A stowage plan for container ships allows different types and sizes of containers to be loaded efficiently. A good plan helps to maximize the economy of scale, and it also takes many safety considerations during all stages of loading, carrying, and discharging cargo. Particular attention must also be paid to the hydrodynamic design of container ships that operate at high cruising speeds. The tall, heavy deck loads cause problems with righting capacity. For adequate stability, most container ships thus have to carry liquid ballast and be broader amidships.
The capsize risk of the vessels can be kept within acceptable
limits by high values of the roll moment of inertia.
Large ballast capacities and high power pumps are essential,
both for trimming the ships and for offsetting longitudinal bending moments.
Shipbuilders can tailor characteristics by selecting appropriate ratios between length, beam, molded depth, draft, and other dimensions.
The deadweight and hold capacity of container ships may also be stated in metric tons and cubic meters. The number of available slots for 20' or 40' containers, however, is more meaningful. TEU means "Twenty-foot Equivalent Unit", while FEU means "Forty-foot Equivalent Unit".
Standard loading conditions: Loading conditions to be examined to assess whether the stability criteria are met. For a cargo ship, the standard loading
conditions are as follows-
Ship in the fully loaded departure condition with cargo homogeneously distributed
throughout all the cargo spaces and with full stores and fuel.
- Ship in the fully loaded arrival condition with cargo homogeneously distributed
throughout all the cargo spaces and with 10% stores and fuel.
- Ship in ballast in the departure condition without cargo but with full stores and
fuel.
- Ship in ballast in the arrival condition without cargo and with 10% stores and fuel
remaining.
Stress Stability :
The Master is responsible for ensuring that, at all loading conditions, the ship satisfies the permissible Stress/Stability criteria.
The Chief Officer is responsible for making the Stability/Stress/Trim calculations and for reporting the results to the Master.
Stability & Stress Calculations:
The Chief Officer must review the pre-stowage plan.
He must also review the final stowage plan presented to him by Stevedores' latest before completion of loading/discharging operations. The actual values of Stability/Stress/Stack-weights are to be compared with the permissible values during the voyage (on departure/during voyage/on arrival) and must be reported to the Master in writing (Printout). This report must also include details for Drafts (including max Air Draft), Displacement, GM, Stresses, Trim, Visibility, Cargo breakdown – including special and DG cargo summary, Ballast, Fuel tanks distribution and consumption, & Consumables, etc.
The Master must satisfy himself that the above figures are within the permissible limits. If not, and no further improvement can be achieved by means of ballasting, the Master must demand from the Stevedores to arrange cargo changes. The Master must seek clarification in case the read draught is not in line with the calculated draught due to undeclared weights.
Stability calculations to obtain the GM and bending moments must be made for all sailing and arrival conditions and for the worst possible situation to be experienced during the passage. The GM (fluid) must always be above the IMO minimum GM for that condition, and the bending moments, shearing forces, and torsional moments are within the required limits.
Copies of Stability calculations are to be signed by the Master and filed as appropriate. The Chief Officer shall calculate the ship's stability condition and print out to get a Master's signature every three days if the sailing period is longer than the three days.
Trimming Tanks Free Surface:
The free surface effect of trimming tanks and other ballast tanks in use must be taken into consideration when planning the loading/discharging operations. Wherever possible, ballast tanks must either be empty or fully pressed up.
Bridge Copy Of Stability Calculation:
A copy of the stability calculations must be posted on the bridge, and all deck and engine room officers made aware of the stability situation.
Departure Stability:
A copy of the departure stability condition for each port is to be filed on board. The Management Office may request a copy to be forwarded to the Office.
Effect Of Strong Winds:
Masters and officers must bear in mind the effects of strong winds and ice accretion on high sided vessels, especially with seven or eight tiers of containers on deck.
Flume Tanks(Passive Roll Stabilisation Tanks):
Flume stabilization tanks must be emptied or pressed up (in the case of FW) on arrival in port. If the flume tanks are to be used on the passage, the final GM must be calculated, having a due allowance for flume tank contents and free surface effect.
Stack Weight Limitation:
The Master must ensure that all Deck Officers are familiar with the Cargo Securing Manual contents, in particular the stack weight limitations for a tank top, hatch covers, and deck loading. When the final cargo distribution file is received, the Chief Officer must check and approve the stack weights on the loading computer to ensure they are within safe limits.
The Officer of the Watch must monitor compliance with the approved loading plan for which stack weights must be taken into account.
Layering Of Containers By Weight:
Whenever possible and especially with deck containers, all efforts are to be made for layering the containers with the heaviest ones on the lower tiers. It assists safe stability and reduces the strain on lashings.
Stability Computers:
The Chief Officer is responsible for running, at quarterly intervals, a test condition, and the results are to be compared with the published data approved by Class.
A printout of the results is to be maintained on board for verification purposes.
Whenever the vessel is empty the CO to make a draught survey calculation to identify the vessel light weights and compare the same with the lightship calculation from the shipyard newbuiliding
When considering the acceptability of a container cargo stowage plan, the following additional factors/guidelines concerning hull strength & stability should be taken into account:
Our additional pages contain some more useful resources
- Ship Encountering Parametric Roll In A Seaway
The term parametric roll for a container ship is used to describe the phenomenon of large unstable roll motion suddenly occurring in the head or stern seas. Due to its violent nature, the large accelerations associated with the onset of the parametric roll cause concern for container ships' safety. Possible consequences include loss of containers, machinery failure, structural damage, and even capsize....
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Action by vessels navigating in congested water
Ships navigation is referred to the voyage practices, focusing on the process of monitoring and controlling the movement of the ship from point "A" to point "B". Choosing the most optimum route while transiting through traffic-congested water is even more challenging. Specifically, due to the presence of many vessels in the vicinity, a repeated risk of collision exists....
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Action by vessels navigating in an area of restricted visibility
Ship navigation under restricted visibility circumstances is one of the most challenging tasks while accomplishing a safe voyage. The visibility is mentioned as restricted in cases that have been observed fog, heavy rain, or dust storm, all hazardous conditions to navigate. Ship navigation in such conditions doubles the likelihood of a collision or grounding. It calls for the use of specialized equipment and requires some actions to be taken by the time the ship's officer gets information of relevant weather conditions......
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How to confirm stabilty condition?
In the northern hemisphere during hurricane season, extreme weather is a common phenomenon. A big storm can run havoc even on the largest containership by tearing off its deck lashings. Most modern ships are designed to survive in harsh conditions and stay on schedule. Nevertheless, facing storms at sea is routinely an unavoidable part of life at sea. Each year substantial weather damages incur huge financial liabilities on ship operators.
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How to maintain watertight integrity?
To maintain Water tightness, Seaworthiness, Fire integrity and Security of the vessel, it is important ships personnel ensure all openings to hull below water line and above waterline ( weathertight & watertight doors etc.) are adequately secured.
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Guide to watch officer for ships navigation ?
Bridge watchkeeping is the most critical activity conducted at sea. Upon the watchkeeper's diligence rests the safety and security of the ship, her entire crew, the cargo, and the environment. It is a demanding activity, requires support, encouragement, motivation, self-discipline and a high standard of professionalism. Ships master must ensure that all watchkeepers understand the use of safety related equipment, prior to them keeping a watch......
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Heavy weather countermeasures for prudent navigator
Encountering extreme weather conditions at sea along major trade routes is a common phenomenon. Depending upon geographical location and seasonality of revolving tropical storms, a ship, therefore, need to prepare well to survive in harsh conditions. Both heavy weather and tropical storms demand of crew's preparation and immediate response.
- How to navigate vessel safely in heavy seas ?
Encountering extreme weather conditions at sea along major trade routes is a common phenomenon. Depending upon geographical location and seasonality of revolving tropical storms, a ship, therefore, need to prepare well to survive in harsh conditions. Both heavy weather and tropical storms demand of crew's preparation and immediate response.
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Meeting rough sea conditions by containerships
In heavy weather conditions where it is unsafe for ship crew to venture out on the deck for purposes of checking deck cargo securing, Master shall consider his ship handling options and heave to if required. The aim should be ensuring the safety of the vessel and its cargo.
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Checklist for calculating stability and hull strength for cargo ship
In heavy weather conditions where it is unsafe for ship crew to venture out on the deck for purposes of checking deck cargo securing, Master shall consider his ship handling options and heave to if required. The aim should be ensuring the safety of the vessel and its cargo.
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Container Ship navigation - passage planning guideline
Before proceeding to sea, the Master shall carefully check the Passage Plan, made after receiving the voyage instruction from the Charterer or the Company. Passage plan shall be made from berth to berth acting on the principle of Safety-first, while also taking operating efficiency into consideration.
The passage plan shall be prepared normally by the Second Officer, signed for approval by master and for understanding by all officers, before departure.Based on this Guide, the Master shall collect necessary information and review the Plan including Emergency Contingency Plans.
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Navigation in cold districts and countermeasures
Ocean water freezes just like freshwater, but at lower temperatures. Freshwater freezes at 32 degrees Fahrenheit, but seawater freezes at about 28.4 degrees Fahrenheit, because of the salt in it. Due to the presence of many hostile conditions, any merchant ship, while entering a freezing sea area, significant challenges are being encountered concerning safety and reliability of navigation.
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Safe anchoring - planning and operational guidance for cargo ships
For the safety of the ship, strict anchor watches must be kept when the ship is at anchor. The principal reason for keeping anchor watches by one or more sailors is to maintain the safety and security of the vessel. Anchor watches to be maintained following the Masters's orders. This should include regular inspection of lead and weight on-chain.
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Anchor watch check item - deck officers guideline
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How to deal with a damaged anchor?
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When a part of the anchor chain breaks, it may be due to wear and corrosion or to over-stressing of its weakest part. Typically a ship owner arranges for anchors and chain damage inspection in a dry-dock, full range length, and can take a note on weakest links. A common defect is loose studs that reduce chain strength significantly. In all cases, the class surveyor should be consulted, and defective/ wasted chain be renewed as per surveyors' strict guidelines. It is a ship owner's routine expenditure for anchoring arrangement.
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How to recover a lost anchor ?
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After the anchor and chain are lost, the Master should make an initial report to the management company. After that, from time-to-time, the Master should report further developments. The Master should report the circumstances that led to the loss of the anchor and chain so that the Company can determine whether the general average is affected.
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What is stranding ? Investigation of possibility of self-refloating and urgency of danger
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Stranding means when a vessel has run aground, it is accidental. In consequence, the double bottom area of the vessel will probably suffer considerable damage, especially if the ground is rocky. This is physically the same action as beaching, but with the significant difference that beaching the vessel is an intentional action and under comparatively controlled conditions, whereas stranding is accidental.
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What are the emergency procedures for loss of anchor and chain?
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After the anchor and chain are lost, the Master should make an initial report to the management company. After that, from time-to-time, the Master should report further developments. The Master should report the circumstances that led to the loss of the anchor and chain so that the Company can determine whether the general average is affected.
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Securing your vessel for sea passage - when to check and what to check
Many maritime accidents are caused by the mistakes of ship personnel for inadequate sailing preparation. To avoid recurrences of the fatality deck and engine department must be well prepared before a vessel’s departure for a voyage at sea. These arrangements may include many complexities, and this is the reason why a bunch of things should be recognized and prepared delicately to ensure a smooth voyage passage and safe navigation.
Draft, Trim and Heel
IMO Intact Stability Criterion
Corrected GoM
Severe Wind and Rolling criterion
Visibility from Bridge
Propeller immersion
Shearing forces, Bending moments and Torsional moment
Other factors affecting Hull Strength and Stability as necessary
Container handling more info pages:
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Containership advantages
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Containership cargo stowage and planning
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Procedures and guidelines for dangerous cargo handling
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How to avoid irregular stowage of containers ?
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Measures against lashing failure
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Reefer container stowage guideline
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Care of Reefer container during sea passage
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Container ships procedures for securing for sea
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Deployment and monitoring of moorings and safety of crew
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Cargo securing procedure for container ship
Confirmation and record of securing
The following checklists shall be used to confirm the securing condition:
Cargo ships preparation for sailing
Checklist for Navigation in Heavy weather
Checklist for Departure
How to maintain Water tightness, Seaworthiness, Fire integrity and Security of ship ?
Securing your vessel for sea passage - when to check and what to check
Confirming stability & hull strength prior sailing
Collecting Information and Data for Passage Planning
Various Cargo handling
2 in 1 container operation in cargo hold
How to load 45 feet containers
Container damage in ''2 in 1'' cargo Operation
Containership operation detail procedure
- 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......
- Dimensions of various containers
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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
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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......
Other info pages !
Ships Charterparties Related terms & guideline
Stevedores injury How to prevent injury onboard
Environmental issues How to prevent marine pollution
Cargo & Ballast Handling Safety Guideline
Reefer cargo handling Troubleshoot and countermeasures
DG cargo handling Procedures & Guidelines
Safety in engine room Standard procedures
Questions from user and feedback Read our knowledgebase
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