Commentary: Overweight boxes and ‘minimum water’
Some of the most startling images in shipping publications this summer were those of the MOL Comfort, a containership that split in half during a storm on June 17 off the coast of Yemen.
The crew escaped unharmed, but both halves eventually sank, the fore section after catching fire. The casualty is confounding because the ship was only five years old, and built and operated by what are generally considered to be first rate companies—Misubishi Heavy Industries and MOL, respectively.
We spoke about the casualty to Steven E. Werse, a shipmaster of 20 years, secretary-treasurer of the Masters, Mates and Pilots union, and an adjunct professor at the State University of New York Maritime College. He said he could do nothing but speculate about the probable cause of the accident.
MOL has promised a thorough investigation that includes experts from the classification societies Nippon Kaiji Kyokai (Class NK) and Lloyds Register, but of course their job is complicated with both halves of the ship in Davy Jones’ locker. In August, Class NK had determined damage leading to the loss of the MOL Comfort “did not originate from the vessel’s upper deck area or hatch side coaming” and it is strengthening sister ships.
Werse said how a ship is built and maintained is, of course, critical. But he also discussed two other subjects that can potentially affect containership safety: misdeclared and overweight containers, and the desire by many companies to reduce the amount of ballast water being carried in their ships.
MM&P is part of the International Longshoremen’s Association, which has been raising the alarm for some time about the breach to safety of misdeclared and overweight containers, as has the World Shipping Council, the association which represents liner companies. When the International Maritime Organization’s Subcommittee on Dangerous Goods, Solid Cargoes and Containers meets this month, it will consider proposed amendments to the Safety of Life at Sea convention that would require the shipper to verify the weight of containers and provide that number to the shipmaster or his representative prior to loading. It seems like a sensible and overdue rule.
We haven’t heard as much about ballast water, but Werse told us the phrase “minimum water” has become “a mantra in the industry right now” and that some companies have even made the amount of water their ships carry a “key performance indicator.” Clerks monitoring data from ships at central offices, however, may tell seafarers their ships are not at maximum trim and carrying too much ballast water.
Discussing a company other than MOL, for which some of his members work, he said “that person in the office doesn’t appreciate the actual weather conditions at the time. I’ve heard our American captains, who are overly cautious—and that’s good thing, I’m one of them—had their monitoring staff call and say ‘why aren’t you trimmed by the stern.’ And he’ll say ‘we are in incredibly heavy sea, and I am taking on extra ballast, I’m not going to maintain this trim because you want to maximize fuel efficiency. I’m going to reduce the effect of the weather on the vessel and the containers.’”
He said a person in an office “doesn’t appreciate…the effect of a force 10, a force 8 storm.”
Werse followed up our conversation with a note in which he said “in a dynamic state, the longitudinal strength of ships is in a fluid state of tension (hogging) and compression (sagging) with the movement of the seas. These conditions are maximized at the mid-body.
“It does not matter if the vessel is sagging or hogging, the worst condition will take place when the wave interval is close to the vessel’s length. If the waves are much shorter, or much longer than the vessel, the bending moments will be less than if the wavelength equals the ship length,” he explained. “Add this to overloading by under-reporting of container weights and maintaining minimal safety margin of ballast water needed to reduce bending moments and you can exceed the vessel design loads.”
Ballast water exchange to prevent the transfer of invasive species from port to port, he noted, presents another major operational challenge to seafarers, as MOL knows all too well, as its ship Cougar Ace rolled onto its side in 2006 while carrying out a ballast water exchange near the Aleutian Islands. (Chris Dupin)