Considering the fact that Germany is responsible for about half of the total number of conventional submarines constructed in Europe over the past 30 years, it is not surprising that the main improvements and developments of non-nuclear propulsion systems for submarines have also been made in Germany.
There are two submarine yards in Germany, one being Thyssen Nordseewerke (1NSW) in Emden and the other, and predominant one, being Howaldtswerke-Deutsche Werft AG (HOW) in Kiel. HDW is not only involved in naval ships and submarine building but also, and mainly, in commercial ship construction. Only one shipyard is now left of the former five HDW shipbuilding places in Hamburg and Kiel The reduced number of employees (about 5,000 down from 19,000) and the offices have been concentrated at this main yard. The massive investment required for such concentration was aimed at bringing about a dramatic increase in productivity, which it has indeed.
The HDW submarine construction moved from a single-purpose yard into the new hall. A new headquarters and office building provides short distances and has intensified internal communication remarkably. The HDW business base for the business year 89190 had a turnover of approximately 750 million Deutsch Marks (DM), which is 25% below the 5-year average but still within the annual fluctuation in shipbuilding. Commercial shipbuilding and naval shipbuilding were approximately equal in turnover, while the production hours totaled about 4.2 million hours and are attnbuted much more to commercial shipbuilding than to naval activities. This difference results from the high portion of subcontracted value in prime-contractor-type naval contracts, or, as others may address it, from the relatively smaller portion of value-added by the prime contractor’s own production.
There are at present seven European shipyards engaged in the construction of conventional submarines. (Kockums, in Malmo, Sweden; HOW and TNSW in Germany; VSEL at Barrow-in-Furness, U.K.; RDM in Rotterdam, NL; DCN in Cherbourg, France; and ltalcontieri at Monfalcone, Italy). The international submarine market environment for the various European submarine yards and design capacities is about the same. Differences, however, exist in regard to each nation’s industrial structure and degree of governmental involvement in:
– technical developments, general layout or detailed design – marketing activities,
– ownership of production
-infrastructure or even personnel,
– financial guarantees or financial aid,
– assistance in the field of training and logistics,
– and many other areas of governmental involvement or interference, etc
All European submarine builders, in whatever combination of private enterprises and governmental activities, endeavor of course to:
– increase in general their submarines’ performance, (quieter, smaller crew, etc.), thus creating more attractive boats, and
– get a bigger share of the market beyond their own navy’s requirements by selling to other countries.
Success, if the number of classes developed or of submarines built is to be used as a measuring scale, is, however, distributed unequally among the European contenders.
Two thirds of the German submarine production have been exported. The total number is comprised of boats from HDW and TNSW, who now cooperate with each other, sharing internally the work which they might be able to win in the competitive international market.
Since 1960, the German submarine shipyards have been involved in the production of 109 submarines: HDW in 71 and TNSW in 38. The distribution of submarines that HDW has contracted for over the past thirty years has been to fourteen different countries. TNSW has provided submarines to four governments. It is significant that the German government has not ordered submarines since 1969, and that the relevant industrial base has been maintained during the last 22 years in the export market.
The prime-contractor principle was applied for the first time in Germany to the class 206 submarines in 1969. This means that the shipyard as the prime-contractor became responsible not only for the detailed design and construction of the platform/hull but also for the overall performance of the weapon system. The yard had to specify and guarantee performance of the combat system, the sonar and other sensors, the navigation system, radiated noise under a spectrum of operational conditions, etc. The engineering capability for optimized integration of the payload had to be developed withia the shipyard. Since contractual delivery was conditioned to take place only after successful proof of the submarine’s performance at sea (including wet firings) submarine test crews had to be established by the yard to man each boat for its four to seven months’ period of sea acceptance trials. The yard did not like such conditions at the beginning, but it soon learned about the tremendous advantage this presented.
The ability to offer, internationally, tum-key submarine projects, which means fully tested submarines including logistics, training, support of any kind etc., obviously was attractive for a lot of countries with or without submarine experience. It was also unique in Europe when compared with the more traditional distribution of responsibilities and capabilities and planning/purchase/design/construction procedures in the other countries.
The regularity of orders for 209 class submarines in small quantities in conjunction with the extremely close loop and feedback of experience gained during the operation at sea from the captain of the yard’s trial crew to the bead of the yard’s engineering department — has proven extremely beneficial and has contributed greatly to the maturity and success of the 209 class submarine. Notably, customers were satisfied and came back with repeat orders.
The widened spectrum of the yard’s capabilities and the resulting market success allowed for the continuous development of submarine equipment and subsystems (e.g., batteries with ever higher energy density, or acoustic developments on submarine diesels) at the numerous specialized subcontractors in Germany and elsewhere in Europe, which represents an industrial base indispensable for a high quality product of this kind, and not easily challenged.
Nearly every one of these boats has also some U.S. equipment onboard:
– a broad variety of mostly Air Force communication gear;
– one has a U.S. fire control system built in Glendale;
– several have ESM systems built in the Silicon Valley;
– and they cany U.S. weapons such as the Mk37, Mk48 and Harpoon.
HDW has continuously invested in optimizing the performance of diesel submarines over the last thirty years and has enjoyed a good return on that investment. One of the critical parameters for a diesel boat (besides radiated noise) is the amount of energy/battery stored or carried onboard. The development in Germany of the relative battery weight
Battery Weight + Surface Displacement = %
from the last U-Boats of World War II to the submarine classes under construction or contracted for today has been steady and is now about 15-23% vice the earlier value of 7-10%. The amount of energy available onboard for prolonged submerged operation has been a decisive design and performance criteria during the last nine decades of submersibles and submarines. Non-nuclear boats do not have a chance (and do not intend) to compete with SSNs in this regard. They follow a different pattern in mission types and deployment principles. But it may well tum out that the question of efficient use of the available energy will dominate the game in less than two decades from now.
Since self noise is of such concern, one type of coupler which is employed to connect the gearless electric propulsion motor to the propeller shaft transmits torque to the propeller shaft through pneumatic air bags. These pneumatic air bags, with adaptable air pressure, isolate structure-born noise transfer and serve also to remove and/or influence discrete frequencies radiation. The propeller being another noise generator, HDW of course uses skew-back low-speed propellers. A new type of propeller motor will reduce the existing number of revolutions by nearly half and will also obviate the need for mechanical high-power switches, with their klacks and klicks when changing speed steps. The first of these motors has been undergoing sea trials for the past two and a half years. But quieting has it’s price:
– technically in boat’s volume and weight, and
– in costs, which are a design feature as well.
There has also been a tendency to reduce relative manning. This can be expressed as “tons of surface displacement per man of the crew.” There have been several main reasons, partially compensating each other:
– increasing the comfort and standard of living deemed necessary for the crew corresponding to the socialpolitical situation and understanding in a particular country (Sweden and Australia do a lot more for their sailors than others) and also in conjunction with increased mission durations.
– increasing the payload (with requirements going up faster than electronic cabinets managed to shrink)
– increased automation and by the reduction of onboard maintenance required during a mission and in total.
It is interesting to look at the cost of a few attack submarines planned or under construction in the western world. Since the U.S. newspapers recently gave such a nice round figure of 2 billion a copy for the SEA WOLF, this figure can be used. This is not meant to be critical of the cost of the SEA WOLF. Each country knows best what it requires for its defence needs. It is included for perspective only. HOW, and this is true for all European yards, simply does not have a single customer who can ever hope to purchase such a high-cost submarine. The niche in the 400 to 500 million DM {Ed Note: about $230 – 285 million] unit price range defines the submarine market of interesl The cost for the type 212, which is the next German Navy hybrid submarine, of about 500 million DM, is based on a 7-boat order first-of-class. The worldwide accepted costefficiency of German submarines – and the resulting market success –will allow for further investment in stealth technology, both in the mechanical and the electro-magnetic frequency spectra. The size of a submarine is considered an important part of the mechanical sector. And, of course, the German yards and their subcontractors will continue to increase the submerged endurance and minimize acoustic, magnetic, and thermal signatures at the same time.
These expressed intentions, nearly a promise, lead to the field of air-independent propulsion systems. In the past, three major constraints were existing in Germany and for its submarine designers: one was a tonnage limitation, another the no nuclear limitation, the third was money. The small tonnage was suitable for boats operating in the shallow waters, the so-called “flooded meadows”, of the Baltic; an extremely tricky acoustic environment with a constant mine threat. For the submarine design engineers it was a challenge creating features and superior performance for small, and later bigger, non-nuclear underwater torpedo transportation and totally amagnetic fighting machines, called submarines. The tonnage limitation was lifted to 1,800 tons after the first export successes of the 209s. It no longer exists. The non-nuclear and money limitations allowed us to concentrate on other options for AlP. The class 208 was planned for AlP but was never built.
Nuclear technology has been continuously developed in Germany for application to non-naval programs. HDW built, in the late 60’s, a nuclear-powered commercial surface vessel, the OTIO HAHN, named after the first man to ever crack an atom. This vessel operated for several years around the world without accident or downtime. When the first core refuelling was due the reactor was replaced by diesels for the continuation of its commercial service. The German shipbuilding and nuclear industry could not expect to gain any new experience by extending the operation of the reactor at sea.
Depending on money and technology available one may choose from the menu of AlP options the solution deemed most suitable for one’s submarines having most of their duty life in the next centucy. (By the way, AlP is not as new as many may think. From late 1944 until the end of 1945, U-boats were tested in Kiel by Professor Walter having air-independent peroxyde-turbine propulsion systems.) One can easily imagine how much analysis work, studies and submarine design work had to be invested during the last 20 years before deciding about the most likely technological configuration of the class 208. This boat remained on paper due to the third constraint: money. The different developments were discontinued and locked away at the end of the 70’s. Meanwhile in Germany and for the Federal German Navy it has been decided to go for the H2J02 fuel cell system. It is important to note that during times when governmental funding of development was not available, private investment was going in and was proving that a H2/02 fuel cell submarine system could be built and safely operated by naval crews.
The land-based test facility was established at HDW in 1984 and allowed for testing the fuel cell system together with a submarine’s most important system components, which was achieved by using a full-size (depot spare) class 205 propeller motor and a submarine battery having finished its scheduled life time. In 1988189 a submarine of the class 205 was prepared for sea trials by cutting the boat and inserting the section with the energy conversion package. The LOX tank was put under the superstructure, which led to the lengthening of the latter, and the hydrogen storage tubes into pockets alongside the hull. The refuelling of the submarine was no problem at aU, H2 and 02 being normal industrial gases as they are required for welding or other industrial purposes all over the world. During the sea trials, refuelling of Ul was done in Norway and Scotland from local suppliers. The results of the sea trials were that the fuel cell system was shown to be sailor-proof. The next German Navy submarine will be a hybrid diesel-electric fuel cell submarine, called class 212.
But it is possible also to modify and convert existing submarines into hybrid boats. Similar solutions for inserted sections are on the european drawing boards for closed cycle diesel (CCD) and sterling engine packages. The differences are in cost, in radiated noise, and to some extent in weight and volume penalty as a function of power output and energy amount brought onboard. For a modified class 209 one may expect more than triplication of the deep submerged endurance at a noise level identical {for fuel cells) or nearly identical {Sterling) or not too far above (CCD) the noise level on battery only. Much better performance can be achieved if a submarine design considers the new AlP technologies from the outset. As an example, one could imagine a 2500-ton hybrid submarine with a mission endurance of 70 days, 35 days of which the submarine could stay on station without snorting a single minute. This assumes that transit to and from the operational area is done more or less in the conventional way with intermittent snorting periods.
Clearly, the best technology in the world is worthless if it is not affordable. Consequently, investment is also going into construction techniques to continuously improve productivity and hopefully continue to produce submarines which old and new customers can afford.
HDW’s new submarine construction site is complete today and has been in operation since August ’89. The synchro-lift became operational in February ’91. This facility contributes to a great saving in manhours not only in production but also in the transport of entire submarines and hull sections. An entire submarine, or individual hull sections, can be moved on cradles which slide on a fluid film in any desired direction in and outside the hall as well as on and from the synchro-lift. The submarine construction line in a huge hall is equipped with automated welding jigs. The welds are in the rod tip-down or hands-down position. Other stations are used for automatically welding ring frames and other parts of the hull. This automated welding equipment and technique has resulted in the expected reduction in construction manhours, higher quality welds with less rework, and greatly improved circularity.
The future submarines will be battery-silent throughout, they will have a multiple of today’s submerged endurance due to AlP subsystems, they will continue to require a relatively small crew, and, we hope, they will be affordable to our own Navy and other friendly customers.
