A ship unlike any other

The German research vessel Polarstern has been sailing through the polar regions of our planet in the service of science for more than 30 years. Many a conventional vessel would already have gone to the ship’s graveyard by this time. The Polarstern, however, defies age thanks to good care and keeps pace with the times as far as technology is concerned. In an interview Captain Uwe Pahl and Engineer Ralf Krocker talk about the capabilities of the ship and what innovations can be found on board.

The research vessel Polarstern is regarded as the flagship of the German research fleet. What distinguishes this ship from the other research vessels?

Captain Pahl: Polarstern’s special features are already expressed in its operational designation, i.e. Germany polar research and supply vessel. With a length of 118 metres Polarstern is not only the largest Germany research ship. It can also load considerable volumes of cargo for supply tasks in comparison to the other vessels. We not only use Polarstern to supply the Antarctic research station Neumayer Station III, but also stations of partner nations, such as the British Rothera station. The loaded supply goods may be general cargo lots, 20-foot containers, refrigerated lots or liquid cargo like aircraft fuel or Arctic diesel.

Ralf Krocker: Polarstern is additionally Germany’s only icegoing research vessel without any restrictions. It was built for the high ice class ARC 3 with double hull and special strengthened steel plates at bow and ice belt. The weight of this ice protection is the reason why Polarsternwith double hull and special strengthened steel plates at bow and ice belt. has an enormous draught of 11.20 metres.

Supply at the shelf ice edge

Captain Pahl: Then there is also the relatively large transport capacity. The ship can hold a total of 124 persons, of whom a maximum of 44 persons are crew members. Scientists who undertake expeditions with Polarstern experience the ship as a universal research platform. There are, for example, laboratories, 16 winches, four cranes, shipboard-based helicopters for scientific and logistics missions, complete fishery gear for bottom trawl and pelagic fishing as well as instruments for seismic research. In addition, a high-pressure compressor for 200 bar air pressure and multibeam systems are available. The latter are used to survey the deep sea and investigate the sediment layers of the seafloor. This list is by no means exhaustive, however.

Up to what ice thickness can POLARSTERN make its way through sea ice?

Captain Pahl: It’s difficult to set a limit because sea ice is always different. Winds, surface currents, tidal movements and snow cover change it constantly. As an illustrative reference figure, POLARSTERN can move through homogeneous, smooth ice having a thickness of 1.2 metres at a speed of around 4 knots (nautical miles per hour). If the ice cover is thicker or the ice floes pile up to form ice ridges that are metres thick, careful tactical navigation is the only thing that helps. Then we utilise cracks and other weak points in the ice to make our way through. If that’s not possible, the last recourse is so-called ice ramming. This means repeatedly running into the ice at full speed and with frequent run-up.

Ralf Krocker: Such a ramming operation is extremely strenuous. I’ve experienced it personally before. On that occasion we wanted to get to Neumayer Station in Antarctica. Due to the wind, however, a lot of pack ice had been pushed into Atka Bay so we had to ram. That cost us a whole week and plenty of fuel. In such situations the ship runs on all four engines, which is normally avoided as far as possible for cost reasons. The expenses for fuel is the biggest item of the operating costs.

Passage through the ice


The video shows an animation about the function of the multibeam echo sounder. With the professional echo sounder the water depth is measured by sending out electroacoustic signals to the seabed - alike the orientation of a bat works during her flight. By a net of measurements scientists are able to map the seabed and his shallows - the exciting research field of the bathymetry.

Map of the arctic seas

("Download Dataset" opens PDF with 145 MB)

Bathymetrie am AWI

Is the ship an old steamer?

Ralf Krocker: RV Polarstern grew old by means of years, but it was continuously maintained and modernized. After 15 years the vessel got the midlife conversion. The second general ouverhaul was planned to be executed after 30 years, but it was recalled when the planning for the follower ship Polarstern II was started. Now, the growing appearance of age related damage must be noticed and the repair takes place in addition to regular maintenance and modernization.

Captain Pahl: Mariners tend to endearingly personify their ship and thus one could say in this context that a person can remain enormously productive even at an advanced age through activity and a healthy lifestyle. In the figurative sense this means for our ship that continuous maintenance and modernisation of Polarstern have contributed to enabling it to perform its operational tasks without restriction and without any reduction in performance.

In 30 years technology in particular has made enormous advances. What innovations have taken place on board during this time?

Ralf Krocker: Particularly noteworthy in this connection are our further improvements in the IT sector. A computer room with computers, printers and plotters has been set up. In 2008 we installed a dedicated Internet line. Until that time the crew and scientists were only able to send their measurement data and e-mails three times a day via satellite connection. That means the e-mails were sent en bloc in the morning, at noon and in the evening. Now this can be done at any time.

Polarstern just returned from a long voyage in Antarctica. What parts of the ship have suffered from the extreme environmental conditions the most?

Captain Pahl: Sailing through ice places stress on the hull in particular. Because of the vessel’s solid design, however, no major damage has occurred thus far. The ship’s propellers are subjected to stress due to ice contact, this also applies to the helm. In the sections above water level extreme minus temperatures influence the operation of all winches and cranes. We always clear snow and any ice that forms very quickly for safety reasons – especially to ensure that we can walk on the decks without risk.

Ralf Krocker: If the ship goes into dry dock after such a long voyage, a dock inspection takes place. This means all responsible experts walk around the vessel once to see whether there are any dents in the hull – which, as a matter of fact, is always the case. The last time we discovered small holes. They never went completely through the steel plates, but were big enough in diameter that you could stick a pen through them. The rest consists of general signs of wear, such as rust, which for the most part is only superficial, however. In such cases it is sufficient to grind and repaint these areas once. Nonetheless Polarstern is operated very cautious and experienced. The nautical officers and captains deserve great praise as they very smoothly guide the ship through the ice.

What innovations are there on board the Polarstern in terms of research technology?

Captain Pahl: Currently the multibeam echo sounders of the ship are going through extensive maintenance and calibration tests. Extensive sections of the Arctic and Antarctic have not been surveyed at all yet or only to an inadequate degree. Deployment of our equipment can make a major contribution to precise coverage of the still unknown marine areas in this context. In addition, the international community is currently drawing up shipping regulations for Arctic and Antarctic marine areas that will lead to a Polar Code in the near future. The consultations will also involve a description of the specific risks for shipping in these regions that primarily include inadequate surveying. Deployment of the Polarstern with its modern surveying capabilities is certainly regarded as a key contribution in this connection.

Ralf Krocker: Another new development is WAMOS – a radar system that measures wave height, period and direction. The procedure until now has been that an experienced meteorologist observe the sea every three hours and records meteorological data as well as wave characteristics. WAMOS is designed to support these synoptic observations and perhaps even replace them in the long run. This system is still in the test phase, however.

On the speedometer

The research ice breaker Polarstern had covered 1,462,338 nautical miles in its life as a ship until 2012. Voyages in the Arctic account for 351,072 nautical miles and in the Antarctic for 681,547 nautical miles. It has sailed 429,719 nautical miles on transit routes.