Executive summary
On 16 August 2003, at about 1420, as the container ship "Spirit of Enterprise" crossed the Manukau Bar, it encountered several large swells, causing it to pitch heavily. The ship's rudder struck the seabed with sufficient force to fracture the rudderstock causing the loss of the rudder, thus disabling the ship.
Safety issues identified were:
· insufficient "real time" environmental information
· pre-accident cracking of the rudderstock
· possible pre-damage to the rudderstock from a previous grounding and the jamming of the flap actuating mechanism
· adequacy of the rudderstock size despite the high-strength steel design.
Safety recommendations were made to the Manager Marine Services of Ports of Auckland Limited and the Chief Executive Officer of Bureau Veritas classification society
Related Recommendations
Advise all member Classification Societies of this accident and that where a reduction in diameter was granted for rudderstocks made of high-strength steel, surveyors and ship operators should be aware of the possibility of load stress cracking. Vessels fitted with such rudderstocks should be inspected to check for such cracks.
Put in place an inspection regime to check for load stress cracks in rudderstocks made from high-strength steel of tensile strength exceeding 400 MPa or yield strength exceeding 200 MPa that were manufactured to comply with the 1996 rules.
Evaluate the information gained from the Taharoa wave rider buoy. If there is significant difference in the sea conditions between the Taharoa and Manukau or if the Taharoa wave rider buoy data is not available to POAL, he shall urgently take steps to place a wave rider buoy or other suitable measuring equipment close to the bar.
Provide accurate sea condition information to masters and pilots of ships transiting the Manukau bar. In the first instance he should endeavour to gain access to the data from the Taharoa wave rider buoy, either in real time or within one hour of its measurement.