Over reliance on the accuracy of Global Positioning System (GPS) derived positions by a watchkeeper contributed to the grounding of the 35 m adventure cruise vessel True North at about 2300 on 7 August 2004, according to an Australian Transport Safety Bureau (ATSB) investigation report released today.
The ATSB report into the grounding of True North in the approach passage to St. George Basin, in Western Australia's Kimberley region, states that the vessel grounded on or near Strong Tide Point after a voyage from Prince Frederick Harbour. On board at the time of the grounding were 26 passengers and 12 crew. No pollution resulted from the grounding.
The report concludes that the vessel grounded while being navigated by an auto helm unit and an Electronic Chart System (ECS) receiving position information from GPS satellites. The GPS derived positions plotted on the ECS differed from the vessels true position by about 300 m. This error was possibly caused by a combination of factors, including GPS system inaccuracy, geodetic datum ambiguity, and a possible recent change in the ECS operating systems computer or GPS receiver parameters.
The report finds that the vessel's master, who was alone in True Norths wheelhouse at the time of the grounding, was probably suffering from some effects of fatigue as a result of his work routine. The master did not adequately cross check the GPS positions on the ECS by other navigational means, nor did he maintain an adequate visual or radar check to ensure the vessel remained in safe water.
The report also concludes that there were deficiencies in the procedures which dealt with the mustering of passengers in the event of an emergency.
Copies of the report ( Marine Safety Investigation Report 205) can be downloaded from the website, or obtained from the ATSB by telephoning 1800 020 616.