The Worst Naval Idea Ever: The Cruiser Submarine

There have been many great ideas for warships in naval history like battleships and aircraft carriers. But why not create a hybrid, like a Cruiser Submarine? Submarines showed very early in their existence that they could have a disproportionate impact in major wars.

They were so effective that major naval powers decided to build different types of submarines for different missions. The Japanese even tried to create dedicated submarine aircraft carriers.

These radical submarine designs had wide appeal but ultimately had limited utility, especially cruising submarines.

Designed in the interwar period, these massive submarines relied as much on big guns and turrets as on torpedoes.

Submersible warships

Cruiser submarines have their origins in two designs of the Imperial German Navy during World War I: the Type 151 class, which had seven submarines, and the Type 139 class, which had three.

Both types had torpedo tubes – two on the Type 151s, which had storage for 18 torpedoes, and six on the Type 139s, which could store 24 torpedoes – but their main armament was two huge 5-pounder deck guns, 9 inches normally installed on surface ships, which were in front and behind the conical tower.

Their massive size and displacement – around 200ft to 300ft long and over 2,000 tons submerged – enabled them to sail much farther than smaller, unassisted submarines.

Type 151 and 139 boats operated in the waters off the Azores, Africa and even the east coast of the United States, sinking dozens of ships. A Type 151 boat, U-156, became the first foreign warship to bombard the American mainland in 70 years when it fired on a Cape Cod town in July 1918.

Conceptually, the boats functioned more like navy cruisers than actual submarines – hence their name.

Cruiser submarines could patrol large areas independently for long periods of time, escort friendly ships, ambush or engage enemy ships with guns and torpedoes, lay mines, and even conduct shore bombardments.

They also exploited an interesting loophole in the Washington Naval Treaty in 1922, in which the world’s major naval powers agreed to limit the number, weight and caliber of most warships.

Submarines, however, were largely unregulated. Cruising submarines, with large torpedo magazines and big guns, were a way to augment the power of any surface fleet without violating treaty.

Several models

All major naval powers built cruiser submarines in the interwar period.

The British HMS X1 had four 5.2-inch guns in twin turrets and displaced some 3,600 tons submerged.

The Soviet Union’s 12 K-class boats were armed with two 4-inch guns and, at 320 feet long and 2,600 tons submerged, were the largest Soviet submarines until the 1950s.

Italy had two types of cruiser submarines: the Ettore Fieramosca and the four Cagni-class boats.

The Germans built some of their Type IX submarines for long range service similar to cruise submarines.

Several of the US Navy’s nine V-boats, particularly those of the Narwhal subclass, became cruiser submarines, each armed with two 6-inch guns. They saw extensive service in World War II and were perfect for insertion and supporting Marine Raiders on special operations, as well as transporting supplies to guerrillas in the Philippines.

The best-known cruise submarine in Western countries was the French Surcouf. It had two 8-inch guns in a single turret and had two swiveling external torpedo mounts with three tubes each, in addition to the standard internal torpedo load. It also carried a seaplane for reconnaissance and targeting.

Japan has embraced cruiser submarines more than any other power. Due to the large size of the Pacific, the Japanese Navy prioritized the ability to cover long distances, especially with its submarines.

The Imperial Japanese Navy had several classes of cruiser submarines, including the Type J1 and Type B1 Classes. The four J1 boats had two 5.5 inch guns. The 20 B1 boats had only one gun each but were also each equipped with a seaplane.

The submarines were very effective, particularly at the start of the war, when they sank several American ships – including the aircraft carrier USS Wasp and the cruiser USS Juneau – and bombarded the American mainland on two separate assignments.

Japanese submarines were also efficient means of transport, facilitating the transfer of critical technology between Nazi Germany and Imperial Japan.

Finally without success

Despite their long ranges and massive firepower, cruiser submarines failed to take hold.

It became apparent that they were being used to circumvent Washington’s naval treaty limits, and the restrictions on submarines were included in the following London Naval Treaty in 1930

In addition, the boats had shortcomings.

They were nowhere near as well armored as surface warships, which meant that they could not use their deck guns against warships unless the odds were strongly in their favor. Firing and using the guns also proved difficult in the confined spaces of the submarines, especially in rough waters.

Despite the early successes of the Japanese and their good use by the Americans, cruiser submarines had poor wartime records overall, especially since the navies had more advanced anti-submarine capabilities.

Almost all of the Japanese cruiser submarines were lost in action, including all but one of the B1 boats, as were three of the four Italian Cagni-class boats and almost half of the Soviet K-class boats. The Surcouf saw service in the Free French Naval Forces, but disappeared en route to the Pacific in 1942.

Ultimately, the cruiser submarine concept was abandoned in favor of smaller submarines dedicated to torpedo use, but the concept of submarines with long-range capabilities survived, leading to the development of cruise and ballistic missile submarines at the start of the cold war.

Benjamin Brimelow is a reporter for Business Insider.

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