What is a deck cargo?

 Lashing and securing

The phrase ‘deck cargoes’ refers to objects and/or commodities carried on the weather-deck and/or hatch-covers of a ship and thereon exposed to sun, wind, rain, snow, ice and sea, so that the packaging must be fully resistant to, or the commodities themselves not be denatured by such exposure. Even in ro-ro vessels, many areas above the actual ‘hold’ space can reasonably be considered as ‘on deck’ even though not fully exposed to the onslaught of wind and sea. The combined effects of wind, sea and swell can be disastrous. Where damage and loss occur to cargo shipped on deck at anyone’s risk and expense, the shipowners, the master and his officers, and the charterers, must be in a position to demonstrate there was no negligence or lack of due diligence on their part.

Deck cargoes, because of their very location and the means by which they are secured, will be subjected to velocity and acceleration stresses greater, in most instances, than cargo stowed below decks. When two or more wave forms add up algebraically a high wave preceded by a deep trough may occur; this may be referred to as an ‘episodic wave’: a random large wave –noticeably of greater height than its precursors or successors – which occurs when one or more wave trains fall into phase with another so that a wave, or waves, of large amplitude is/are produced giving rise to sudden steep and violent rolling and/or pitching of the ship. These are popularly – and incorrectly – referred to as ‘freak’ waves; they are not ‘freak’, however, because they can, and do, occur anywhere at any time in the open sea. The risk is extensive and predominant.

The stowage, lashing, and securing of cargoes therefore require special attention as to method and to detail if unnecessary risks are to be avoided.

Causes of losses

  • Severe adverse weather conditions.
  • Lack of appreciation of the various forces involved.
  • Ignorance of the relevant rules and guiding recommendations.
  • Cost limitation pressures to the detriment of known safety requirements.
  • Insufficient time and/or personnel to complete the necessary work before the vessel leaves port.
  • Dunnage not utilised in an effective manner.
  • Inadequate strength, balance and/or number of lashings.
  • Wire attachment eyes and loops made up wrongly, including incorrect methods of using bulldog grips.
  • Lack of strength continuity between the various securing components.
  • Taking lashing materials around unprotected sharp edges.
  • Incorrect/unbalanced stowage and inadequate weight distribution.
  • The perversity of shore-based labour when required to do the job properly.
  • Securing arrangements, both supplied and approved, not fully utilised on the voyage under consideration.

Unfortunately, despite all the loss-prevention literature available, there is a continuing incidence of the collapse and/or loss overboard of deck cargo items. Losses continue of large vehicles, rail cars, cased machinery, steel pipes, structural steelwork, packaged timber, freight containers, hazardous chemicals, boats, launches, etc. When investigated fully, the causes of such losses fall into the following random categories which are neither exhaustive as to number nor mutually exclusive in occurrence:

This last point is particularly true of ISO freight containers and timber cargoes carried on the weather-deck, and of large commercial vehicles carried in ro-ro vessels.

All interests involved in the lashing and securing of deck cargoes should bear in mind that high expense in the purchase of lashing materials is no substitute for a simple design and a few basic calculations before lashing operations commence. Other than in ro-ro and purpose-built container operations where standardization of gear and rapid loading and turnaround times pose different problems, ship masters should be encouraged – on completion of lashing operations – to make notes of the materials used, to produce a representative sketch of the lashing system, to insist upon being provided with the test/proof certificates of all lashing components involved, and to take illustrative photographs of the entire operation. These, at least, will be of great assistance to the vessel’s interest in the event of related future litigation.

General guidelines

The Merchant Shipping set out some of the general ideas to be followed when securing deck cargoes. The list of requirements is not exhaustive but provides a realistic base from which to work, and reads, inter alia:

Deck cargo shall be so distributed and stowed:

1)    as to avoid excessive loading having regard to the strength of the deck and integral supporting structure of the ship;

2)    as to ensure that the ship will retain adequate stability at all stages of the voyage having regard in particular to:

a)  the vertical distribution of the deck cargo;

b) wind moments which may normally be expected on the voyage;

c) losses of weight in the ship, including in particular those due to the consumption of fuel and stores; and

d) possible increases of weight of the ship or deck cargo, including in particular those due to the absorption of water and to icing;

3)    as not to impair the weathertight or watertight integrity of any part of the ship or its fittings or appliances, and as to ensure the proper protection of ventilators and air pipes;

4)    that its height above the deck or any other part of the ship on which it stands will not interfere with the navigation or working of the ship;

5)    that it will not interfere with or obstruct access to the ship’s steering arrangements, including emergency steering arrangements;

6)    that it will not interfere with or obstruct safe and efficient access by the crew to or between their quarters and any machinery space or other part of the ship used in the working of the ship, and will not in particular obstruct any opening giving access to those positions or impede its being readily secured weathertight.”