Japanese battleship Tosa - AbsoluteAstronomy.com

was a planned battleship

Battleship

A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

of the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

. Designed by Yuzuru Hiraga

Yuzuru Hiraga

- External links :...

, she was envisioned as the lead ship

Lead ship

The lead ship or class leader is the first of a series or class of ships all constructed according to the same general design. The term is applicable military ships and larger civilian craft.-Overview:...

of the Tosa class

Tosa class battleship

The The ships are sometimes referred to as the Kaga class, after the ship that was planned to have been completed first. battleships, known as Design A-127 during early planning, was an Imperial Japanese Navy dreadnought class planned as part of the "Eight-Eight" fleet...

of two 39900 LT (40,540 t) ships. The battleships would have been armed with ten 410 mm (16.1 in) guns and bring Japan closer to its goal of an "Eight-four" fleet (eight battleships and four battlecruiser

Battlecruiser

Battlecruisers were large capital ships built in the first half of the 20th century. They were developed in the first decade of the century as the successor to the armoured cruiser, but their evolution was more closely linked to that of the dreadnought battleship...

s). However, after the Washington Naval Conference

Washington Naval Conference

The Washington Naval Conference also called the Washington Arms Conference, was a military conference called by President Warren G. Harding and held in Washington from 12 November 1921 to 6 February 1922. Conducted outside the auspices of the League of Nations, it was attended by nine nations...

and the signing of the Washington Naval Treaty

Washington Naval Treaty

The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...

, all work on the ship was halted. With the vessel required to be destroyed in accordance with the terms of the treaty, the incomplete Tosa was then subjected to various tests to gauge the effect of Japanese weaponry before being scuttled on 9 February 1925.

Design and construction

For additional details and design information, see Tosa class battleship
Tosa class battleship
The The ships are sometimes referred to as the Kaga class, after the ship that was planned to have been completed first. battleships, known as Design A-127 during early planning, was an Imperial Japanese Navy dreadnought class planned as part of the "Eight-Eight" fleet...

Yuzuru Hiraga

- External links :...

, Tosa was intended to be part of a Japanese "Eight-four fleet", comprising eight battleships and four battlecruisers, the successor to the proposed "Eight-eight fleet

Eight-eight fleet

The was a Japanese naval strategy formulated for the development of the Imperial Japanese Navy in the first quarter of the 20th century, which laid down that the Japanese navy should include eight first-class battleships and eight armoured cruisers or battlecruisers.-History and development:The...

". Tosa and her sister ship Kaga
Japanese aircraft carrier Kaga
Kaga was an aircraft carrier of the Imperial Japanese Navy , named after the former Kaga Province in present-day Ishikawa Prefecture...

were intended to be the second set of high-speed battleships (after the Nagato class

Nagato class battleship

The were two battleships of the Imperial Japanese Navy. The name Nagato comes from the Nagato province. They were the first battleships to be built entirely in Japan...

) under the plan, and were approved for construction in the Diet's

Diet of Japan

The is Japan's bicameral legislature. It is composed of a lower house, called the House of Representatives, and an upper house, called the House of Councillors. Both houses of the Diet are directly elected under a parallel voting system. In addition to passing laws, the Diet is formally...

14 July 1917 warship-building authorization. Engineering blueprints for the two ships were completed by Japanese naval engineers in 1919. Based on Japanese studies of the British experience at the Battle of Jutland

Battle of Jutland

The Battle of Jutland was a naval battle between the British Royal Navy's Grand Fleet and the Imperial German Navy's High Seas Fleet during the First World War. The battle was fought on 31 May and 1 June 1916 in the North Sea near Jutland, Denmark. It was the largest naval battle and the only...

, the ships were to include new features over previous designs, including higher steaming speed despite increased tonnage, flush decks, and inclined armor.

Tosa was laid down

Keel

In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...

on 16 February 1920 by Mitsubishi

Mitsubishi

The Mitsubishi Group , Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese multinational conglomerate company that consists of a range of autonomous businesses which share the Mitsubishi brand, trademark and legacy...

in Nagasaki

Nagasaki

is the capital and the largest city of Nagasaki Prefecture on the island of Kyushu in Japan. Nagasaki was founded by the Portuguese in the second half of the 16th century on the site of a small fishing village, formerly part of Nishisonogi District...

. She utilized the same slipway

Slipway

A slipway, boat slip or just a slip, is a ramp on the shore by which ships or boats can be moved to and from the water. They are used for building and repairing ships and boats. They are also used for launching and retrieving small boats on trailers and flying boats on their undercarriage. The...

where, two decades later, the would be built. Tosa was originally scheduled to be launched

Ship naming and launching

The ceremonies involved in naming and launching naval ships are based in traditions thousands of years old.-Methods of launch:There are three principal methods of conveying a new ship from building site to water, only two of which are called "launching." The oldest, most familiar, and most widely...

in October 1921, but multiple strikes

Strike action

Strike action, also called labour strike, on strike, greve , or simply strike, is a work stoppage caused by the mass refusal of employees to work. A strike usually takes place in response to employee grievances. Strikes became important during the industrial revolution, when mass labour became...

delayed it until November. Ultimately, the battleship was not launched until 18 December 1921, two months behind schedule. Fitting-out

Fitting-out

Fitting-out, or "outfitting”, is the process in modern shipbuilding that follows the float-out of a vessel and precedes sea trials. It is the period when all the remaining construction of the ship is completed and readied for delivery to her owners...

commenced soon after with a projected completion date of July 1922. However, work on Tosa was halted on 5 February 1922, one day before Japan signed the Washington Naval Treaty

Washington Naval Treaty

. Under the terms of the treaty, construction of Tosa and Kaga was formally canceled on 5 May 1922.

Career

In August 1922, Tosa was moved to Kure

Kure, Hiroshima

is a city in Hiroshima prefecture, Japan.As of October 1, 2010, the city has an estimated population of 240,820 and a population density of 681 persons per km². The total area is 353.74 km².- History :...

, still incomplete. Fifty thousand people turned out to watch as the battleship was towed out of the harbor by five tugboats. The barbette

Barbette

A barbette is a protective circular armour feature around a cannon or heavy artillery gun. The name comes from the French phrase en barbette referring to the practice of firing a field gun over a parapet rather than through an opening . The former gives better angles of fire but less protection...

s for the 406 mm (16 inch) guns were in place, but no turrets

Gun turret

A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...

or weapons had been mounted, so the holes in the main deck were covered with a mesh

Mesh

Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands.-Types of mesh:...

-like material. Her hull

Hull (watercraft)

A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...

was finished, and a superstructure deck, bridge deck and conning tower

Conning tower

A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

had been fitted, along with a light signal mast

Mast (sailing)

The mast of a sailing vessel is a tall, vertical, or near vertical, spar, or arrangement of spars, which supports the sails. Large ships have several masts, with the size and configuration depending on the style of ship...

directly aft

Aft

Aft, in naval terminology, is an adjective or adverb meaning, towards the stern of the ship, when the frame of reference is within the ship. Example: "Able Seaman Smith; lay aft!". Or; "What's happening aft?"...

of the second barbette. The conning tower had to be outfitted as a bridge, as there was no other suitable location; compared with those of similar ships, it was much smaller, as it only contained two levels and bridge wing

Bridge wing

A bridge wing is a narrow walkway extending outward from both sides of a pilothouse to the full width of a ship. Officers use bridge wings when docking or maneuvering in locks and narrow waterways. Many of them are equipped with a control console allowing the rudder and engines to be controlled...

s. An exhaust pipe resembling an extremely small funnel

Chimney

A chimney is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the...

was fitted so that heat could be supplied within the ship.

Tosa remained in Kure until mid-1924. Stricken on 1 April 1924, the ship—with her hull virtually finished—was designated for use in testing the effectiveness of shells and torpedoes against its armor arrangements. As a result, in June 1924 the navy's gunnery school took possession of the hull and prepared it for testing.

Test target

During 6–13 June, Tosa was subjected to five explosions. The first involved a 100 kg (220.5 lb) Mk. I mine placed on the starboard side of the ship, 3.7 m (12.1 ft) below the waterline

Waterline

The term "waterline" generally refers to the line where the hull of a ship meets the water surface. It is also the name of a special marking, also known as the national Load Line or Plimsoll Line, to be positioned amidships, that indicates the draft of the ship and the legal limit to which a ship...

at frame 57

Frame (nautical)

In ships, frames are ribs that are bolted to the hull and run perpendicular to the keel. Frame numbers are the numerical values given to the frames; they begin at 1 with the first bow frame, and extend to the last stern frame. The total number vary per the length of a ship.- External links :*...

. The resultant explosion ruptured about 22 m² (236.8 sq ft) of hull, while dishing in another 750 sq ft (70 m²) of plating. Flooding took 23 compartments within the ship, 17 quickly and five slowly; a total of 995 long tons (1,011 t) of water entered the ship, increasing the ship's list to starboard by about 54'.

The second and fifth test charges (8 and 13 June) were both placed near the fore main battery

Main battery

Generally used only in the terms of naval warfare, the main battery is the primary weapon around which a ship was designed. "Battery" is in itself a common term in the military science of artillery. For example, the United States Navy battleship USS Washington had a main battery of nine guns...

magazines

Magazine (artillery)

Magazine is the name for an item or place within which ammunition is stored. It is taken from the Arabic word "makahazin" meaning "warehouse".-Ammunition storage areas:...

. Involving larger charges than the first—about 200 kg (440.9 lb) (a 6th year type torpedo) and 150 kg (330.7 lb) (a 9th year type mine)—they were both placed at frame 87: the second to port and 4.04 m (13.3 ft) below the waterline, the fifth to starboard and 6.34 m (20.8 ft) below. Both broached the side protection system—allowing 1,008 and 726 long tons (1,024 and 738 t) of water, respectively, to enter the ship—showing that the usual three-compartment, all-void system used in most Japanese battleships was an insufficient defense against modern torpedoes. The list incurred during test two was a 16' change, resulting in a port list of 36'; for test five these numbers were 38' and a starboard list of 48'.
Similar to two and five, tests three and four were conducted at the same frame (192) but on opposite sides. Frame 192 was in the middle of the ship, where the ship's protection system was designed to be the strongest. Test three (8 June) was a 300 kg (661.4 lb) 8th year type torpedo on the starboard side at a depth of 4.05 m (13.3 ft) under the ship's waterline; four (12 June) was a 350 kg (771.6 lb) torpedo to port, 4.9 m (16.1 ft) below the waterline. The tests ruptured 15 and 26 m² (160 and 280 sq ft), dished in 160 and 110 m² (1,700 and 1,200 sq ft) of plating, and allowed 1,203 and 1,160 long tons (1,222 and 1,180 t) of water to enter the ship. Test three allowed the most water in out of all of the tests and, as a result, the list was altered from a previous port-side 51' to a starboard-side 22'—a change of 13'. Test four went from a starboard 0' to a port 20'.

Further tests included the explosion of several Type 8 torpedoes filled with 300–346 kg (660–760 lbs) of picric acid

Picric acid

Picric acid is the chemical compound formally called 2,4,6-trinitrophenol . This yellow crystalline solid is one of the most acidic phenols. Like other highly nitrated compounds such as TNT, picric acid is an explosive...

within Tosas designed magazine for them, which was located forward of the first turret and had been considered a weak point in previous battleship designs. This caused "extreme structural damage above the waterline" to Tosa, and confirmed that any problem in that part of the ship could seriously harm it. Possible solutions included the installation of additional armor over the room or the use of walls on one side of the magazine that would be blown out and away from the ship in the event of any serious explosion inside. This would have the effect of focusing the explosion outside, minimizing structural damage to the ship itself. Another test involved the explosion of 370 kg (815.7 lb) of TNT 5 m (16.4 ft) away from the side of the ship.

Another test conducted somewhere around this time involved a 406 mm (16 in) gun firing a shell at Tosa. It fell about 25 metres (82 ft) short of the ship, but continued through the water and struck the ship near frame 228, 3.3 metres (10.8 ft) below the designed waterline

Waterline

. The result was disturbing, as the shell was able to pass through the 76 mm (3 in) armor and explode in the port engine room. As a result, 3000 long tons (3,048 t) of water was let in, and Tosas list was increased from 53' to 06'.

Results of the tests on Tosa were subsequently used in the refitting and reconstruction of existing warships. Lessons learned were also incorporated into the designs of the two superbattleships ten years later. In the latter, this meant that the side belt armor

Belt armor

Belt armor is a layer of heavy metal armor plated on to or within outer hulls of warships, typically on battleships, battlecruisers and cruisers, and on aircraft carriers converted from those types of ships....

was continued below the waterline

Waterline

and beneath the torpedo bulge so that the class would have a defense against underwater shells.

Sinking

For the next few months, Tosa was given to the Hiroshima gunnery school for use as a target. On 14 January 1925, the Navy Ministry of Japan

Ministry of the Navy of Japan

The was a cabinet-level ministry in the Empire of Japan charged with the administrative affairs of the Imperial Japanese Navy . It existed from 1872 to 1945.-History:...

ordered Tosa to be scuttled within one month's time. To ensure this, the Commander in Chief of the Kure Naval District

Kure Naval District

was the second of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included the Inland Sea of Japan and the Pacific coasts of southern Honshū from Wakayama to Yamaguchi prefectures, eastern and northern Kyūshū and Shikoku....

directed that preparations for scuttling the ship be completed by 1 February. It was planned that Tosa would be scuttled on or before 10 February after being towed by the former battleship to a location south of the Mizunokojima Lighthouse

Mizunokojima Lighthouse

is an active lighthouse located in Japan's Bungo Channel.- Specifications :The structure is located on Mizunokojima, a small rocky island roughly east-northeast from the city of Saiki, in the middle of the Bungo Channel. The light itself is above sea level, while the building is off the ground;...

and 16.1 kilometres (10 mi) west of Okinoshima Island (located southwest of the present-day Kōchi Prefecture

Kochi Prefecture

is a prefecture of Japan located on the south coast of Shikoku. The capital is the city of Kōchi.- History :Prior to the Meiji Restoration, Kōchi was known as Tosa Province and was controlled by the Chosokabe clan in the Sengoku period and the Yamauchi family during the Edo period.- Geography...

). Later that month, the United States Office of Naval Intelligence

Office of Naval Intelligence

The Office of Naval Intelligence was established in the United States Navy in 1882. ONI was established to "seek out and report" on the advancements in other nations' navies. Its headquarters are at the National Maritime Intelligence Center in Suitland, Maryland...

reported that "work on the dismantling of [Tosa] has been going on at the Kure Navy Yard and everything possible has been removed. The intention is to fill her hull with sand and gravel, tow her out to deep water near the entrance to Kure, open her sea cocks, and send her to the bottom."

Tosa was brought from Kure on 3 February to Saiki Bay in the Bungo Channel

Bungo Channel

The is a strait separating the Japanese islands of Kyūshū and Shikoku. It connects the Pacific Ocean and Seto Inland Sea. The narrowest part of this channel is the Hōyo Strait....

. She was then towed from the bay on the 6th with the intention of bringing the battleship to the designated sinking spot, but were thwarted by a strong storm and returned. A second attempt was made at 10:00 on the 8th. Explosive "mines" were embarked: two 360 mm (14.2 in) shells were placed inside Tosas double bottom

Double bottom

A double bottom is a ship hull design and construction method where the bottom of the ship has two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is somewhat higher in the ship, perhaps a few feet, which forms a...

, and two containers with 30 kg (66 lb) of Shimose powder

Shimose powder

Shimose powder was a type of explosive shell filling developed by the Japanese chemist Shimose Masachika . It was a form of picric acid used by France as melinite and by Britain as lyddite...

in each were put into the engine room on the port side. They would be detonated using electrical fuses, though time fuses were also fitted for use if the sea was calm. The explosives were triggered on the 8th, but they failed, so a contingent was sent aboard Tosa on the 9th; they opened six Kingston valve

Kingston valve

A Kingston valve is a type of valve fitted in the bottom of a ship's fuel, water and ballast tanks. Named after its inventor John Kingston , an English engineer....

s in the engine room at about 01:25. Soon after, Tosa slowly began to sink by the stern and to starboard. By 03:50, the rate increased, and the ship slipped beneath the waves by 07:00. Tosa was the tenth and final Japanese capital ship sunk or scrapped

Ship breaking

Ship breaking or ship demolition is a type of ship disposal involving the breaking up of ships for scrap recycling. Most ships have a lifespan of a few decades before there is so much wear that refitting and repair becomes uneconomical. Ship breaking allows materials from the ship, especially...

to comply with the naval treaty's stipulations.

Design and construction

Career

Test target

Sinking

See also