The first case of the latest edition of UK MAIB Safety Digest includes lessons learned regarding a maritime accident where significant starboard list caused cargo to shift, resulting in leak and subsequently flooding.
Specifically, a 50,000gt vehicle carrier had completed loading and was proceeding to sea. As the ship turned to port to follow the navigable channel around a sandbank, it developed a significant starboard list. The list increased to in excess of 40º, causing the ship to lose steerage and propulsion and to drift onto the sandbank.
The list caused cargo to shift, resulting in breaches to the ship’s hull and consequent flooding. However, all crew were safely evacuated and there was no resulting pollution.
Lessons Learned
1. The ship heeled heavily to starboard while turning as a result of having departed port with inadequate stability. The following factors contributed to its lack of stability:
• The ship’s normal operating cycle had been changed, but the cargo loading plan had not been adjusted. Consequently, the upper vehicle decks were full while the lower vehicle decks were lightly loaded.
• The change in operating cycle meant that the ship was low on bunker fuel oil, which was stored low down in the ship.
• The estimated weight of many items of loaded cargo used in stability calculations was less than their actual weight.
• No allowance was made for the vertical centre of gravity of the loaded cargo being above deck level.
• The distribution of ballast on board the ship was not accurately known and bore no resemblance to reality
2. It would have been possible to increase stability by loading additional ballast low down in the ship, but the shortcoming in stability had not been identified prior to the ship’s departure. Assessing a ship has adequate stability for its intended voyage on completion of cargo operations and before it sails is a fundamental principle of seamanship that must not be neglected.
3. A loading computer is an effective and useful tool for calculating a ship’s stability. However, its output can only be as accurate as the information entered into it. The value of establishing before departure that a ship has a suitable margin of stability for the intended voyage had eroded over time such that unsafe practices relating to cargo loading and ballast monitoring had become the norm.
Source: UK MAIB
