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Container ship Cargo Securing Devices - How to use appropriate Lashing Gear

A ship sailing in a seaway has six degrees of motion: surge, sway, heave, roll, pitch and yaw. The ship itself bends and twists as waves pass. Hatch covers move relative to the hatch openings and container stacks move as clearances in the lashing equipment are taken up. It is the lashing system alone that resists these movements and attempts to keep the containers on board.

cargo securing devices
Lashing systems are put to the test during bad weather when failure may lead to container loss. Indeed, the growing number of containers lost overboard has caused concern throughout the marine industry. Cargo claims have increased and floating containers pose a hazard to navigation. Masters need to understand the strengths and weaknesses of container securing systems. It is essential that masters be aware of what can be done to prevent container loss.

Ships need to be fit to receive containers, with their lashing equipment in good order. Lashing areas need to be safe places for ships’ crews and stevedores to work.

Below is our guideline on container securing systems, the causes of lashing failure and to offer advice as to how losses can be minimised.

A containership cargo securing devices basically consist of portable securing devices and fixed securing devices. Fixed fittings are Stacking cones, foundations, deck foundations, lashing plates, lashing eyes, lashing pots, d-rings. Fixed fittings are integrated into the hull structure or fitted on double bottom or hatch covers.

Loose fittings are Twistlocks, stackers, bridge fittings, tension/pressure elements, spanners, lashing rods and turnbuckles.
Open turnbuckles combined with multi knob rods are used to secure containers of different heights with one rod length. For rapid adjustment and safe connection the turnbuckle is equipped with a slide nut. 50t breaking load systems are used almost exclusively (26mm rod diameter).

Regular inspection and maintenance of ships cargo securing devices must be carried out. These would include routine visual examination of components being utilized, lubrication of securing devices, repair of damaged securing devices and separating out and rejecting damaged/unusable securing devices.

An appropriate number of portable securing devices shall always be kept on board. Usually the number of securing devices required on board is governed by figures provided in the vessels cargo securing manual (for max capacity loading). Alternatively if the vessel operator requires a smaller quantity of cargo securing devices to be maintained on board, then that quantity shall be maintained.

The consideration in such case is usually the amount of cargo being carried in the given trade. However in any case, cargo that cannot be secured in accordance with the requirements of the Cargo Securing Manual due to shortage of securing devices shall not be carried.

lashing gears- fixed fitting
Lashing gears- fixed fitting
lashing gears- loose fitting
Lashing gears- loose fitting
lashing gears- loose fitting-twistlock-&-midlock
Lashing gears- loose fitting-twistlock & midlock

A proper inventory and inspection report for securing devices as required by the vessels cargo securing manual shall be periodically prepared and forwarded to the vessel operator.

Securing devices not belonging to the vessel must not be used as they may not conform to the vessels Cargo Securing Manual. There is a perennial problem of right hand and left hand twist locks finding their way on board the vessel and this can undermine the integrity of the securing arrangement.

The vessel must only have One Type of Twist lock and all of the vessels Twist locks must be painted for easy identification.

Defective securing devices shall as far as possible be repaired on board and if not possible then these shall be condemned. Shortfall of cargo securing devices shall be reported through the inventory and inspection report and requisition raised to make good such shortfall.

Various lashing devices that are common onboard containerships are explained below:

semi-automatic twistlock
Fig: Semi-automatic twistlock

Twistlock – A mechanical locking device at the corner of a container. Conventional twistlocks are locked and unlocked manually with operating rods. Rotating the movable part around a vertical axis locks the device and a container to a twistlock foundation on a hatch cover or another container. Reversing the motion effects unlocking.

Semi-automatic twistlocks are locked automatically and unlocked manually by the operating rods. Fully-automatic locks are placed in the lower corners of the container at the pier. They lock automatically after the container is placed on the top, and unlock automatically when the container is lifted.

In fig right : SAT CV-20 is fully symmetrical semi-automatic twistlock developed by MacGREGOR. When containers are loaded at a fast rate, incorect insertion of twistlock will cause major danger and delays in the cargo handling process. The CV-20 twistlock can be inserted into the container corner castings either way-up – incorrect insertion is not possible.

Container Securing

On cellular container vessels, containers are put down cell guides and landed one on top of the other. No further securing is generally required. Similar cells may also exist on deck but containers stacked on top of each other without the benefit of cell guides must be secured one to the other with twist locks and/or a combination of twist locks, lashing rod, and turnbuckles.

An approved Cargo Securing Manual (CSM) will be available on board which must be followed to ensure correct lashing and securing of the container cargo. The Cargo Securing Manual must be referred to keep a good check on the height check of the stack in order to avoid any damages to the containers while pontoon securing. This is quite often missed out when the stowage plan is issued by the planner. Responsibility lies with the duty officer for supervising the pontoon securing. An inventory is to be maintained onboard of all lashing equipment and stocks replaced without delay in cases of loss or damage.

Minimum quantity of lashings

The Cargo Securing Manual issued on ship's delivery does not detail the minimum quantity of portable securing/lashing devices that should exist on board at any time. There is no industry minimum quantity of lashing stipulated nor guidance on required percentage of spares. The minimum quantity of portable securing/lashing devices is defined by the commercial needs of the ship and therefore, the minimum quantity of portable securing/lashing devices is that required to secure the actually intended stow of containers in accordance with the lashing pattern given in the approved CSM.

The list/plan of cargo securing devices in the CSM is to be updated properly to correspond to the actual arrangement/number of cargo securing devices including some reserve supplied on board*. These amounts should be corresponding at all times. Approval of the Cargo securing manual update of list/plan by class is not necessary. A sufficient quantity of reserve cargo securing gear should also be available on board the ship Where there are insufficient lashing devices available on board, the respective containers affected will not be loaded.
*according to the guideline of 1.3.5 and 2.1.1/2.2.1 of MSC.1/Circ.1353/Rev.1
Note: - Securing/lashing must always be as per the approved lashing plan. Lashing devices must be of certified type and in acceptable condition.

Related articles on container securing arrangement

Basic guideline for Containership cargo securing

Lashing strength calculation and safety guideline

Description of various container securing arrangements

Lashing gears for containership- fixed and loose fittings

Use of gearbox in Containership cargo securing

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