For those not familiar with the container shipping industry, the image below is representative of a plan that might be received from the vessel’s planners. This particular plan represents the after section of a hatch (bay 7) on which 20 foot containers are loaded. A modest sized feeder vessel might have up to 20 bays capable of loading 20 foot containers. If you wished to load 40 foot containers, they would take up two bays as depicted below.
The containers all have an “e” in them, indicating that they are empty. Had they been loaded, there would be a gross weight entered in metric tons. As they are empty, a standard entry of 2.5 metric tons for an empty 20 foot container is entered in the loading program. For an empty 40′ container, 4.0 metric tons would be used.
The vessel’s loading program calculates the centers of gravity of all the disparate cargo weights, the moments that result from the interaction of all these weights, the specific information about each container (dangerous cargo and/or carriage requirements) and the structure of the vessel. In the end, the program must be satisfied that certain essential areas have a safe solution – stability, strength, lashing, IMDG cargo, IMO bridge visibility and survivability being among them. If there is any question in any of these areas, the prudent mariner would make changes to the cargo stowage plan or ballast condition to ensure those areas are satisfactory.
The load pictured above satisfies all those areas, yet there is still something about it that just looks wrong. Having the highest part of a stack on the outboard side of the ship may be technically correct – in other words, the numbers work – but, it makes you wonder what seagoing experience the cargo planner has had.
You see, the cargo planner works for a particular shipping company, and is dedicated to creating the load plan. They take all the containers that need to be shipped from point “A” to point “B” and create a load plan that satisfies all the points mentioned above. The planners do this, as it would be near impossible for the vessel’s officers to do so in a timely fashion. Quite frequently, they are located in some distant country and have no contact with the vessel other than email – a distance that may raise the question, “What’s the plan behind the plan?”
Having that single container sitting outboard certainly obstructs the view in that area and having a 4-high stack outboard certainly puts a higher load on the lashing in the most vulnerable position – outboard. In this case, the vessel has cranes, so stacking those two extra containers on the centerline wouldn’t restrict any additional visibility. In addition, stacking those two extra on the centerline would distribute those extra lashing loads throughout the whole deck load, instead of just the lashings on the outboard stack.
So, Mr. Cargo Planner sitting-in-some-distant-office, what’s the plan behind the plan? Did it look neat to have those containers sitting there like buttresses on a castle? What was the rationale?