Green water MARIN study reveals: Feeder ships sailing by the Dutch Wadden Islands are at risk of losing deck containers
Conference/JournalMARIN Report 135
Date20 Apr 2023
With the accident of the Ultra Large Container Ship “MSC Zoë” in January 2019, during which 342 containers were lost overboard a few miles off the Dutch Wadden Islands, the problem of recurring container losses and the associated pollution in an area labelled as “Particularly Sensitive Sea Area” regained public attention.
While the initial focus was on the larger vessels, more recent container losses from the 169 m “OOCL Rauma” and the 170 m “Baltic Tern” - representing five containers in both cases - showed that feeder ships are also at risk. With a relatively low freeboard, feeder ships are more vulnerable to green water than larger vessels. Therefore, the Dutch Ministry of Infrastructure and Water Management asked MARIN to conduct a study on the risk of green water exposure for feeder ships, in view of refining the recommendations sent by the Netherlands Coastguard to ships in the area.
Senior Project Manager
Changing course mitigates risks
Model tests showed that the largest wave loads occur in high, steep waves from the beam that break against the ship’s side shell and side containers. While the wave height at which green water loads on containers are observed depends on the amount of freeboard, loads are already observed on the lowest containers on the deck during the tests with a significant wave height of 1.8 m.
Water depth was found to have an important effect on green water loads
High speed green water impact in 4.5 m beam waves
Ships of 100 - 200 m now advised to alter course and take appropriate measures to avoid these incidents.