Lashing Gear for Container Vessels: "Stabilizing Needle" of Maritime Transport
The Importance of Lashing Gear for Container Vessels
The stability of a ship is the foundation for the safety of lives at sea, as well as the safety of the ship and its cargo. It is the vitality of a ship engaged in maritime transportation. Especially for container ships, the loaded containers have a significant impact on the ship's stability. If the container lashing and securing are not properly done, it brings a great safety risk to both navigation and operations, exacerbating rolling during sailing. This can easily cause cargo to shift, containers to be thrown overboard or fall, directly or indirectly threatening the safety of the ship and its crew's life and property. Therefore, lashing gear for container vessels plays an extremely important role in maritime transportation.
Types of Lashing Gear for Container Vessels
The main methods for securing containers on ships include rod systems, wire rope systems, chain systems, and twist-lock systems.
Specific lashing gear for container vessels includes lashing rods, lashing chains, turnbuckle systems, twist-locks, twist-lock connection plates, bridge fittings, stacking cones, cone plates, wrenches, and handwheels, among others.
Lashing Gear for Container Vessels: Twist Locks
These devices are used to secure containers, suitable for fixing between containers placed on the deck and hatch covers or between containers and raised foundations. There are four types of twist locks: manual (base locks), semi-automatic, fully automatic, and intelligent mid-locks.
Basic principle of manual twist locks (base locks): The end has a mushroom shape. During use, the twist lock is first inserted into the bottom holes of the four bottom corner fittings of the container, then the handle is turned to rotate the mushroom head 90° to lock the container. Base locks are only used with dovetail bases, with the same function and operation method as twist locks.
Basic principle of semi-automatic twist locks: When loading, at the dock, when the gantry crane lifts the container to a height within arm's reach, the twist lock is inserted upward into the corner fitting hole of the container. When the container is lifted onto the ship and aligned with the raised foundation or another corner fitting hole of another container, it is lowered, and the lock's automatic mechanism is activated to rotate the lock cone and connect the container to the foundation or another container, securing it in place. When unloading, the lock pin should first be pulled out with an operating rod to unlock the twist lock from the raised foundation or another container's top corner fitting hole, then the container is lifted to the dock where it can be manually removed.
Basic principle of fully automatic twist locks: One end of the twist lock is spiral-shaped. Through the weight of the container, a torque is generated as gravity acts on the spiral-shaped twist lock head, causing the head to rotate and lock the container bodies together upon release. Conversely, when the weight is removed, the twist lock will rotate back due to the spring force, thus unlocking.
Lashing Gear for Container Vessels: Bridge Fittings
These devices are used to secure containers of the same height on the topmost layer by connecting adjacent containers, forming them into an integrated whole and evenly distributing external forces received.
Basic principle of bridge fittings (bridge locks): The two lock hooks (heads) of the bridge lock are respectively inserted into the corner fitting holes of two adjacent containers. By rotating the adjustment nut, the containers are pulled tightly together.
Lashing Gear for Container Vessels: Stacking Cones
These devices are used to secure the upper and lower containers within the cargo hold. The heads of the stacking cones are fixed and have no locking function in the vertical direction, only serving the connection between containers within the hold. There are single-headed and double-headed stacking cones.
Lashing Gear for Container Vessels: Cone Plates
There are single-headed and double-headed cone plates. During use, they are placed between the base of the container position and the bottom corner fittings of the container, serving the function of positioning and preventing movement of the container.
Lashing Gear for Container Vessels: Lashing Rods
These are used for lashing containers on the deck and hatch covers. Lashing rods are used for cross-tightening operations, playing a role in resisting transverse pressure and preventing tipping. They are usually used in combination with turnbuckle systems when stacking containers, securing the container bodies and preventing sliding. Due to the low elongation rate of lashing rods, appropriate tension adjustment is necessary to prevent damage to the container or lashing device due to excessive tension.
