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Containership operation: 2 in 1 (Two in One) Loading Operations


Vessels’ cargo securing manual and loading manual shall be consulted to obtain such information as to maximum tiers of 20’ cntrs that may be loaded under-deck before capping by a 40’ containers. Any other stipulated restrictions also must be complied with.

20 feet & 40 feet mixed loading
20 feet & 40 feet mixed loading

The abbreviation "FEU" is occasionally used for "Forty foot Equivalent Unit" and refers to a 40ft container. A 40ft container comprises 2 TEUs (Twenty foot Equivalent Unit, 20ft container). Therefore: 1 FEU = 2 TEU.

Containers are rectangular box-shaped units of cargo. It is easy to stow them in classical block stowage both on and below deck. When containers are carried on deck, the ship is required to be approved for that purpose and the containers themselves are secured with twistlocks and lashings. These usually consist of steel rods and turnbuckles.
container cell guide
container cell guide


When containers are carried below deck, the containers are slotted into cell guides on a cellular container ship, or sit on the tanktop, joined together with stacking cones, in the holds of a dry cargo ship. Containers can easily be stowed in box-shaped holds; it is more difficult to carry them in the holds of a dry cargo ship fitted with side hopper tanks, in which case, buttresses may be fitted.

When carried within a cell guide framework, no further external support is generally required. When 20-foot containers are stowed below deck in 40-foot cell guides, it may be beneficial to overstow the 20-foot containers with a 40-foot container. The Cargo Securing Manual should be consulted before loading.

Containers carried on deck may be secured by twistlocks alone, provided the stack is not more than two containers high. When containers are carried three high, twistlocks alone may be sufficient depending on the weight of the containers. Horizontal movement of a deck stow is resisted by the twistlocks or cones. Lifting of containers in extreme seas is prevented by the pull-out strength of the twistlocks. The limitation of a twistlockonly stow is often the racking strength of the containers. For stows of more than three containers high, lashing rods are fitted because they provide additional racking strength.

In the early days of containerisation, lashings were fitted vertically to resist tipping. However, it soon became clear that it is more effective to arrange the lashings diagonally, so that the container and the lashings work together to resist racking. The usual arrangement is to fit one tier of lashings, placed diagonally within the width of the container, with the tops of the lashing rods placed in the bottom corner castings of the secondtier containers. This is called ‘cross-lashing’. An alternative arrangement, with the lashing rods located outside of the width of the container, is called ‘external lashing’. This is often used for high stacks which are lashed from a two-tier lashing bridge.
(Source data : A masters guide to container securing by STANDARD P&I CLUB)



Related Information:


How to load maximum number 20 feet container on deck ?

What are the extra precaution should be taken prior loading a 45 feet container on deck ?

Container damage in ''2 in 1'' cargo Operation

Modern containership & loading of various container types

How to load containers coming in different forms/sizes



Our additional pages contain somewhat larger lists of resources where you can find useful informations


Container handling more info pages:

  1. Definition of various containers in containership
    The exterior dimensions of all containers conforming to ISO standards are 20 feet long x 8 feet wide x 8 feet 6 inches high or 9 feet 6 inches high for high cube containers. Some of the most commonly used types are:Read more......


  2. Dimensions of various containers
  3. Containers are standardized cargo units. They are manufactured in a large variety of sizes and types, each designed to meet specific cargo and transportation requirements. Their length is usually 20 or 40 feet, although longer containers are used, principally in the US trade; these containers are 45, 48 and 53 feet long.
    Read more......

  4. Containership advantages : In principle they are boxes or containers within a box. These boxes or containers have dimensions of 2.60 x 2.45 m with lengths of 6.10, 9.15 and 12.20 m. Containers are made in steel, aluminium or GRP. They are also of refrigerated design, thus advantageous for long voyages between Australia or New Zealand and the UK. Read more......


  5. Containership cargo stowage and planning : When considering acceptability of a container cargo stowage plan, the following procedures / guidelines concerning cargo stowage shall be taken into account: Stacking Weights Restrictions, Lashing strength calculation, Dangerous goods stowage and segregation, Reefer Container Stowage , Out of Gauge Container Stowage , ....Read more......


  6. DG cargo handling - IMDG code guideline :The general provisions for segregation between the various classes of dangerous goods are shown in "Segregation table" (IMDG Code Chapter 7.2.1.16). In addition to the general provisions, there may be a need to segregate a particular substance, material or article from other goods which could contribute to its hazard. Read more......


  7. How to avoid irregular stowage of containers ? Stowage plan must be checked for any irregular stowage like those mentioned here : Stacking Weights, Lashing Strength, Special Container Stowage, Over-stow of Containers, Dangerous Cargo Stowage & Segregation, 20 or 40 or 45 feet Compulsory Stowage Locations, Hatch Cover Clearance (High cube containers Under Deck ), Out of Gauge Container Stowage etc.Read more......


  8. Measures against lashing failure : Lashing strength of deck cargo shall be ascertained by using the appropriate lashing strength calculation software where provided. All resulting values for lashing strength must be within the tolerance limits prescribed by vessels classification society.Read more......


  9. Reefer container stowage guideline : Reefer containers proposed for stowage must be accompanied by a reefer manifest. This reefer manifest should contain information regarding Container No., Stow position, Commodity, Temperature and Ventilation status. Read more......


  10. Care of Reefer container during sea passage :Reefer containers require special care after they are loaded on board ship. These containers need to be supplied with power, monitored closely for proper function and repaired as required in case of malfunction. Read more......


  11. Container ships procedures for securing for sea :All movable items on deck, inside accommodation and in E/R spaces, including under-deck passages and steering flat are firmly secured. Any unsecured items, in heavy weather, risk not only being damaged themselves, but could also pose a danger to vessel safety by violent contact with sensitive equipment or fittings.Read more......


  12. Deployment and monitoring of moorings and safety of crew :The Company’s Risk Assessment procedure shall be utilized to ensure that during all anticipated mooring arrangements and equipment use, the safety of crew is ensured. Read more......


  13. Cargo securing procedure for container ship :Securing equipment will vary depending on the type of ship but is likely to include; Twistlocks Lashing bars Turnbuckles Extension hooks Stacking cones (single and double) Twist Stackers Lashing D rings Shoes/Sockets for base twistlocks ...Read more......


  14. Containership operation -Check items upon completion of repair works : As the nature of container ship operation, it’s tread to be lack of stability, due to Top Heavy Load, the Master shall always take special attention for her stability. Also the Master should remind factors to cause reducing stability more such as Alternating course with Big angle of Rudder, Towing by tugs at the scene of Berthing / Un-berthing, etc. Read more......


  15. Containership operation -Cargo ventilation requirement : Cargo holds of container ships are fitted with two basic types of ventilation systems, namely natural and mechanical. Mechanical ventilation could be of either the supply or the exhaust type. Read more......


  16. Containership operation -How to avoid wet damage ? :Water entered into vessel cargo holds may cause wet damage to the cargo inside containers especially stowed on the bottom, unless the bilge water is drained in a proper and swift manner. Read more......






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