A modern container ship is designed like a giant rack: every container has an exact "address", so the shipping line's planners, the terminal planners and the ship's officers can all speak the same language. This lesson introduces the main parts of a container ship and how to read a bay–row–tier slot address.

This course is conceptual education. It does not replace the ship's loading computer, the stability booklet, the Cargo Securing Manual, or the approval of the master and the chief officer.

Holds, cell guides and hatch covers

A cellular container ship has holds below deck. Inside the holds are cell guides: vertical angle-shaped rails that form container-sized "cells". A crane lowers each container into a cell and the rails guide it down until it rests on the stack at the bottom of the hold. Because the rails hold them in place, containers inside cells generally do not need lashing the way on-deck containers do.

The holds are closed with hatch covers, usually large steel pontoons lifted off by crane. On top of the hatch covers, more containers are stacked as on-deck cargo. On-deck containers are exposed to wind, waves and ship motion, so they must be secured with twistlocks and lashings (covered in the VGM and lashing lesson).

The practical consequence: to discharge a container from a hold, the hatch cover must be opened, and to open the hatch cover, every container on top of it must be lifted off first. This strongly affects the loading and discharge sequence.

TEU and FEU

Ship capacity is expressed in TEU (twenty-foot equivalent units), one TEU being one 20-foot container. A 40-foot container is an FEU (forty-foot equivalent unit) and counts as 2 TEU. A ship's TEU figure is its nominal slot capacity; the number that can actually be loaded is often lower because of weight, stability, draft and bridge-visibility limits.

Bay–row–tier addressing

Each container position is written as six digits, BBRRTT: two digits for the bay, two for the row and two for the tier.

Bay (lengthwise)

Bays are counted from bow to stern.

  • Odd bays (01, 03, 05, …) are 20-foot positions.
  • Even bays (02, 06, 10, …) are used for 40-foot containers that occupy two adjacent 20-foot bays. Example: a 40-foot container occupying bays 01 and 03 is written as bay 02.

Row (athwartships)

Rows are counted outwards from the ship's centreline.

  • Even rows (02, 04, 06, …) are on the port side.
  • Odd rows (01, 03, 05, …) are on the starboard side.
  • If there is an odd number of rows, the row exactly on the centreline is numbered 00.

The higher the number, the closer the row is to the ship's side.

Tier (vertical)

Tiers are counted from the bottom upwards using even numbers.

  • In the hold, tiers usually start at 02, then 04, 06 and so on.
  • On deck, tiers usually start at 82, then 84, 86 and so on (some ships start at 80).
Example address Meaning
030206 Bay 03 (20 ft), row 02 (port, near centre), tier 06 (hold, third layer)
140182 Bay 14 (40 ft), row 01 (starboard, near centre), tier 82 (first layer on deck)
100084 Bay 10 (40 ft), row 00 (centreline), tier 84 (second layer on deck)

The convention above is the most common one, but details can differ between ships. Always check the bay plan and documents of the ship concerned.

Summary

A container ship consists of cellular holds and a deck above the hatch covers. Capacity is stated in TEU, and every slot has a bay–row–tier address: odd bays for 20 ft, even bays for 40 ft, even rows to port and odd rows to starboard, hold tiers from 02 and deck tiers from 82. You can look up other terms in the glossary.