Page 22: of Maritime Reporter Magazine (April 2011)

22 Maritime Reporter & Engineering News

COLUMN EYE ON DESIGN

Cargo Securing ... in need of shoring up?

Supported by the Dutch government, MARIN initiated the Lashing@Sea Joint Industry Project to obtain a snapshot of current cargo securing practices as a base for ongoing and future research and innovation.

Securing cargo has been a concern for as long as ships have sailed. And although technology has moved on, it is still a concern today. More and more cargo is being put on bigger and bigger ships and in turn, the time available to secure each unit is decreasing. The diver- sity of the issues surrounding lashing is illustrated by the fact that some shipping sectors are seeking reduc- tions in lashing requirements, while other sectors are struggling to explain incidents with supposedly safe se- tups. Lashing@Sea therefore, focused on identifying reasons for unexplained cargo incidents involving mul- tiple, collapsed container stacks and on the other hand, on reducing lashing in the RoRO and heavy lift trans- port sectors. As part of the project, interviews, crew questionnaires, incident reviews and measurement cam- paigns on five ships took place. In addition, model tests on a dynamic “shaker” test platform were carried out to investigate cargo-securing dynamics under controlled circumstances. Operational feedback and a review of current practice showed that there are often mismatches between the “as designed” and “as loaded” cargo con- figuration. The reliability of cargo weights, cargo loca- tion, the operational stability of the vessel and additional accelerations because of hull flexibility, were particu- larly found to introduce uncertainties. Measurements and numerical analysis showed that none of these effects alone will exceed safety margins but unfortunate com- binations may trigger dynamic interactions that can damage securing and even lead to the collapse of multi- ple container stacks.

RECOMMENDATIONS

The findings were forwarded to IACS and the IMO. A proposal for guidance on dealing with weather-depen- dent lashing was also put forward. Further recommen- dations included the need to increase the reliability of cargo stows by measuring and checking weights and to assist crews with handling extreme weather and nonlin- ear ship responses. Operator guidance to prevent hull deformation, fatigue and cargo damage, is addressed in the new TALLSHIP JIP. Lashing@Sea comprises 23 participants Including ship operators, class societies, flag states, lashing gear manufacturers, training organi- sations and onboard systems suppliers.

About the Author

Jos Koning is senior project manager Trials & Monitoring at MARIN, the Maritime Re- search Institute Netherlands.

Email: [email protected]