As a deck officer, the main responsibilities are safe navigation of ship and safe cargo handling and stowage. As the rank or responsibility of the deck officer rises, the cargo handling and stowage knowledge is must for a competent deck officer for the safety of the ship’s property and personnel.
In a container ship, a stowage plan is prepared as per the container to be discharge and loaded on a particular port along with the tanks condition i.e. mass carried by the ship other than cargo. This is done to maintain the stability of the ship at all times. Chief Officer of the ship is responsible for safe and secure stowage of the cargo on ships.
Objectives when cargo is stowed in the ship –
1. To protect the ship.
2. To protect the cargo.
3. To obtain the maximum use of the available capacity of the ship.
4. To provide for rapid and systematic discharging and loading.
5. To provide for the safety of crew and shore men at all times.
Points to remember when loading cargo container on ships:
- Over stowage should be avoided and cargo planning to be done as per the latest cargo, i.e. cargo for a later port should not be placed over that of an earlier port.
- Loading conditions must be calculated for intact stability, shearing force, bending moment, torsion moment, trim and draft etc. Torsion moment, bending moment and shear force values must not exceed 100% at any time.
- The IMO visibility line should be taken care of when planning the stowage of containers on deck.
- The stowage of IMDG containers to be done as per ships Document of compliance with the special requirements for ships carrying dangerous goods
- The GM value is affected (increases/decreases) by means of stowing light containers on top of heavy containers respectively and vice-versa.
- GM is the also known as Metacentric height which is the distance between the centre of gravity of the ship and its metacentre. The GM is responsible for deciding the stability factor of the ship.
- In a low GM situation, it is preferable for light containers to be stowed on top.
- However, usually the GM values for ship are high and stowing light containers on top of heavy ones will only increase GM leading to a “stiff” ship with short rolling periods, which increases the stresses on the lashing.
- In this situation, it is preferable for the heavy containers to be loaded on top but with due regard to lashing stresses and staking weight.
Out of Gauge or OOG Containers
OOG containers are the ones for which standard lashing equipment and procedures cannot be applied.
OOG should not be stored in outboard rows in order to prevent the OOG cargo from falling overboard if lashings break.
Stowage of OOG on deck in the foremost bay is never permitted. If possible stowage of OOG on deck of the second most forward bay also to be avoided;the main thing is to check the lashing of the OOG cargo as the stevedores lash them after loading. The OOG cargo should be secured properly and it should be ensured that the OOG cargo won’t shift or break loose.
You may also like to read-Important Points for Safe Container Lashing