Merchant submarine

Deutschland unloading in New London, 1916.

A merchant submarine is a type of submarine intended for trade, and being without armaments, they are not considered warships like most other submarines. The intended use would be to avoid naval blockades or to dive under arctic ice.

Strictly speaking, only two submarines have so far been purpose-built for merchant shipping use, though standard or partly converted submarines have in many cases been used to transport smaller amounts of important cargo, especially during wartime.

Deutschland

Übersicht

Only two merchant submarines have historically been built, both in Germany during World War I. They were constructed to slip through the naval blockade of the Entente Powers, mainly enforced by the efforts of Great Britain's Royal Navy. The British blockade had led to great difficulties for German companies in acquiring those raw materials which were not found in quantity within the German sphere of influence, and thus was hindering the German war efforts substantially.

The submarines were built in 1916 by a private shipping company created for the enterprise, the Deutsche Ozean-Reederei, a subsidiary company of the North German Lloyd shipping company (now Hapag-Lloyd) and the Deutsche Bank. They were intended to travel the route from Germany to the neutral U.S., bringing back the required raw materials. As the U.S. would not profit enough from receiving German currency, the ships were to carry trade goods both ways.

Britain soon protested with the U.S. against the use of submarines as merchant ships, arguing that they could not be stopped and inspected for munitions in the same manner as other vessels. The U.S., under diplomatic pressure for supposedly showing favoritism while having declared itself neutral, rejected the argument. Even submarines, as long as they were unarmed, were to be regarded as merchant vessels and accordingly would be permitted to trade.

Deutschland

The Deutschland had a carrying capacity of 700 tons (much of it outside the pressure hull), and could travel at 15 knots on the surface and 7 knots while submerged. It had a crew of 29 men and was commanded by Paul König, a former surface merchantman captain.

On its first journey to the US, departing on the 23 June 1916, Deutschland carried 163 tons of highly sought-after chemical dyes, as well as medical drugs and mail. Passing undetected through the English Channel she arrived in Baltimore on the 8 July 1916 and soon reembarked with 348 tons of rubber, 341 tons of nickel and 93 tons of tin, arriving back in Bremerhaven on 25 August 1916. She had traveled 8,450 naval miles, though only 190 of these submerged.

The profit from the journey was 17.5 million Reichsmark, more than four times the building cost, mainly because of the high prices of the patented, highly concentrated dyes, which would have cost US$1,254 per pound in 2005 dollars. In return, the raw materials brought back covered the needs of the German war industry for several months.

A second journey in October-December of the same year was also very successful, again trading chemicals, medicines and gems for rubber, nickel, alloys and tin. However, the Deutschland was lightly damaged during a collision with a tug in New London. Following his return, captain Paul König wrote a book (or possibly had it ghost-written) about the journeys of the Deutschland. The book was heavily publicized, as it was intended to sway public opinion in both Germany and the U.S.

A third journey, planned for January 1917, was however aborted after the U.S. entered the war against Germany. The declaration of war had been partly because of U.S. anger over the actions of German submarines sinking shipping bound for Great Britain, sometimes just outside of American territorial waters. The Deutschland was taken over by the German Imperial Navy and converted into the submarine cruiser U 155. It was successful in three war cruises, sinking 43 ships. After the war it was taken to England as a war trophy in December 1918. Scrapped in 1921, the boat's history ended on a tragic note, with 5 workers dying due to an explosion ripping apart the sub during dismantling.

Bremen

A second merchant submarine, the sister ship of Deutschland, was launched on its first journey in August 1916 under Karl Schwartzkopf, but never arrived in the US. Its fate was never decisively uncovered, though she may have collided with the British armed merchant cruiser HMS Mantua south of Iceland, as was theorized after the war. There are also presumptions that she might have hit a mine off the Orkney Islands.

Other boats

Six further merchant submarines were in the process of being built by the Deutsche Ozean-Reederei when the US entered the war in early 1917. The construction of the merchant submarines was subsequently halted or changed into submarine cruisers, similar to the fate of Deutschland.

In World War II, Germany used milk cow submarines to refuel its hunter u-boats in the Atlantic. As these boats were part of Kriegsmarine (Nazi Germany's navy), did carry light armaments (anti-aircraft guns), and never engaged in trade as such, they do not qualify as merchant submarines. However, they shared the large amounts of cargo space compared to normal submarines of their day.

Soviet Union

Übersicht

The Soviet Union had plans to construct cargo submarines both during World War II and in the Cold War, neither of which eventuated. These would not strictly count as merchant submarines, as they would have been at least lightly armed and used mainly for directly war-related duties, such as supplying troops or delivering military forces to their targets. However, in the post-Cold War period, Soviet designers also proposed purely peaceful applications.

World War II

In World War II, the Soviet Union used submarines (as well as other ships) to supply the besieged Crimean port of Sevastopol. The largest could transfer up to 95 tons of cargo, loading even the torpedo tubes with supplies. Around 4,000 tons were delivered by about 80 runs of 27 submarines, though Sevastopol still eventually fell.

Based on this experience, the Soviet Navy's high command initiated a transport submarine program. A first project (Project 605) envisaged a sub that would be basically a towed barge, connected to a standard sub. This idea was discarded due to difficulties with the towing. Later, a small cargo submarine design (Project 607) with a capacity of 250 to 300 tons of solid cargo and two folding cargo cranes was proposed. No weapons beyond two deck guns were envisaged, and the design borrowed many existing parts from the earlier VI and VI-bis submarine series to simplify construction. However, by 1943 the strategic situation had changed, and the plans were not executed.

Cold War

The Soviet Union envisaged and almost realized various concepts for large cargo submarines during the 1950s and 1960s, though these would not have been counted as merchant ships, being envisaged as navy landing ships to transport troops. They would have been amongst the largest submarines of their day, had they been built.

See also: Amphibious assault submarine

Post Cold War

In the 1990s, the Malachite design bureau proposed plans for submarines capable of transporting petroleum or freight containers in or through arctic regions. It was envisaged that these ships would dive under the polar ice cap to travel directly between European and Asian ports, and possibly northern Canada, with the designers noting that:

"Given equal cargo capacity, the efficiency of an underwater container ship is considerably higher, for example, than that of an icebreaker transport ship of the Norilsk type. The underwater tanker is competitive."

The tanker and container variants would follow the same design as standard military nuclear submarines, with the tanker variant carrying almost 30,000 tons of petroleum, to be loaded and discharged from surface or underwater terminals. The container carrier was to transport 912 standard (20-foot) freight containers, loaded within 30 hours through hatches, assisted by internal conveyance systems. However, these plans came to nothing in the hard financial straits following the Soviet Union’s dissolution later in the 1990s.

A similar design has been proposed by the Rubin Design Bureau with the 'Submarine Cargo Vessel', a civilian redesign of the famous Typhoon class submarine of the Cold War.

Vereinigte Staaten

Übersicht

Similar to the post-Cold War ideas of the Soviet Union, there have been some concept plans to use atomic-powered submarine oil tankers to exploit arctic oilfields in Alaska and Siberia. General Dynamics had apparently approached German shipbuilders during the early early 1980s about the possible construction of either a US$725 million nuclear-powered or a US$700 million methane-powered version of a liquefied natural gas (LNG) submarine tanker to carry LNG from the Arctic to North America and Europe.

Other uses

Another type of 'trade usage' is the known use of recreational submarines by drug smugglers. In one case, a Colombian drug cartel was even interrupted before finishing the construction of a professional-grade, 30 m long, 200 tons carrying-capacity submarine apparently intended for the cocaine trade with the U.S. At the time of the police raid, the sub was being constructed in segmented parts in a warehouse high in the Andes near Bogotá.

See also

• Amphibious assault submarine
• Submarine Cargo Vessel