Lloyd’s Register’s new container securing rules will allow box ship operators to carry more cargo
Starting in 2017, this has been a major project for the class society. Product owner for container securing Seb Brindley highlighted its importance. “Container securing rules directly affect the capacity of the ship and hence the return on investment that can be achieved, so it is an important consideration both when ordering a vessel and for ships in operation.”
LR has led the way for classing ultra large container ships (ULCS). This year alone, LR has 7.5M gt of ULCS delivered or on order. LR says this success is related to the container-carrying flexibility its rules can safely permit, which has a significant impact on the operability of ultra large container ships.
In 2017, LR released a major update to their container securing requirements, providing an advanced solution capable of reliably calculating the loads experienced by containers and loose fittings on board vessels. This is essential for external lashing arrangements, implemented on almost all ULCS. Mr Brindley comments “we acknowledge the significance and importance of vessel roll motion, particularly with regard to parametric rolling and synchronous rolling; one of the major causes of container loss.”
LR actively promotes integrating simple operational support tools to prevent incidents and in 2016 developed an operational guidance document for masters. Although this is not a class requirement, LR can provide this on a consultancy basis.
This year, LR launched new customised rules which can work with operators taking advantage of modern support systems, focusing on providing flexibility and simplicity without compromising safety. Operators can optimise carrying capacity for specific routes safely, offering better utilisation of their vessels as well as reducing the environmental impact per TEU.
The class society has developed an advanced non-linear solver that models twistlock separation and lashing bridge deformation. Mr Brindley explains “The key thing we have introduced is a revised method of determining the loads within containers and the lashing rods. It is a matrix solution, including all the key aspects that influence the distribution of forces within the container corner posts and the lashing rods.”
Mr Brindley adds “The non-linear behaviour of twistlocks significantly impacts the container stacks, especially for external lashing. When the ship rolls, the high side of the stack lifts and the twistlocks that tie the containers together do not engage until the twistlock locks in tension with the corner castings of the container. Until this happens there is no load transferred through the corner posts of the container but the load in the lashing rods can increase significantly.”
He continues “Compared with traditional linear solutions, modelling non-linear behaviour can make a big difference to the force distribution for many lashing arrangements; and with a better understanding of the force, distribution operators can carry more containers or load containers more flexibly without reducing the safety margin.”
This non-linear behaviour of container stacks has been recognised for many years, but until now, non-linear stack calculations have been too slow and it has not been practical for operation teams to consider this behaviour when planning ship loading. LR’s solver is now fast enough and is currently being used by operators of ULCS; both for planning and on board.
Having launched the rules in 2017, LR has been busy over the last two years talking with ship operators, lashing manufacturers and software developers.
Mr Brindley says “Because of the complexity of the non-linear solution we now provide a software solver designed to integrate with third-party software. The major onboard software companies have integrated our solver into their software tools for use on board and for planning, as have several lashing manufacturers.”
Software companies and lashing manufacturers that have integrated or are integrating the solver into their container securing software are:
Mr Brindley explains the process “We provide software developers with the solver and documentation but find that most require some support through the process. Typically, it takes a developer 2-3 days to set up the data structures and integrate with the solver.”
Having completed integration, updating the software to reflect future rule changes will be straight forward – simply a case of swapping the solver. Having the container securing calculations coded by LR also provides a high level of confidence that the calculations are correct, although LR has no plans to change the process for class approval of onboard container securing calculators at this time. Mr Brindley also confirmed that LR does not charge software developers to issue the solver for use on board.
An example of customer engagement over the new lashing rules is COSCON. The Chinese liner company has applied the new non-linear rules to three of its six new 21,000-TEU ships, delivered at the end of 2018.
Mr Brindley explains “We visited COSCON in Shanghai to discuss the integration of our new rules and the performance of their newly delivered vessels.”
“We had a discussion with COSCON and they highlighted some operating difficulties they were facing on certain routes. This allowed us to work closely with them, developing a tailored solution using our advanced solver and expertise.”
COSCON will now use LR’s rules for its remaining three 21,000-TEU ships, which are not LR-classed. “This is significant for us and for them,” Mr Brindley says.
COSCON marine operating centre manager Captain Xia Shao Sheng tells Container Shipping & Trade, “Initially, using the 2018 rules we felt the carrying capacity did not match our requirements and the calculation speeds were slow making it hard to plan the vessel’s loading. We raised this with LR and overnight the class society provided a solution implementing the latest 2019 rules and arranged for a new release of software to support our container planning.
“LR’s 2019 container stack calculations are based on an advanced and fully validated approach so we have a high degree of confidence in the outcome, especially for assessing our world-class ultra large container ships. We would like to continue working closely with LR based on the flexibility the rules safely permit and the stacks we can load.”
Snapshot CV: Seb Brindley (Lloyd’s Register)
Seb Brindley joined Lloyd’s Register in 2015 as lead specialist for structural analysis in the marine and offshore division. He is part of LR’s marine technology and engineering services department in Southampton, working in LR’s consulting and rule development division. He currently develops structural procedures and rules for LR, while also assessing complex problems for LR’s clients focusing on strength and fatigue.
Previously, Mr Brindley was headhunted by Samsung Heavy Industries in 2013 to work in their European Procurement Centre, London to co-ordinate and manage European topside packages from design to delivery. Before this, he was part of ClassNK’s Research Institute, Chiba, Japan in 2009, and worked extensively on international and domestic projects with shipyards and universities, as well as internal projects, developing guidelines and regulations.
Mr Brindley graduated from Strathclyde University in 2009 with an MEng with distinction in naval architecture and ocean engineering.