Each container on board a container ship has a stowage position. Bay plan (stowage plan) is a diagram used for stowage planning (ship loading). It shows the cross section of a ship, with the stowage positions of each container.
A unique six digit number is allocated for every such positions, eg:- 020584. This number indicates on which Bay , on which Row at what height (tier) the container is positioned, 02 (Bay)/05(Row)/84(tier) on board the ship.
A bay on a ship can be compared to a slice on a loaf of bread. Each bay is given a 2 digit number, 0dd numbers (01,03,05..) for 20’ bays and even (02,04,06..) numbers for 40’ bays. The number increases form bow to stern. The first 2 digits on the stowage position indicates the bay and it identifies the position of the container (Lengthwise), fore , mid and aft, on the ship.
The 3rd and 4th digits on the stowage position indicate the row in which the container is stowed. It identifies the position of the container left to right (width wise) on the ship. Starting from centreline of the ship , rows to the right (starboard) have odd numbers and rows to the left (port) have even numbers. For the ships which have even number of rows in total (15,17,19..), the centre row is numbered “00”.
The Tier (height)
The bay and row position indicates whether the container is towards bow or stern and whether it is positioned towards left (portside) or right (starboard side) on the ship. The tier indicates at what height the container is stowed. Containers stacked at the bottom of ships are numbered 02, which grows upwards 04,06,08.., in the under deck stack. Whereas numbering on deck starts from 82 for containers stacked on the hatch cover and the numbers grow upwards , 84,86,88…for on deck stacking.
So , stowage position 020584 indicates that the container is on a 40’ bay near the bow , 3rd row towards right (starboard) , second tier on deck.