U 212 CD, the next Norwegian submarine, yes but what for? (1/2)
June 26, 2017, the German MOD officially informed the relevant Parliament Committees about the agreements between the MODs of Germany and Norway for the common development and production program of the submarines class U 212 CD. The Norwegian decision to go German, Baltic and shallow waters oriented, means probably a lot in terms of naval strategy and needs consideration from the NATO and EU points. Over the 25 years following the fall of the Berlin wall, policing the Norwegian coasts and fjords has been the main duty of the Norwegian subs. A strategic change seems now to be dictated by the increasing Russian search of naval leadership, particularly around Europe; Russian submarines and surface combatants master the waves on the blue water lines crossing Gibraltar from Cape North to the Middle East Mediterranean moorings, or in the Baltic Sea, from St Petersburg to the Sunds.
Out of the typical recent examples of this Russian hard line is the aircraft-carrier KUZNETSOV, being deployed in November 2016 from Cape North into the Med on patrol off the Lattaquié port of Syria. It was combined with a large scale exercise of the Russian Fleet from the Barents sea into the Norwegian sea, part of the ships bound for the Norwegian coast and the straights of Dover, the others for the Iceland gap and the North Atlantic.
Not everyone knows that by the end of the year 2016, a highly significant number of Russian warships, including aircraft- carrier, guided missiles destroyers and frigates, plus four nuclear attack submarines (SSN) were dispatched into the Norwegian Sea. After weathering Cape North, the four SSNs headed South, off the Norwegian coast, one of them (Oscar class) very likely at the limit of the Norwegian territorial waters. They were tracked by the NATO Naval Forces but it could have been done more efficiently if some Norwegian submarine had been at sea, in a position to cooperate with the UK and French SSNs and track the Russian subs.
Open bar for intruders?
In October 2016, three Russian submarines intruders were reported inside a Norwegian fjord or within the Norwegian territorial waters, while a fourth one proceeded to a missile firing test nearby the Cape North. Four in a month! How many others were discrete and not reported? How many a year? It looks like Russian submarines being at home in the Norwegian waters while posing objectively a serious threat to the Norwegian shipping and territory!
The Norwegian coast line stretches over 1400 Nautical miles (2500 km) from the North Cape down to the Skagerrak and the Baltic Sea. Therefore it cannot be denied that controlling the Russian ships movements off this coast, from or into the Barents Sea is vital for Norway. A submarine tracking of their silent nuclear powered submarines, some of them most advanced and brand new (Yasen class), require modern SSKs (1) positioned off the coast of Norway, preferably in cooperation with NATO SSNs (2) operating further west, nearby the Iceland-Faeroe and Faeroe- Shetland gaps.
Of course, in terms of the RNN submarines’ capabilities, the Norwegian Sea surveillance mission is very demanding since they must keep submerged almost permanently in sectors of the North Norwegian sea or along some fjords. This requires endurance at sea (6 to 8 weeks), keeping watch in a patrol area between two long dived snorkeling transits on the way out of the home base and on the way back.
Above all, it requires silent submarines, in transit or in patrol conditions, with the best passive sonar detection ranges as possible and a secure capacity to communicate covertly with other submarines. Moreover, regarding their deterrence and self-defence missions, they must to be fitted with powerful and accurate underwater weapons.
In those respects, It can really be questioned whether the Norwegian MOD , having restricted the Navy choice to the ocean-going French Scorpene or the Baltic oriented German U 212 would not have preferred the first. But it may obviously mean that their leading requirement was the agility to move inside the narrow fjords more than a silent hunt for deep waters intruders.
French and German designs: opposite approaches?
This is quite an occasion to investigate a little bit those significant differences, if any, between the French and the German concepts and achievements in conventional submarines.
Since 60 years, German submarines, designed by IKL and built by the Nordseewerke or the HDW yards, were specifically intended to operate almost exclusively in the Baltic waters, those for the export being of a comparable vintage. They are now designed and built by the sole HDW yard in Kiel, under the name TKMS (Thyssen Krupp Marine Systems), a subsidiary of the Thyssen Krupp group,
Baltic Sea means shallow waters, with a medium depth of 56 meters, which dictates quite specific submarines. Such a thin water layer forces the transiting submarines to skim the sandy bottoms, not to be detected, neither to risk collision with deep draft merchant ships. The need to skim at sometimes rather high speed generated a development of submarines dedicated auto-pilots systems which, so far have been unique and performing.
In those waters, the submarine safety is subject to a couple of vital risks: being detected, visually or by magnetic airborne or ship borne sensors, through the thin water layer. In addition the risk of magnetic mines laid down on the sea bed is paramount. To cope with it, the German naval architects required from the steel industry the development of a non-magnetic steel best suited to the submarines operating in those shallow waters.
Such steel however, being by nature not as resilient as the HY steels for deep diving submarines, do not fully meet the requirements of navigation in great depth; in this regard they impose real limitations. Being much less resistant to the depth pressure, the submarine hull is also more vulnerable, in combat situation, to the near underwater explosions that may cause it a vital damage. Made of more resilient high tensile steel an ocean going sub would in a similar case remain safe.
The Baltic shallow waters also dictate much “lighter” submarine concept and hull systems: rather low pressure sea water circuits and hull valves, same for drainage or regulating pumps discharge pressure, low HP air blowing into the ballast tanks for surfacing the ship etc. Just let us keep in mind that a sub hull at 500m water depth will support a 50 bar pressure, while ten times less at depth 50 m! As a result, the German designed submarines are originally fitted with much lighter and less expensive hull and propulsion ancillary equipments than the ocean-going ones.
Shallow waters also generate the need for the smallest overall height of the submarine, particularly the sail (hence smaller periscopes, ESM, radar and radio hoistable masts etc) in order to minimize the risk of collision with surface ships underwater hulls. As a result, when at periscope depth, particularly when snorkeling, the ship center of gravity is closer to the surface, hence more subject to the rough seas waves sucking effect which may surface the submarine for a while, making her dangerously detectable by searching radars, particularly airborne.
Finally the water salinity in the Baltic is quite lower and variable compared to the ocean open sea, with the result to impose the Chief Naval Architect of the submarine a much broader accessible water density than it is for ocean going submarine, with the result of a bigger volume of regulating tanks onboard.
So, obliged to design exclusively Baltic submarines by the post WW2 treaties, the German builders very smartly invented the “submarine light”, cheaper than the heavy ocean ones, well tailored to the Baltic operations, served by a few unmatched experts of Baltic navigation, heirs of the famous “Atlantic wolves” and, as such acceptable by most of the sub warfare beginners worldwide.
All this combined give the Germans a commercial lead on the submarines market in terms of agility, flexibility, easy handling, reliability and price. They also look very attractive by their main equipments supplied by well known worldwide manufacturers like Siemens, MAN/MTU, Zeiss, Atlas etc, likely to offer logistic support whenever needed.
To be continued…