of 6 fathoms 3 feet.

The position of the vessel was determined at regular intervals by satisfactory means and an estimated position was projected ahead on each occasion. Prudent use was made of the larger scale NOAA charts for reference purposes. However, it is evident that the progress of the vessel was not continually monitored during the 6 minute interval between fixes. After passing the NA Buoy at 2144, a deviation from the vessel's intended track remained unappreciated until the position of the vessel was fixed at 2148. The magnitude of the deviation was enhanced by the high speed of the vessel. Radar parallel indexing techniques would have provided a simple and effective means for continually monitoring the vessel's position.

In determining that an increase of speed to 25 knots was safe, it is considered that the Master, although having confirmed the Pilot's agreement, omitted to take full account of the effect of squat, the possible unreliability of the charted information and the predicted height of tide throughout the departure passage.

Merchant Shipping Notice M854 stresses the need for close co-operation between the ship's Bridge Team and the Pilot, for account to be taken of squat in assessing safe speed; and for the vessel's progress to be continuously monitored. It refers specifically to the advantages of parallel indexing. While in many respects much effort was put into following good practice, in these particular matters it is considered that the guidance given in the Notice was not fully heeded.

The ingress of water to the vessel due to the grounding was contained within the deep and double bottom tanks and caused no adverse effect on stability. Key members of the ship's complement acted swiftly in assessing the extent of resultant damage and steps were satisfactorily taken to monitor any further ingress of water.

Appropriate use was made of damage control equipment provided on board the vessel. Flood water was pumped overboard under controlled conditions with a USCG anti-pollution boom positioned around the vessel. There was no oil pollution of any significance. There were no resultant injuries to personnel.

It is recommend that the UK Hydrographic Office should, where applicable, endeavour to provide charted information relating to dates and coverage areas of surveys conducted by other national authorities upon which a particular Admiralty chart is based.

It is also recommend that the Marine Directorate should provide further guidance on squat, so that its effect on a particular vessel, when operating under a range of anticipated circumstances and conditions, may be reasonably estimated in cases where no specific data based on manoeuvring trials or computer simulation is available.