An industry collaboration between Waves Group, Britannia P&I Club and Lloyd’s Register has been published with a view to providing crews with improved operational guidance
The writers noted that the frequency of container losses at sea had been a problematic and very costly issue for the industry over the years. The World Shipping Council 2019 report on the matter recorded an annual average loss of 1,382 containers.
While these figures remained small in comparison to the number of containers being transported annually, container stack collapses still posed a significant risk to the industry, both in terms of claims and the potential environmental impacts, the writers said.
Even though there have been advances in the procedures and standards for the loading, securing and carriage of containers, stack collapses were still happening, with each winter season raising the prospect of more to come.
A collapse of on-deck container stacks posed a serious threat to the safety of the crew and the ship. Depending on the contents it could also have a significant impact on the environment, with clean-up and recovery costs significantly increasing the value of claims and the associated impacts on reputations.
The question of what causes a stack collapse, how it can be prevented, and what to do when there is a collapse, is the subject of ongoing research and consideration by experts within the industry. A number of factors might contribute to a collapse, including:
- the design of the vessel,
- its speed and heading,
- its stability characteristics,
- the sea conditions,
- the stowage, securing methods and equipment,
- and the phenomena known as parametric and synchronous rolling.
In adverse weather conditions, vessels can encounter excessive rolling and pitching which can cause a ship to roll at extreme angles of up to 30 degrees or more, potentially leading to a stack collapse and the loss of containers. When this occurs, swift action has to be taken. A simple adjustment in the speed and course of the vessel might be enough to remedy the situation or prevent a dangerous incident. However, having the right information to hand when such situations arise is critical.
Waves Group have worked with the Britannia P&I Club and Lloyd’s Register to develop an on-board guidance to assist the bridge team in identifying such conditions that might lead to parametric or synchronous rolling and how to take the appropriate actions to mitigate these risks.
The operational guidance (see link at end) covers container vessels from 3,000 up to 23,000 teu in size.
The guidance applies the writers’ collective experience of containership operations and the investigation of numerous stack collapses.