What is a reefer vessel?
A reefer ship is a special form of cargo ship. As the name suggests, it is used to transport goods that must remain refrigerated during the entire transport or where the cold chain must not be interrupted.
These are usually meat or fish, but fruit such as pineapples or bananas etc. can also be transported in a refrigerated ship.
Statistics show that between 1880 and 1960 meat was the most important chilled cargo internationally and the techniques of preservation and cooling have become more and more efficient over the years.
Since when do reefer vessels exist?
It can be assumed that even in ancient and later times, there were already some reefer vessels on the way. After all, cooling with ice was already known, so that, to put it simply, a refrigerated ship was a ship with integrated cooling.
The first vessels with a specially designed construction for this purpose date from the 1870s. Initially, meat was transported directly in ice, but later on, cold air was used and snake-shaped pipes filled with brine were used for cooling. These methods all worked on shorter distances, but were not suitable for overseas transport.
In 1874, the French reefer vessel “Frigorifique” was the first to use this method. The engineer Charles Tellier integrated three methyl ether compressor refrigeration machines and ensured that beef was transported from Argentina to Europe (namely to Rouen in France) for the first time towards the end of the decade.
At the same time, absorption refrigeration systems on the steamer “Paraguay” were also successful, in this case on the route between Buenos Aires and Le Havre, and in 1879 the British vessel “Strathleven” sailed from Sydney in Australia to London with an air refrigeration machine and 40 tons of mutton.
All these methods proved to be feasible, so that in the following years the transport of meat between South America and Europe or Australia and Europe via reefer ship flourished.
How does a reefer vessel work?
The methods by which a modern reefer vessel works have been known for more than 100 years, but have been refined and made more efficient.
They work with compressors that are usually equipped with ammonia, a refrigerant that has been banned in the meantime. From the outside, a reefer ship can hardly be identified and looks almost like a classic freighter. Only the white colour and the somewhat slimmer design can be mentioned as indicators.
The holds inside a reefer vessel consist of decks of 2.20 meters height each, which are called the cooling zone. Whether one or two decks form the zone can vary, as can the temperatures. It should be noted that a refrigerated ship is not necessarily able to transport frozen goods below 0°C, but is also capable of transporting fruit to its destination at low temperatures.
This is made possible above all by insulation against high (tropical) outside temperatures and compression refrigeration systems. Inside there are numerous measuring points, thanks to which temperatures are constantly monitored. In addition, due to its purpose, a reefer ship is often more heavily motorised and reaches higher speeds.
Since the 1970s, refrigerated containers have also been used, in which the refrigeration technology inside the container is fully automatic.ince the 1970s, refrigerated containers have also been used, in which the refrigeration technology inside the container is fully automatic. In the meantime, there were also “porthole containers” which had to be connected to the ship’s cooling system, but this technology is no longer up to date.
The reefer vessel - history and future
If one takes a look at the history of reefer vessels, it is by no means limited to the transport of meat since the 1870s.
Rather, the transport of bananas and other fruits has received at least as much attention. Before the introduction of refrigerated ships and the corresponding techniques, the perennials were harvested unripe, ripened on the ship and between 30 and 60 percent had to be disposed of at sea because they reached maturity too early.
At the beginning of the 20th century, banana freighters were still sailing without refrigeration and were characterized above all by speed. The first banana ships as reefer vessels were developed by the United Fruit Company in 1903. One year later, the first ships of this type were already in series production. Important for the early transport of bananas and ripening fruit was the removal of heat as well as CO2, ethylene and water from the hold to prevent post-ripening.
The future is more than uncertain for reefer vessels, as refrigeration now takes place in the containers. In other words, there is no longer any need for ships with their own refrigeration systems, as the entire technology can be accommodated decentrally without any problems.
Already at the beginning of the 21st century, half of the reefer cargo to be transported was transported in containers specially designed for this purpose – with a strong upward trend.
Integral container instead of reefer vessel
With an integral container, all the functions of a reefer vessel can be performed. All that is required is a power supply, the rest is fully automatic, and compliance with the cold chain is monitored and the data transmitted.
Specially insulated containers have been produced exclusively in China since 2007. Their share was 60 percent in 2008. Almost all container ships in service are capable of transporting refrigerated or integral containers and providing the appropriate connections. Since 2010, the proportion of slots for such containers has been around 18 percent.
All that is required is a socket for refrigerated containers and the important heat dissipation or exhaust air system. Some refrigerated containers already work with RFID chips, thanks to which the position and temperature as well as the humidity can be monitored and read around the clock. However, this technology still lacks uniform international standards for widespread use.
And the reefer ship? Statistically, there were still 985 ships sailing the world’s oceans at the beginning of 2012, but these were gradually being scrapped. Accordingly, the refrigerated ship is now only found in special shipping, and the fleet is ageing increasingly as hardly any new ships are built or put into service.
What is transported with the reefer vessel or refrigerated container?
The reefer vessel or appropriate containers are used primarily to transport meat that is in pole position. This is followed by fish and seafood, and dairy products such as cheese or butter are also not negligible and end up in the refrigerated containers time and again.
As far as fruit is concerned, bananas are the undisputed leader, followed by citrus fruits at a good distance. Depending on the season, there are also seasonal fruits such as apples or grapes, and finally there are also the “exotic” ones such as avocado, pineapple or kiwi.
Some other fruits such as melons or stone fruit as well as vegetables and finished products are also transported by refrigerated ship, but take up considerably smaller tonnages.