Chapter 4 Flashcards
What is deck cargo
It is a cargo exposed to the elements and is subject to sea, spray and wind, as well as the additional risk of
being washed or falling overboard.
Deck cargo main considerations
Contractual/legal requirements
Prior to carrying goods on deck, the owner/carrier should be fully
satisfied that it is safe to carry such goods on deck. If not, by carrying
goods on deck, the owner/carrier may be in breach of the contract of
carriage and its P&I cover may be prejudiced.
Deck cargo main considerations
Weather
Protection from the elements is another major concern in carriage of
cargoes on deck. As the cargo on deck would be exposed to sea water,
winds and sun, their combined effect is likely to cause damage to the
cargo.
Deck cargoes must therefore be carried in appropriate packaging units,
suppliers instructions should be strictly followed and additional
protective measures such as covering them with water and weather
proof covers (tarpaulin).
Deck cargo main considerations
Access
Through and unencumbered access on deck must be provided for the
crew to carry out their normal duties and in emergencies. Deck house
water-tight doors, ventilators on deck and other hatch and store
accesses must not be blocked by cargo or lashing.
As required by the Merchant shipping (health and safety at work)
regulations 1997.
Deck cargo main considerations
Stability
Deck cargoes can cause stability issues as they generally cause loss of GM due
to their high KG (centre of gravity relative to the ship)
Stability is adversely affected whilst loading also from own ships’ gear. Loading
from either side would cause a list towards the load and loss of GM.
The list and loss of GM is at its maximum at the instant the load is picked up as
the load is furthest transversely from the centre of the vessel and the effect of
the load is at the derrick head which needs to be taken into account when
determining ship stability for the operation. It will cause stresses on the ship’s
structural parts which need to be addressed.
Deck cargo main considerations
Handling, stowing and securing
- Containers and heavy items should be stowed in the fore and aft direction
- Cargo should be secured with suitable lashings to approved securing points
- Lashings should be evenly distributed
- Where necessary dunnage can be used to fill spaces to prevent shifting, and
provide additional friction between the cargo and deck - Portable tanks should either be full or empty so as to limit free surface
effect - Stowage should be properly supervised and regular inspections should be
made throughout the voyage - All crew should be wearing proper PPE
Deck cargo main considerations
Stability and structural strength of deck
Deck cargoes also cause potential structural strength issues as deck plates are
designed to withstand a maximum weight per square area, and must not be
overloaded.
Laying down appropriate dunnage to evenly distribute the weight on deck
before the cargo is loaded on it will ensure that no section of the deck plates is
adversely affected.
Deck cargo main considerations
Windage
Deck cargoes also result in increasing the exposed windage area which will
cause increased heeling from winds, particularly from beam winds which
would result in increased heeling couple
Heave motion
Up and down vertically
Surge motion
Bow going down
Sway motion
Port to Starboard motion
Yaw movement
a side-to side movement of the bow and stern of the ship.
Pitch movement of ship
Up and down horizontally
Roll movement
Tilt- more extreme than yaw
A ship has _ degrees of freedom of movement.
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