Textbook of Maritime Medicine

6.2.1   The Role of Shipping

Shipping has played an important role for hundreds of years.  Initially, the development of ships enabled new worlds to be discovered and trade to be established.  Today ships are still the most efficient vehicles for the carriage of information, people and goods around the world.  Approximately 90% of world trade is carried by sea (ISF).

A great range of specialist ship types have evolved to deal with the variety of work in ports and at sea. Some of the main categories are described below.

6.2.2   General Cargo

General Cargo Ships were once the predominant type of merchant ship.  Generally small to medium size ships, they are equipped with their own cranes or derricks for the purpose of handling their cargoes, which makes them versatile in terms of the cargo they can carry and the ports in which they are able to work.

A disadvantage of this versatility is that it can make cargo work relatively slow and may limit the possibility for the economies of scale enjoyed by many specialist vessels.

Hazards specific to this ship type tend to relate to the large number of wires, hatches and lifting gear associated with working cargo.

6.2.3   Bulk Carriers

Bulk Carriers carry unpackaged (i.e. ‘bulk’) dry cargoes, such as coal, which are poured directly into the ships’ holds.  These ships vary considerably in size from small coastal vessels to vast ships which carry tens of thousands of tonnes of cargo.

They may be equipped with their own cargo handling cranes, but often rely on shore conveyors and cranes to work cargo.

The primary hazard in these ships is loose material underfoot (e.g. piles of coal dust and particles), and large grabs operating overhead in way of hatches.

6.2.4   Ro-Ro

Ro-Ro stands for Roll on - Roll off.  It refers to ships which load and discharge cargo by means of vehicles which are driven in or out of the ship via ramps (usually at the bow or stern).

Huge Car Carriers, for example, employ this principle to transport cars between continents.  Turn round in port can be quite fast.

Moving vehicles constitute the main hazard in this type of ship.

6.2.5   Ferries

This type of ship is commonly used for transporting vehicles and passengers in short sea journeys.

Many ferries are Roll on – Roll off ships. Turn round in port can be very fast (60 - 90 minutes for some ferries).

Moving vehicles constitute the main hazard in this type of ship.

6.2.6   Cruise Ship/Liners

Easily recognised, sometimes glamorous, passenger ships and liners carry people for longer sea passages.

In the past, liners often carried migrants between continents but are now more commonly engaged in the leisure market.  Liners ply a specific route, like the Queen Mary 2 which runs across the Atlantic, whilst schedules of cruise ships vary according to ‘tours’ offered.

These ships are geared up to carry people and should not have particular hazards other than those that are unavoidable in ships, such as the gangway or storm steps.

6.2.7   Container Vessel

A ship designed to carry standard size freight containers. These ships may be small coastal ‘feeder’ vessels or vast inter-continental liners.  Container ships are usually recognised by the stacks of containers on deck.

They are usually modern, fast and efficient which mean that their stays in port are normally short (6hours to 24 hours).

Main hazards are heavy deck lashings which may be lying about the deck or fall from above and containers being lifted overhead.  Many containers do contain dangerous goods which can, occasionally, leak.

6.2.8   Oil Tankers

Oil Tankers carry oil, or oil products, in bulk.

The cargoes are pumped directly into or out of the ship’s tanks.  Tankers have their own cargo handling pumps which are housed in a Pump Room low down in the ship.  Tankers vary in size from small coastal vessels to vast ships where the crew sometimes use bicycles to get around the main deck!

The main hazard on a tanker is fire.  Precautions must be taken to prevent smoking and avoid static or sparks.  Equipment and clothing used on a tanker must be intrinsically safe (no mobile phones or ‘normal’ torches, for example) and anti-static (no ‘normal’ nylon jackets, steel tools, etc).  These ships are often bonded to the quay by means of a heavy cable to prevent build up of static electricity.  In the event of an electrical storm cargo work may be suspended.

6.2.9   Gas Tankers

Gas Tankers carry liquefied gas in bulk and vary in size from small coastal ships to huge vessels.  They fall into two main categories and are designed to carry either liquefied petroleum gas (LPG, such as butane or propane) or liquefied natural gas (LNG – methane).

In both cases the gas is pumped directly into and out of the ship’s tanks.  The gas is kept in liquid state by refrigeration or pressurisation, or a combination of these, depending on the design of the ship.  There may be plant onboard to perform these functions.

The main hazard in these ships is the same as those for Oil Tankers, i.e. fire.  Another hazard in gas tankers is that the cargo may be carried at very low temperatures (-163ْ C in LNG ships).This means that cargo pipelines and any spillages may ‘burn’ items in contact with them.

6.2.10  Chemical Tankers

Chemical tankers tend to be smaller, complex vessels with many cargo tanks (about 30).  They are capable of carrying many different categories of chemicals in bulk and have individual tanks and cargo pipelines constructed from different material to cope with different cargoes.

The hazards in chemical tankers are similar to gas tankers, that is, fire and contact with the cargo.

 Other Tankers include those designed to carry edible oils, molasses, etc..

6.2.11   Supply & Stand By Vessels

Supply vessels and stand by vessels work in offshore oil and gas fields.  Supply vessels carry supplies to and from offshore installations on a flat deck at the aft end of the ship and in tanks below deck.

Stand-by vessels wait in the vicinity of offshore fields to ‘guard’ the fields against traffic which may stray too close to the offshore installations and to respond in the event of an emergency in the field.

Hazards associated with this type of ship are those connected with working cargo, such as gear about the deck and goods moving overhead.

6.2.12   High Speed Craft

High speed craft are generally employed in the short sea routes to compete with conventional passenger ferry traffic.

They are usually smaller than traditional ships, may be mono or multi hull vessels and operate at speeds in excess of 40 knots in order to halve crossing times on most routes.

Hazards inherent in this type of vessel should be restricted to those that are unavoidable in ships, such as the gangway or storm steps.

6.2.13   Tugs

Tugs may be employed in port for pushing and pulling ships manoeuvring in the harbour or for towing structures and vessels at sea.  They are normally powerful, compact vessels with specialised towing equipment on the aft deck.

The primary hazard for visitors on tugs is that alleyways and stairs tend to be narrow and steep due to the space available.

6.2.14   Fishing Vessels

Usually very hard working ships which specialise in catching fish.  They are often very small compared with merchant ships and fall into two main types :– Trawlers, which tend to have large stern mounted structures designed to handle the nets dragged astern of the ship as she makes way at sea, or Drifters, which set long nets that lie in the water before stopping to drift with the tides/current.

Hazards include the mass of gear which may be lying about the slippery decks.

Fishermen may spend days at sea often with little sleep, working in worse conditions than most seafarers. The crew may be suffering from fatigue if you visit them.

6.2.15   Fleet Auxiliary

The ‘Auxiliary’ Fleet is usually part of the merchant navy and employs civilian seafarers whilst supporting the Navy in carrying supplies and stores for the warships.

The Auxiliary fleet, therefore, have a variety of ship types, from tankers to dry cargo ships which undertake specialist work such as replenishing warships at sea, or helicopter operations.

The United States’ auxiliary fleet is known as Sealift Command.

Hazards in these vessels are similar to those for other ships of the type, e.g. Tanker.

 6.2.16   Warships and Military Vessels

Warships and military vessels, such as those of the Navy, Army and Air Force, are part of the fighting forces and are predominantly manned by service personnel, rather than civilians.

Warships undertake a variety of roles including defence, security and PR/diplomatic visits around the world, representing their government’s interests.