An informative video published by 3D Living Studio takes a look into how container ships are designed, loaded, and unloaded.
As explained in the video, a container ship is a specific type of cargo ship designed for the efficient transportation of standardized cargo containers. Cargo containers are commonly seen on large trucks on the road. The video provides an overview of the general design of a container ship, using a 3D model based on the MSC Crystal.
Container sizing
The sizes of container ships are typically measured in TEU (Twenty-foot Equivalent Units) and FEU (Forty-foot Equivalent Units). Fuel tanks are generally positioned near the engine room or in the double side or bottom tanks. Water ballast tanks are used to help stabilize the ship. Most container ships are equipped with hatch covers. Containers are stored both inside the hull and on top of the deck. Within the hull lies the cargo hold space, which is segmented into holds by watertight bulkheads.
One cargo hold is further divided into two sections using pillar bulkheads. Modern container ship designs often optimize the holds for 40-foot containers. Smaller ships may carry fewer than 1,000 TEU, while the largest can accommodate more than 24,000 TEU. On smaller ships, the superstructure and engine room are typically located at the aft. On larger vessels, these structures are often situated midship. On ultra-large ships, the superstructure is placed toward the front, separated from the chimney and engine room to enhance visibility from the navigation bridge and allow for additional container stacking on deck.
Twist locks keeping containers in place
Containers are connected using devices known as twist locks. This example shows a manual twist lock, featuring a lever handle that moves sideways to secure the containers together. A semi-automatic twist lock, also shown, includes a slightly tilted cone that automatically locks when pressed by the corner casting. A wire and operating rod are used for manual unlocking. Containers are stacked vertically, using the same twist lock system even when mounted on trucks.
When stowing containers, they are aligned along structures called cell guides. In the case of 20-foot containers, the risk of sliding sideways arises if corner supports are missing. To address this, 40-foot containers are often stacked on top to prevent deformation and maintain stability. Inside the hull, twist locks are not needed due to the presence of cell guides. Once the hull is fully loaded, hatch covers are closed, and additional containers are placed on deck. Since deck spaces lack cell guides, twist locks and additional lashing are required.
Lower tiers of deck containers are secured with lashings to reduce movement and structural stress. To maximize deck storage, outboard container stacks are often supported by pedestals. Refrigerated containers, or “reefers,” may also be transported.
Unloading operations and positioning protocols
After all containers are secured, the ship is ready for voyage. Despite rigorous safety protocols, mistakes may still occur, sometimes resulting in accidents. Loading and unloading containers involves the use of a container gantry crane. This crane lifts containers with a spreader equipped with twist locks, which connect to the corner castings of a container. The spreader includes image sensors for precise positioning during loading.
Loading and unloading typically takes between one to three days, depending on cargo volume. The container’s location is determined using a bay, row, and tier numbering system. Odd-numbered bays are used for 20-foot containers, while even-numbered bays accommodate 40-foot containers. Rows start from the centerline, with odd numbers on the starboard side and even numbers on the port side. Tier numbers indicate vertical position.
For example, a container labeled “300414” represents a 40-foot container in Bay 30, Row 04, Tier 14. A 20-foot container directly below would be recorded as Bay 31, Row 04, Tier 12.
