The was a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

of tanker/transport

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

s built for the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

(IJN) during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. The IJN called this type of submarine . The type name, was shortened to . The IJN designed these submarines to support

flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

s in forward areas. By the time the first submarine was finished, this capability was no longer needed and she was converted into a tanker. That boat, , was sunk on the return leg of her second voyage in 1945; the second boat, ''I-352'', was destroyed by an American air raid before she was completed. Four additional submarines were planned, but were cancelled before they were laid down.

Design and description

The ''I-351''-class submarines were ordered under the 5th Fleet Replenishment Program of 1942Jentschura, Jung and Mickel, p. 180 to support IJN flying boats in areas where there were no shore facilities and

seaplane tender A seaplane tender is a boat or ship that supports the operation of seaplanes. Some of these vessels, known as seaplane carriers, could not only carry seaplanes but also provided all the facilities needed for their operation; these ships are rega ...

s could not operate. They were designed to support up to three flying boats with fuel, ammunition, water and even replacement aircrew. These submarines had a length of overall, a

beam Beam may refer to: Streams of particles or energy *Light beam, or beam of light, a directional projection of light energy **Laser beam *Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized grou ...

of and a draft of . They displaced on the surface and submerged. They had a diving depth of and a crew of 77 officers and enlisted men plus accommodations for 13 aircrew.Carpenter & Polmar, p. 111 The boats had two propellers, each of which was driven by a

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...

as well as a

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

. This arrangement gave the ''I-351''-class submarines a maximum speed of while surfaced and submerged. They had a range of at while on the surface and at while submerged. This gave them an endurance of 60 days. Bridge of IJN submarine I-351 in 1945

The boats were equipped with four

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s in the bow and they carried four torpedoes. For surface combat they were designed to carry one deck gun, but this was unavailable when the submarines were under construction and three Type 3 mortars were substituted. The submarines were fitted with seven 25 mm Type 96

anti-aircraft gun Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...

s, in two twin and three single mounts. The ''I-351''-class submarines were initially equipped to carry of

aviation gasoline Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, whi ...

, of fresh water, and either sixty bombs or 30 bombs and 15 aircraft torpedoes. Four of the torpedoes could be replaced by an equal number of reload torpedoes for the submarine.

Boats

Construction and service

Only ''I-351'' and ''I-352'' were actually

laid down Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one o ...

, the other four submarines were cancelled before their keels were laid. ''I-351'' was modified before completion into an oil tanker. The boat made one round trip from

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

, carrying of aviation fuel, and was sunk on the return leg of her second trip in the

South China Sea The South China Sea is a marginal sea of the Western Pacific Ocean. It is bounded in the north by the shores of South China (hence the name), in the west by the Indochinese Peninsula, in the east by the islands of Taiwan and northwestern Phil ...

Stille, pp. 36–37 at coordinates by the American submarine on 14 July 1945. ''I-352'' was 90 percent complete when she was destroyed during an air raid by

Boeing B-29 The Boeing B-29 Superfortress is an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Fly ...

heavy bombers on 22 July.

Notes

Books

* * *

Design and description

Boats

Construction and service

Notes

Books

Further reading