Introduction
This post will provide an insight on container lashings and equipment that is used on container ships to ensure the safe storage and carriage of cargo and in that regard there would be a lot of pictures that will help you to understand the lashing system used on board container ships and this post will be very useful for everyone especially the mariners who have never sailed on container ships.
Lashing Bars
Here we have small lashing bars as well as much longer lashing bars so you see that figure one is a lashing bar that is used for second tier container and so those are the shorter lashing bars and then figure two that you can see are much longer lashing bars. Now figure 2 might confuse you but when you look at figure two please note it’s not two separate bars there it’s actually a single bar.
It’s just trying to show you the length and how much longer it is with respect to the shorter lashing bar.The longer lashing bar is used to lash the third high container, now when we say third high that would mean if there are three containers it is used to lash the third container from the bottom, and the shorter lashing bars are used to latch the second container from the bottom.
Further in the article you’d find pictures on how it all looks and what happens with the bottom most container,because on container ships you can only rather lash three containers only and the rest of containers are pretty much dependent on the twist lock system
Now this is how a lashing bar looks like,
You can see how this is one end of the lashing bar that goes into the slot of the container and and the other end of the lashing bar is tied to a turnbuckle to the ship structure and that is how it ties together the lashing you can also see a kind of a hook protruding from underneath the container that is the hook of a twist lock It acts as a locking mechanism of a twist lock.
These are how the lashing bars are stored. Most of these lashing bars are stored near every hatch cover where the containers are loaded on deck. If they are not in use they are stored close to the hatch cover because then it is easier for the the stevadores, for them to just use it from a place which is closer to the hatch cover and then when it is not in use they are put it back into the slots.
The lashing bars you see in the picture above these are not the shorter lashing bars these are the longer lashing bars which are used to lash the third high container. If you go towards the extreme end of the picture you can see there are some turn buckles there. This is how a turnbuckle looks like,
One end goes into the lashing bar and the other end is shackled onto the ship structure, and thats how a container is connected to the ship structure and that is how the lashing mechanism works when it comes to lashing bars and turn buckles.
Twist Locks
Twist locks are used to pretty much lock all the containers and this is pretty much the only lashing that containers above the third tier are depending on.
Twist locks are placed onto the ship sockets, there are sockets available so you place the bottom most containers there, and then every tier of course the twist locks are there.They act as an additional locking mechanism, there are three types of twist lock as follows,
Conventional/Standard Intermediate Twist Lock with a handle are used to secure containers to the deck. Such Twist Locks are locked and unlocked with operating rods as shown in the illustration above.
Semi-automatic Twist Locks are used between two containers to join and secure them in place.
Semi-automatic Twistlocks are locked automatically but can be unlocked only by manual intervention by operating the operating rods.
Fully-automatic Twist Locks are placed in the lower corners of the container at the pier. They lock automatically when the container is placed on the top, and unlocks by itself when the container is lifted.
Stacking Cones
Stacking cones are normally used for under the hold cargo they are used for under the deck containers. We don’t have twist locks in under the deck because it’s hard to lock twist locks so instead stacking cones are used for under the deck cargo
Container Handling Equipment
All ISO containers have top and bottom corner fittings and they are designed to accept lifting attachments, some containers also have fork pockets for lifting by forklift truck. Now container operators actually prefer the container to remain in the trailer while it is being packed or unpacked,however there are occasions, example the unloading or loading of heavy or awkward machinery where it is suitable or more desirable to dismount the container and then load the heavy or awkward machinery and then put it back on the truck.
To do that of course we have different kind of equipment, cranes are excellent and economical means of handling the container provided that the lifting attachments are suitable.
These are power jacks,so power jacks are basically four jacks fit into the bottom corner casting of the container
They are controlled from a console so they lift and lower individually or in unison by selection.
They are either electro hydraulic or electro mechanical now manually operated versions are also available .
Overhead Traveling Cranes
They are rail mounted or they are mounted rather on an elevated track way, they straddle the container mounting or dismounting in storage areas.
They have the disadvantage of operating only over a fixed path so you cannot shift them around.
Containers have to be bought into this place here for the crane to operate and it’s not a movable crane it’s a fixed kind of a crane so you can’t take it much anywhere else
now there are variety of types but all have a horizontal boom which reaches across the width of the ship being worked and some have the ability to transport 140 feet or 2 20 feet continuous at the same time.
Mobile Gantry Cranes
They are electro hydraulic operated with self adjusting ramps to ensure even lifting of the container.
Out of balance loads are compensated by chain sling adjusters
There are two types one manually propelled and the other is propelled by diesel which can be driven and positioned by the operator
The manually propelled version when unloaded can be maneuvered and lowered as well
These equipments are very suitable for handling containers when necessary at the shippers premises, they are comparatively cheaper ,poor
Terminal container bases, depots tray stations they have very large throughputs of containers, large volume of containers have to be handled, they have to be transferred so costly equipments have to be designed to deal with such outputs.
Conclusion
These are not all the container lashing equipment used on board a container ship, but having some information about these lashing equipment will surely help a newbie boarding a container ship.