Bay Plan

A bay plan is the graphical representation of a container vessel's stowage arrangement shown as a cross-sectional grid for each numbered bay, divided into rows (port to starboard) and tiers (bottom to top of stack). Each cell in the grid represents one 20-foot container slot, identified by a six-digit number: the first two digits denote the bay, the next two the row, and the last two the tier. The bay plan is derived from the BAPLIE electronic message and is used by ship's officers and terminal planners to visualise and verify the loading arrangement at a glance. The chief mate uses the bay plan to check that heavy containers are placed in the lower tiers, that reefer plugs are allocated to refrigerated units, that dangerous goods are in compliant positions, and that the overall weight distribution achieves acceptable stability and longitudinal bending moments. Bay plans are an essential planning tool during port calls when hundreds or thousands of containers are being loaded and discharged simultaneously. The OOW on watch uses the bay plan to identify the precise location of any container requiring attention—a reefer alarm, a damaged unit, or a dangerous goods consignment—allowing rapid and accurate directions to stevedores.