Stowage plan for container ships

Stowage plan for container ships or bay plan is the plan and method by which different types of container vessels are loaded with containers of specific standard sizes. The plans are used to maximize the economy of shipping and safety on board.
Purpose.
In order to maximize the economy of handling and shipping of containers on a container ship, stowage plans sometimes known as bay plans, have become essential in the shipping trade. The plans are also vital for safety on board the ship and it is recommended that personnel working on ships are familiar with them. Modern stowage plans are executed by computer programs using mathematical calculations similar to those used for solving complicated "Tetris" problems. One such system of programs is the MACS3],[Cloud CASP], [CASP.
Containers and ship sections.
The most common and noted type of containers are the 20 feet and 40 feet containers. There are also containers with an extent in height called "High Cube" containers. The fixed exterior dimension of the standard size boxes are:
Container vessels are built to contain as many containers as possible, accordingly the vessels are divided into sections:
The cargo hold and on-deck are the spaces where the cargo, stored in containers, is kept.
Stowage terms.
On container ships the position of containers are identified by a bay-row-tier coordinate system. The bays illustrate the cross sections of the ship and are numbered from bow to stern. The rows run the length of the ship and are numbered from the middle of the ship outwards, even numbers on the port side and odd numbers on the starboard side. The tiers are the layers of containers, numbered from the bottom and up.
In the example image the position coordinates of the containers are:
Preloading planning.
In order to stow the cargo on a vessel, planners have specific computer programs to aid them. Planners use ports of call and vessel schedule to adjust vessel's route in the planning program. To plan the stowing the following parameters are essential:
After that, planners get discharge lists/plans in the form of an EDI file (the COPRAR) and send information to the container terminals for all the re-stows (discharging containers and re-loading them) which may be required for completing the discharge process. Planners will also classify the loading data according to the kind of cargo in the containers as well as the size and shape of the containers and their destinations. Each container is marked with a series of numbers and codes to identify the container's operator, specifications and what kind of cargo it may hold. The parameters are:
The stowage plan shows crossections of the ship bay by bay, to indicate where all the containers should be loaded. The plans change with each port of call as container are discharged or re-stowed and new containers are taken on board.
Cargo units.
Refrigerated cargo units – Container vessels are equipped with power source for specific places to plug in the refrigerated containers known as "reefers", hence, the reefer containers places are known and are usually the first type of containers to consider in the stowage plan.
Dangerous cargo – Containers where certain segregation rules must be followed, for example dangerous cargo that should be kept away from direct sunlight, from reefer container's motors, of some kind of another dangerous cargo or segregated away from all of the above. Accordingly, planners start with reefer units then continue with dangerous cargo units when planning the vessel.
Out of gauge cargo – For most international shipping, cargo that cannot be packed within a 40' high cube container is out of gauge. It may be possible to pack such cargo in specialty containers. Open top containers are suitable for over height cargo. flat rack containers can accommodate over height, over width or over weight cargo. Container platforms can handle over height, width or length cargo, but require slings to load and unload. Also out of gauge for most ships are containers between 45' and 53' long used in some countries for domestic rail and truck transport. These loads are usually added after planning all other containers and are usually stowed on top of other containers (on deck or in hold) as the planners strive to minimize the number of "lost slots" (unused positions) as much as possible.
Dry hide containers – Normal containers packed with cargo that may result in some leakage (such as liquid from fresh leather), they are usually stowed in outer road/first tier in order to make the necessary arrangements in case of leakage.
Dry cargo containers – Usually stowed according to next port of calls depending on container size and weight of cargos, the heavy weights below and the lighter weights on top.
Logistical factors.
Port of discharge – When trying to find a suitable stowage position for containers, the planners must take into consideration the sequence of the ports of call. For example, if the port of calls are A, B and C, for the port A discharge, the planner must take into consideration not to choose a stowage position for a container for ports B or C on top of the container destined for port A.
Container size – A 20 feet container can not be loaded up on a 40 feet container, but the reverse is possible if the vessel structure allows it. Planners can also load a 40 feet container on top of two units of 20 feet container, this known as a "Russian stowage" or "mixed stowage".
Hatch cover clearance – Hatch cover clearance refers to how many "High Cube" (height over ) containers allowed to load in the hold without preventing the hatch cover from closing correctly.
Visibility – The number of High cube containers shouldn't exceed a set number of High cube containers in each row/bay on-deck. If the number of high cube units exceeded the set number it will prevent the full/clear line of sight of the ship from the bridge or other vital vantage points.
Additional factors.
Other factors included at stowing are:
Discharging.
Once a ship has arrived in port, other plans for handling, sorting and storage at the terminal go into operation.
Problems.
As stowage plans are transmitted electronically as data files between ships and terminals, they can be intercepted by modern pirates working with organized crime syndicates. These attacks are called Major Criminal Hijacks (MCH) or South China Sea Piracy and are usually "made to order" with pirates boarding the ship having good knowledge of its layout and where the most coveted cargo is stowed.