Yamato Class Battleships

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minoru genda
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Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 9:34 pm

Yamato Class Battleships

By far the largest warships of Word War II. They were also the heaviest armed and armored of all battleships. These great ships were built in complete secrecy and it was not until very late in the war that it was found out how large and powerful they really were.

IJN Yamato. History.

Design work on what was to become the largest battleships in the world started in 1934. The designs were approved and the Yamato was ordered under the 1937 Third Reinforcement program. The keel of the Yamato was laid in the building dock of the Kure naval yard on November 4,1937 and she was launched on August 8,1940. The greatest battleship ever built was completed and turned over to the Japanese navy on December 16, 1941, in the week after the outbreak of war between Japan and the United States.

Although the predominance of the battleship had been overshadowed by aircraft carriers by the time the Yamato was commissioned, the Japanese navy still placed full confidence in the newly completed battleship. She joined the 1st Battleship Division (consisting of the Nagato and Mutsu until then) immediately after commissioning and started vigorous training. On February 12, 1942 she hoisted the Admiral's flag of Admiral Isoroku Yamamoto, Commander-In-Chief Of The Combined Fleet, as his flagship.

When Admiral Yamamoto launched a wide-ranging attack upon Midway Island in June of 1942, she also participated in the battle as flagship. As the operation ended in a complete failure, she made port in the Inland Sea with her officers and crew broken-hearted at their first serious defeat.

Even after the defeat at Midway, where the Yamato and the other battleships had no chance to fight without an umbrella of aircraft, the status of the battleship group remained unchanged. It was still the main striking force for a decisive sea battle with the enemy fleet, which the Japanese Navy eagerly wanted to have once and for all. On the other hand, a decision was made to convert the Shinano into a heavy aircraft carrier.

When war efforts were directed to the Solomon Islands sparked by a surprise landing on Guadalcanal Island by the U.S. in August, 1942, the Yamato went down to Truk Island to support a series of fierce operations to recapture Guadalcanal. On February 11,1943 the Musashi took over as Yamamoto's flagship.

After the loss of Guadalcanal and the ambush and death of Yamamoto in 1943, it was decided to bring both the Musashi and the Yamato back to the homeland to cope with the increasing troubles there. Admiral Mineichi Koga was the newly appointed Commander-In-Chief.

When she arrived home she was immediately dry-docked at Kure to do minor repairs that were badly needed. In mid-1943 the Yamato sailed again to Truk to join the Musashi in protecting the Gilbert Island and the Marshall slants, however they never got a chance to engage the enemy in a fight and remained at Truk most of the time.

Towards the end of 1943 the Yamato received her first major damage from a U.S. submarine. The Yamato was entering the Truk Atoll after returning to Truk from Japan and was hit on her starboard side near turret No.3 by a torpedo. Brackets upon which the heavy side armor was fitted were damaged with a result that about 3,000 tons of water flooded into No.3 magazine room. She was then ordered to make for the homeland, where she arrived on January 16, 1944. She was dry-docked at Kure to undertake the necessary repairs and modifications to the bracket structures of side armor to correct the defects revealed by the torpedo hit. At the same time her side triple 6.1 inch turrets were removed and three twin 5"(127mm) AA guns were added to each side. The repairs and modifications were completed by April, 1944.

The Yamato was then ordered to go to the Lingga anchorage south of Singapore and join the rest of the combined fleet there. She arrived on May.1,1944. Ten days later the fleet sailed to Tawitawi in the Sulu Archipelago, which was designated as the starting point for the forthcoming showdown with the Allied Powers in the South West Pacific codenamed Operation A-Go. She was joined by the Musashi on May 16.

The 1st Battleship Division was made a supporting group for the Japanese carriers.
When the U.S. landed on Biak Island in West New Guinea towards the end of May, the Japanese navy decided to use the two Yamato's in launching a counterattack on the enemy invasion force. But this ambitious plan failed to materialize as they were recalled on their way to the invasion fleet as the new threat of the invasion of Saipan Island became imminent.

The battle of the Philippine Islands which took place in mid-June, 1944 upset any balance between the Japanese and the U.S. as the Japanese had lost 3 more carriers and most of their land based aircraft.
The undamaged Yamato and Musashi were recalled home, arriving towards the end of June.
They then prepared for the defense of the Philippines, Formosa, Okinawa and the Japanese homeland which were all threatened by invasion because of the loss of Saipan and other islands in the Mariana's chain.
Five additional triple 0.98 inch (25mm) AA machine guns were installed on the Yamato bringing the total number of 25mm up to 29.

On July 9,1944 both the Yamato and the Musashi left the homeland and hurried south to Lingga anchorage, where they arrived on July 16,1944 and underwent extensive training for the upcoming battles. As the Japanese carrier aircraft power was now virtually non-existent, the Japanese were forced to rely solely on the big guns of the battleships.

When a lookout on Suluan Island at the entrance to Leyte Gulf flashed a report of "enemy sighted and enemy landing" the surface force at Lingga was immediately alerted and Operation SHO-1 began. They left there on October 18,1944 and arrived at Brunei two days later. After refueling they left Brunei on October 22 at 1700 hours to make a daring dash through the Philippines to launch an attack upon the enemy at Leyte Gulf.

In the early morning of October 23, north east of Palawan Island, two heavy cruisers were attacked and sunk and one was badly damaged by waiting U.S. submarines. While the force was making it's way through the Sibuyan Sea on the morning of October 24, it was attacked by a large force of U.S carrier aircraft. Though the ships put up a heavy barrage of AA fire, the Musashi was singled out for most of the attack.

By the early afternoon after the second wave of planes had left, her forepart was flooded up to the third deck and she was taking on a list to port. Her speed had to be reduced to 22 knots. She had been hit in the first two waves by at least 7 bombs, 9 torpedoes and 15 or more near misses. That she could stay at 22 knots was simply amazing. It was only after the third wave of attacking planes, in which an additional 10 bomb hits were scored and 11 torpedo hits, that the Musashi started to lose maneuverability due to her worsened bow trim.

Her bow was so deeply awash that her speed had to be reduced to 6 knots. Yet she still recovered her list by 4 degrees. Towards the evening , about four and a half hours after the third attack ended, the situation suddenly became worse. Her list to port increased and she went down at 1835 hours with the loss of 1,039 officers and men out of a crew of 2,400.
The Yamato had taken two bomb hits at 1330 hours and took on 2000 tons of water and a small list which was quickly corrected. The force temporally withdrew at 1500 hours but then reversed course at 1614 and made it's way east and broke through the San Bernardino Strait to the east of the island chain in the morning of the 25th. Not only did the force encounter the enemy but at dawn it found itself within firing range of the U.S escort carrier group, Taffy III. At 0549 hours a lookout sighted mastheads at about 28,000 yards and Admiral Kurita ordered "general chase " and speed increased to 24 knots, but all cohesion broke down from there..

The Battle Of Samar Gulf began there. The Yamato opened fire at 0558 hours with her main guns in her first engagement with an enemy fleet. At 0610 she was reported to have hit the carrier Gambier Bay . She fired a total of 104-- 18 inch shells before she had to break off to evade torpedoes, Torpedo tracks were seen bearing 100 degrees of the starboard side, she turned to port, then again to almost due north to evade them. This effectively put her out of the fight along with the commander of the fleet Kurita who was on her.

One U.S. escort carrier (the Gambier Bay), two destroyers and one destroyer escort were sunk outright by the confused Japanese attack. Three Japanese cruisers were badly damaged and the other ships suffered bomb and torpedo damage from the small carriers airwings but the Yamato was basically undamaged through it all.

Despite the desperate fighting, Admiral Kurita's fighting spirit had been dashed and he called for a retreat, missing the one golden opportunity to severely damage the invasion fleet. The Yamato and the remaining Japanese forces retreated to Brunei Bay in Borneo. Because Borneo was under almost constant air attack, the ships all left there for the homeland. The Yamato left escorted by destroyers on November 16,1944 and arrived at the Inland Sea on November 23,1944.
Upon arriving her AA armament was again strengthened by the addition of another thirty five 0.98 inch(25mm) AA guns.(23 singles and 12 triples).

When the Allied landing on Okinawa touched off desperate counter attacks by the Japanese air forces in early April, 1945, the Yamato was suddenly assigned a very unusual and grim mission code-named Ten-Go.
Since the air forces were throwing everything they had, even employing suicidal attack methods in the Okinawa theater, the surface force was to use it's strength regardless of the outcome.
The Yamato was filled to half capacity with almost all the fuel oil available to the Japanese and sortied on the afternoon of April 6, 1945. She was escorted by the light cruiser Yahagi and the destroyers Isokaze, Hamakaze, Asashimo, Kasumi, Hatsushimo, Fuyuzuki, Suzutsuki and Yukikaze.
After dropping off training cadets and sick personnel, the force left Tokuyama at 1600 hours heading for Okinawa. At 0400 hours next morning they emerged into the North Pacific southeast of Kyushu. At 0900 hours the Asashimo reported that she had developed engine trouble and dropped astern. The force composed itself into a circle with the Yamato in the center.
The Ten-Go force turned southwest at 1115 hours and 15 minutes later a U.S. floatplane was spotted. The Japanese floatplanes were then flown off back to Kyushu. Soon reports were received of up to 250 aircraft heading for the force and at 1220 hours the Yamato signaled that she had detected many aircraft 33,000 yards off her port bow, just before a rain squall blotted them out.

As the rain squall cleared the last battle began. At 1252 all the ships opened fire and even the Yamato's 18 inch guns joined in firing special "shotgun" shells at the attacking aircraft. The ships were only 175 miles from Kyushu and there was now no hope of reaching Okinawa.

The light cruiser Yahagi was the first ship pounced on as she tried to lure as many planes as possible away from the Yamato. he was hit repeatedly by torpedoes and bombs and sank very shortly. The destroyers also were battered incessantly.
The Hamakaze was sunk first then the Isokaze next. The rest were battered badly but five of them made it back to Sasebo carrying the wounded.

The Yamato was hit by bombs starting at 1240 hours and then 10 minutes later she was hit on her port side by torpedoes. She then received 8 more torpedoes on her port side and two on her starboard side which served to right the ship slightly. By 1405 she could no longer maneuver and quickly lost headway. At 1417 a final torpedo hit her in the bottom as she was listing to 20 degrees and she finally rolled over.

Her No.1 magazine then exploded at 1435 sending a huge cloud of smoke not unlike an atomic mushroom cloud thousands of feet in the air (it was said the cloud could be seen from Japan.). Her crew losses were astronomical as well over three quarters of her crew died.

She received no less then 12 torpedo hits and almost 10 bomb hits.
A Japanese diving expedition found the Yamato in the 1970's and reported that the ship was in two pieces with the bow overturned and the aft section of the ship sitting with a list to port
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Re: Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 9:40 pm

IJN Musashi. History.

The keel of the Musashi was laid on a slipway in the Nagasaki yard of Mitsubushi Heavy Industries on March 29,1938. After being succesfully launched there on ovembner 1, 1940, she was completed and delivered to the Japanese Navy by her builder's on August 5, 1942. Her delivery was delayed three months becasue of extensive changes for accomodations for the Combined Fleet Headquarters and reinforcemtn of her secondary batteries.

The launching of the Musashi was quite a feat (her launching weight of 35,757 being second only to to 37,387 tons for the British Queen Mary ocean liner) and was carried out with the utmost secrecy.

She joined the 1st Battleship Division immediately after commissioning and started vigorous training. The Musashi joined the Yamato in Truk Island on January 22,1943 and became fleet flagship on February 11,1943.
After the loss of Guadalcanal and the ambush and death of Yamamoto in 1943, it was decided to bring both the Musashi and the Yamato back to the homeland to cope with the increasing troubles there. Yamamoto's ashes were carried on the Musashi. When she arrived in Yokosuka, Japan, Emporer Hirohito visited her for the first and only time.
When she arrived home she was immediately dry-docked at Kure to do minor repairs that were badly needed. In mid-1943 the Musashi sailed again to Truk to protect the Gilbert Island and the Marshall Islands,where she was joined by the Yamato, however they never got a chance to engage the enemy in a fight and remained at Truk most of the time.

The Musashi was ordered to retreat from Truk on February 10,1944 and to head to Palau atoll. On March 29,1944 she left Palau under fear of air attacks against her. That evening she was attacked by a U.S. submarine and hit by one out of three torpedoes. She was hit on the bow, recieving very little damage although seven men were killed and 11 others were wounded. She arrived in Kure on April 3.

While undergoing repairs for the torpedo damage her AA weaponry was increased. Her amiships 6.1 inch turrets were removed and three triple 0.98 inch (25mm) machine guns were installed in their place. She also recieved an additional 21 triple 0.98 inch (25mm) guns and 26 single 0.98 inch (25mm) guns. This work was completed by April,1944.
The Musashi was then ordered to go to Tawitawi in the Sulu Archipelago, which was designated as the starting point for the forthcoming showdown with the Allied Powers in the South West Pacific. She arrived there on May 16.
The 1st Battleship Division was made a supporting group for the Japanese carriers.

When the U.S. landed on Biak Island in West New Guinea towards the end of May, the Japanese navy decided to use the two Yamato's in launching a counterattack on the enemy invasion force. But this ambitious plan failed to materialize as they were recalled on their way to the invasion fleet as the new threat of the invasion of Saipan Island became imminent.
The battle of the Phillipine Islands which took place in mid-June, 1944 upset any balance between the Japanese and the U.S. as the Japanese had lost 3 more carriers and most of their land based aircraft.

The undamaged Yamato and Musashi were recalled home, arriving towards the end of June.
They then prepared for the defense of the Philippines, Formosa, Okinawa and the Japanese homeland which were all threatened by invasion because of the loss of Saipan and other islands in the Mariana's chain.

On July 9,1944 both the Yamato and the Musashi left the homeland and hurried south to Lingga anchorage, where they arrived on July 16,1944 and underwent extensive training for the upcoming battles. As the Japanese carrier aircraft power was now virtually non-existent, the Japanese were forced to rely solely on the big guns of the battleships.
When a lookout on Suluan Island at the entrance to Leyte Gulf flashed a report of "enemy sighted and enemy landing" the surface force at Lingga was immediately alerted. They left there on October 18,1944 and arrived at Brunei two days later. After refueling they left Brunei on October 22 to make a daring dash through the Phillipines to launch an attack upon the enemy at Leyte Gulf.

In the early morning of October 23, north east of Palawan Island, two heavy cruisers were attacked and sunk and one was badly damaged by waiting U.S. submarines. While the force was making it's way through the Sibuyan Sea on the morning of October 24, it was attacked by a large force of U.S carrier aircraft. Though the ships put up a heavy barrage of AA fire, the Musashi was singled out for most of the attack.

By the early afternoon after the second wave of planes had left, her forepart was flooded up to the third deck and she was taking on a list to port. Her speed had to be reduced to 22 knots. She had been hit in the first two waves by at least 7 bombs, 9 torpedoes and 15 or more near misses. That she could stay at 22 knots was simply amazing. It was only after the third wave of attacking planes, in which an additional 10 bomb hits were scored and 11 torpedo hits, that the Musashi started to lose maneuverability due to her worsened bow trim.

Her bow was so deeply awash that her speed had to be reduced to 6 knots. Yet she still recovered her list by 4 degrees. Towards the evening , about four and a half hours after the third attack ended, the situation suddenly became worse. Her list to port increased and she went down with the loss of 1,039 officers and men out of a crew of 2,400.
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Re: Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 9:51 pm

Specifications

Yamato
Builder: Kure Navy Yard.
Laid Down: 4 November 1937.
Launched: 8 August 1940.
Commissioned: 16 December 1941.
Fate: Blew up and sank on 7 April 1945 at 1435 hours south west of Kyuscho while on a suicide run to Okinawa after being hit by 11-13 torpedoes and at least 7 bombs.


Musashi
Builder: Nagasaki Yard, Mitsubishi Co.
Laid Down: 29 March 1938.
Launched: 1 November 1940.
Commissioned: 5 August 1942.
Fate: Lost headway and sank on 24 October 1944 in the Sibuyan Sea, south of Luzon after sustaining 20 torpedo hits and 17 bombs.

Particular Preparations For Construction

When the construction of the Yamato class was planned, there was no shipyard in Japan capable of building such ships without expanding it's building facilities.
Since the Japanese Navy intended to build four Yamato class ships in succession, special preparations for their construction had to be made in selected shipyards.
Some of these arrangements consisted of expanding dock capacities, building a special transport ship capable of carrying an 18 inch gun turret and hiding such a vessel behind sisal rope curtains for security reasons.
The depth of the building dock at the Kure naval yard, in which the Yamato was built, was deepened about 3 feet so that the hull could be floated in the dock.
The capacity of the gantry crane straddling the dock was increased to 100 tons in order to lift heavy armor plates. Furthermore, about a quarter of the dock at the landward end was covered with a roof to prevent it from being seen from a prominent hill nearby.
In the Yokosuka district a large dry dock was specially built and the third ship of the Yamato class, later named Shinano and converted into a carrier was built there.
The Nagasaki Yard of Mitsubishi Heavy Industries Co. Ltd. was the only other shipyard capable of building a Yamato class battleship. even with some expansion of it's facilities.
Unlike Kure's building dock a slipway was to be used for the construction there. Needless to say, the launching of a vessel weighing 30,000 tons raised various problems technically. Not only was the slipway strengthened but workshops and piers were also expanded or strengthened. The overall area of the expansion of the workshops reached a total of almost 787,401 square feet. Floating cranes of 350 tons and 150 tons were built and installed to lift heavy armor plates and gun fittings.
At Sasebo, one of the three major naval bases in Japan, a dry dock capable of accommodating a Yamato class battleship was also built.
Some measures taken to safeguard the security of the Musashi were interesting.
The slipway on which she was built was covered by a sisal rope curtain.
The total length of rope used reached 1,683 miles and it's weight totaled 408 tons. This great consumption of sisal rope caused a temporary shortage of this item on the market, and caused complaints among fishermen.
One more thing to be mentioned was the construction of a transport vessel to carry the 18 inch guns and turrets from Kure to either Nagasaki, where the Musashi was being built, or to Yokosuka, where the Shinano was to be built.
These 18 inch guns and turrets were manufactured at the Kure naval yard and they could be transported only by this specially-built vesse
Even in accommodation the Yamato had remarkable features.
She was the first Japanese warship to be equipped with an air conditioning system.
Although this comfort was not afforded to all the living quarters, the Yamato and her sister Musashi had a favorable reputation among sailors as the most comfortable ships in the Japanese Navy.

Displacement

Design: 61,890 tons.
Standard: 63,200 tons.
Trial: 69,100 tons.
Full Load: 72,809 tons

Dimensions

Overall: 863.5' (263.2m)
Waterline: 830.0' (253m)
Beam: 127.6' (38.9m)
Draught (full load): 35.62' (10.9m)

Features Of The Hull

One of the more notable features of the Yamato's hull was that her displacement/length ratio was great, and her speed/ length ratio was small, compared with other battleships. While these ratios for the IJN Nagato was 98.14 and 1.001 respectively as compared with 101 and 0.852 for the Royal Navy's battleship Nelson, those of the new Japanese battleship were 112.2 and 0.94 respectively. Moreover her block co-efficient was 0.612, perhaps the highest figure among all the battleships in the world. This meant that she had great beam and shallow draught for such a big displacement.
Reduction of the Yamato's draught as much as possible was a prime consideration, in view of port facilities and naval bases in Japan. Nevertheless her draught when fully loaded reached 35.63 feet and some areas of the naval bases and extensive portions of the approaches to dry docks used by warships of this class had to be dredged accordingly.
How to reduce the hull resistance and increase the propulsive efficiency was the next problem which the designers strove to solve. Tests were conducted with various hull models in the experimental model basin of the Naval Technical Research Establishment in Tokyo. This basin was the largest in Japan, having a length of 805.54 feet, a width of 41 feet and a depth of 21.35 feet.
These thorough and extensive experiments led to the adoption of a gigantic bulbous bow, the size of which few other naval architects had ever planned. The result was unique; the reduction of the hull resistance by the use of this bulbous bow reached 8.2% at a speed of 27 knots.
By improving the fitting of the shaft brackets and the bilge keels, a further reduction in the hull resistance was achieved. Represented in terms of effective horsepower, the former resulted in the saving of 1,900 ehp and the latter 475 ehp. Altogether including the reduction in resistance by the use of the bulbous bow, these savings totaled 7,910 shp or 15,820 shp.
In the full power trial runs, the 69,500 ton Yamato, powered by 153,553 SHP made 27.46 knots. EHP at this time was calculated at 76,700 hp, the propulsive efficiency at her standard speed of 18 knots proved to be 58.7%. Such efficiency was obtained by only a few vessels of the Japanese Navy.
Another important feature was the extensive use of lap-joints in the midship part of the shell plating. The butt-joint had long been used in shell plating to make the shell surface smooth, thus reducing it's frictional resistance. However a serious defect had been found in the outer bottom butt-joint plates of the Isuzu class light cruisers and Fubuki class destroyers. This led to the apprehension regarding the use of butt-joints on the Yamato's shell plating. On the other hand, it was learned that frictional resistance was greatly affected by the surface of the fore and aft parts of the ship, where the water pressure was greater then amidships. Based on this finding, butt-joints were used in the fore and aft parts of the Yamato; the remaining part was covered by lap-joint plating. The method proved very effective when the ship was completed.

Hull Structure

In the hull structure, too, several new measures were adopted to ensure the required strength and at the same time, save weight:
Here are some examples;
First some of the armor was fitted to serve as hull strength members.
The lower side armor was fitted to serve dually as longitudinal members. This was a unique method that the Japanese Navy had applied to medium armor plating since it was first applied to the Heavy cruiser Furataka, whose characteristics surprised world shipbuilding circles at the time.
Second, electric welding was employed extensively except in the longitude members. The Japanese Navy was rather early in applying welding to the construction of ship's hulls. The 10,000 ton submarine tender Taigei, which was completed in 1934, was the first ship in the Japanese Navy with a completely welded shell.
However, two subsequent disasters, which involved Japanese men of-war led to a thorough investigation of shipbuilding techniques. In March, 1934 a small destroyer capsized in heavy weather, while in September of the following year, two large destroyers broke in two and another sustained heavy damage in rough weather. An extensive and thorough investigation as then carried out. The wisdom of welding was also reviewed, and it was decided not to use welding in such important portions as longitudinal structure members.
Most of the Yamato's upper structure was constructed by means of welding. The largest welded block for the Yamato was 36 feet high and weighed 80 tons. The total length of the welded portions of the Yamato reached 1,521,601 feet and the total number of welding rods used in the construction was 7,507,536. By comparison the total number of rivets was 6,153,030.
Third,the main portion of the longitudinal structure was constructed with Ducol steel, while other portions were built of mild steel.
Fourth, the central longitudinal bulkhead was duplicated as it was to support heavy 7.87 inch thick armored deck plates, 127.62 feet at their greatest breadth. To ensure the reliability of the electric circuits, the central ringman electric circuit ran through the watertight compartment inside the central bulkhead.
Another unique feature was her flush weather deck from bow to stern, giving her an extraordinary appearance for a battleship. The idea was to make the longitudinal members continuos so as to be most effective and at the same time save structural weight. This method had been adopted in building Japanese warships ever since it first applied to the heavy cruiser Furataka.
The Yamato's stern casing , which had to support her heavy 2,490 ton stern portion was an extraordinary one too. Made of cast steel, it weighed 91.3 tons

Maneuverability

The Yamato's turning ability was excellent.
Her tactical diameter, when turned by a maximum rudder angle of 36 degrees at a speed of 26 knots was 2099 feet.
These figures were considered superior when compared to other battleships.
The Yamato had two rudders, the main and auxiliary, instead of the twin-rudder system of ordinary large warships.
Originally it was planned to install two rudders, one each fore and aft, in view of the fact that the German Bismarck finally lost her maneuverability ability due to damage to her rudders .
But the design was later changed so as to install the auxiliary rudder about 49 feet ahead of the main one.
In her trial runs it was discovered that the auxiliary rudder alone was unable to stop the momentum of a turn once started.

Stability And Trim Under Damaged Conditions

Compared with other Japanese battleships, the Yamato was well designed to survive in a damaged condition.
This was well demonstrated in the Yamato's last hours and that of her sister Musashi, although both were eventually sunk.
The Yamato's fore freeboard was 32.8 feet and aft was 20,9 feet .
These figures were remarkable compared with the Nagatos', which was 25.9 feet and 15.7 feet respectively.
Accordingly her reserve buoyancy reached as much as 54,450 tons compared to 29,292 tons for the Nagato.
The Yamato was designed to maintain stability until her heel reached 20 degrees.
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Re: Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 9:56 pm

Propulsion

Boilers: 12 Kanpon boilers
Temperature: 325 degrees C
Turbines: Kanpon geared steam turbines
Shafts: 4
Horsepower: 150,000 shp design (153,553 shp trials)
Endurance: 7,200 NM @ 16 knts
Speed: 27.46 knts max trials
Oil Capacity: 6,300 tons
Machinery Arrangement: The Yamato's 150,000 SHP main machinery was not unique in any way, but it's arrangement in four rows was noteworthy.
The 13,500 hp boilers were arranged in four rows, three in each row, each comprising a single cell.
Three boilers in one row were connected to one of the four turbines which were also installed in four rows. From the standpoint of damage control and protection, this was naturally a most desirable arrangement. However only a vessel of great beam such as the Yamato could possibly have such an arrangement.

How the Yamato improved her shaft horsepower per square meter of engine room can be seen in the following table:

Ship--------SHP--------Engine Room Floor AE(M²)--------SHP/AE
Nagato----82,300--------------516----------------------------158
Yamato--150,000--------------640-----------------------------238
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Re: Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 10:02 pm

Armor

Side: 16.14" (410mm) Vickers with .35" (8.9mm) Ducol steel plate backing
15.74" (400mm) Vickers with .35" (8.9mm) Ducol steel plate backing (hull #110 & 111)
1" (25mm) DS steel at engine rooms (hull #110 & 111)
3" (76mm) ends
6" (152mm) upper belt

Deck: 1.3"-1.9" (33-48.3mm) superstructure deck
7.87" (200mm) MNC main deck
7.48" (190mm) MNC main deck (hull #110 & 111)
3.5" (89mm) second deck

Main Turrets: 25.6" (650mm) faces
15" (381mm) sides

Secondary (155mm mounts): 1" (25mm) NVNC

Barbettes: 21.5" (546mm) sides
21.25" (540mm) sides (hull #110 & 111)

Conning Tower: 19.5" (495.3mm) sides

Watertight Compartments: 1,065 below waterline
82 above armour deck

The Yamato was undoubtedly the most heavily armored man-of-war ever built.
Her vital parts were protected on the sides by 16.141 inch Vickers hardened armor plates capable of withstanding the force of an 18 inch projectile fired at more then 21,872 yards.
Her 7.87 inch MNC deck plates could be penetrated only by a 2,204 pound armor-piercing bomb dropped from a height of 11,154 feet or more.
Even part of the fore and aft uppermost decks other then the armor protected vital part was protected by 1.4 inch to 1.97 inch CNC, the latter sufficient to repel a 550 pound bomb dropped from a dive bomber.
In designing the Yamato's, efforts were made to minimize the length of the vital part that had to be protected by heavy armor plates.

Ship Comparisons
Ship--------Side Armor--------Deck Armor--------Water line armor length/percentage
Yamato--------16.14"-------------7.87"--------------------------------53.5%
Iowa-------------12.1"-------------1.5" main--6" second +1.5"
Nelson----------14.12"-------------6.32"-------------------------------54.7%
Nagato------------------------------------------------------------------63.15%

Thick armor plates around the vital parts were not the only protective features provided on the Yamato.
Her steering engine compartments (the Yamato had two sets of steering apparatus, the main and auxiliary to safeguard her steering ability), were protected by armor as heavy as that given to the other armored portions.
In addition the floors of the Yamato's magazines were protected by 1.96 inch to 3.14 inch armor plates.
These plates extended from the bottoms of the magazines across the watertight compartments inside the double bottom of the shell.

The idea was to protect from the explosion of a torpedo or mine underneath the ship.
Another feature was the perforated armor plates for her funnel uptake protection, chosen in preference to conventional coaming armor.

After careful tests, 14.96 inch armor plating with perforations of 7 inch in diameter was adopted, the total area of the holes being less then 55% of the whole area of the plate. In addition, the inclined surface of the funnel was protected by 1.96 inch armor which would detonate bombs before the exploded on the surface of the perforated plating, from where the output of smoke from 12 boilers escaped. This new method of funnel hole protection resulted in a substantial reduction of the weight of armor.

The percentage of the Yamato's weight used entirely for protection compared with the total tonnage as designed was high. While that of the Nagato was 32.06%, the highest figure among the Japanese warships before the Yamato, that of the Yamato was 34.4%.

Armor Plates

Some important factors should be mentioned in connection with the Yamato's armor plates, which were manufactured after ten years of intensive study on the part of naval technicians. The front and side barbette armor, which had to resist the terrific kinetic energy of an 18 inch projectile having a speed of approximently 1,640 feet per second consisted of 22 inch and 16.17 inch respectively. An extremely hard surface was a requisite for such armor plate, but the ordinary method of cementation was expensive and incapable of giving the result desired for such thick plates. Instead of the cementation method, therefore, a special method was adopted to harden the surface of such thick plates. This new method proved very effective, not only could it harden the portion reaching as thick as 5.5 inches from the surface, but it also greatly reduced the production cost and time.

Theoretically, the resistance of armor plate to a projectile is not uniform. It is least at it's edge, which means the larger a piece of armor plate the greater the resistance that can be expected. The Japanese Navy ignored expense in expanding the necessary facilities to manufacture larger pieces of armor plate for the Yamato's. According to records, about 10 million dollars was spent on expansion of steel-plate manufacturing facilities. The dimensions of a piece of side armor manufactured 19.3 feet by 11.8 feet, 69 square feet, 16.14 inch thick and weighing 68.5 tons.

How to construct a sufficiently strong armor shelf; especially at the lower edge of the 16.14 inch side armor, to resist the shock of a projectile hit, was a big problem too. The Yamato's side armor was equipped so as to drive a wedge with the wedge angle at 10 degrees at it's lowest edge, when struck by the shock of a direct hit, but even this method proved insufficient after she was commissioned in to service. In the war, she was hit by a torpedo and her side armor at the point of impact was indented about 3 feet. another feature of the armor protection was the 0.35 inch Ducol steel plates which extended along 27 inches underneath the armor deck. Their purpose was to afford protection from possible splinters such as armor bolts and rivet heads when the armor deck was hit by an enemy bomb or projectile.

Watertight Compartments

Much attention was also directed towards the maintenance of buoyancy by increasing the number of watertight compartments. The Yamato had 1147 watertight compartments; 1065 below the armor deck and 82 above. The Nagato's had 1089; 865 below and 224 above.
The reason for fewer for fewer above the armored deck as compared to other ships was the fact that the Yamato's armored deck was comparatively high above the waterline.

Flooding & Pumping Systems

The flooding and pumping system of the Yamato's was designed to satisfy the following requirements:
1) The heel and trim resulting from the first torpedo hit could be rectified within 4 degrees heel and 7.5 feet draft difference between the fore and aft within five minutes after the damage control system was started.
2) The heel and trim resulting from the second torpedo hit could be controlled within 30 minutes by the same standards
By flooding the damage control tanks on the opposite side, the Yamato could also be righted by 13.8 degrees maximum and another 4.5 degrees of heel could be added by shifting fuel to the opposite tanks. It was believed that this system could enable the Yamato to return to almost even keel from a list of 18.3 degrees.
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minoru genda
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Re: Yamato Class Battleships

Postby minoru genda » Mon Mar 02, 2009 10:07 pm

Armament

Main Battery: 9 x 18.1"/45 cal Model 1934 in three triple turrets. 2 forward 1 aft

Secondary:
12 x 6.1" (155mm)/60 cal Model 1914 in 4 triple turrets (design)
1 forward, 1 aft, 1 port mid, 1 starboard mid
the 2 midship turrets were removed by 1944
12 x 5" (127mm)/40 cal Model 1928 in 6 twin mounts (design)
24 x 5" (127mm)/40 cal Model 1928 in 12 twin turrets (Apr./44 Yamato)

AAW:
24 x 25mm/60 cal AA in 8 triple mounts(design)
72 x 25mm/60 cal AA in 24 triple mounts (Apr./44 Yamato)
96 x 25mm/60 cal AA in 32 triple mounts (Apr./44 Musashi)
87 x 25mm/60 cal AA in 29 triple mounts (Jun./44 Yamato)
146 x 25mm/60 cal AA in 41 triple & 23 single mounts (May./45 Yamato)
4 x 13mm MG (design) removed Apr./44

Main Armament

The Yamato's main armament consisted of nine 18.1 inch guns/45 caliber's in length mounted in three triple turrets, the first triple mounting designed by the Japanese navy following the triple 6.1 inch turret designed for the Mogami class cruisers. No. 1 and No.2 turrets were mounted forward, with No.2 superimposed while No.3 turret was mounted aft.
This arrangement of the main armament was decided after various studies with the main aim of reducing the weight of protection as much as possible.
Moreover her undulating flush weather deck which was lowest in front of turret No.1, made it possible to lower the height of those turrets considerably, thus contributing to overall stability.
For the secondary armament, the Japanese navy decided to mount four triple turrets of 6.1 inch/55 caliber guns. Two of them were mounted on the centerline, one aft of No.2 main turret and one forward of No.3 main turret., while the remaining two were installed on both sides amidships.
These 6.1 inch turrets had originally been installed on board the Mogami class light cruisers and were removed from them when their main armament was changed to 8 inch guns.
This makeshift measure of employing 6.1 inch gun turrets from light cruisers proved to be a major defect. The 6.1 turrets had only the protection of a light cruiser's turrets.
The two amidships turrets were removed later on to make way for more AA weaponry.
The Yamato's AA weaponry consisted of six twin 5 inch (127mm) guns, three on each side, eight triple .98 inch (25 mm) AA machine guns four on each side and two twin 0.50 inch (13mm) machine guns one on either side of the the mainmast. This was increased substantially during her's and the Musashi's careers.

Terrific Blast Of The 18" Guns

Terrific effects were anticipated on numerous installations aboard the Yamato from gun blast.
While the blast of two 16 inch guns simultaneously firing was reckoned at 19.58 pounds/per square inch at a point 5.9 inch from the gun muzzles, that of the Yamato's three 18 inch guns was approximately 58 pounds/ per square inch.
This was an immense figure , since it was believed that the blast pressure of 1.5 pounds per square inch was capable of destroying boats on board the ship and that 6.49 pounds per square inch was capable of tearing the cloths from men and renduring them temporally unconscious.
This meant that nowhere on her weather deck would any boat be safe while her main battery was firing;
AA guns as well as AA machine guns had to be protected by shields from the blast.
Vedette boats, other launches and cutters were to be kept inside the boat hangars which were installed on both sides of the stern.
Ventilators on the weather deck were reduced to a minimum and installed at places where the blast was least effective.
The idea of protecting the AA batteries from the blast by shields, enabling them to fire while the main batteries were in use, greatly restricted the installation anti-aircraft weapons.
After the outbreak of war, however the importance of powerful AA weapons was keenly and later bitterly, realized.
This restriction had to be lifted so that many AA machine guns were installed on the weather deck without a shield to protect them from the blast.

Radars
Surface Search: Type 21 15cm Range Finders
Air Search: N/A
Navigation: N/A
Fire Control: N/A

The Yamato and Musashi were commissioned without any radar sets.
Unlike the ugly "pagoda" masts which had been traditional features of Japanese battleships, the Yamato's tower foremast was much improved and streamlined.
It's frontal and side areas were 521.65 square feet and 1,017 square feet respectively.
The Tower consisted of two concentric cylinders on top of which were large triple 49 foot range finders (one of which was of the inverted stereoscopic image type) and the main armament director.
Precautions were also taken to protect the nerve-center of the ship from strafing of enemy planes.
The inner cylinder 4.9 feet in diameter was made from 20mm DS steel, inside of which ran communications lines.
Space between the outer and inner cylinders was utilized for passages, staff briefing rooms etc.

Aircraft

Fixed Wing:
2 E13A1 Aichi "Jakes"
2 F1M2 Mitsubushi "Petes"
4 max carried
2 catapults aft

Complement

Design: 2200
Wartime: 2500+
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Re: Yamato Class Battleships

Postby Legend » Tue Mar 03, 2009 4:21 am

Very interesting! It's a full detailed summary of the two ships, though I am surprised that there is no arguments here... I am so used to you guys bickering instead of just posting the obvious for the benefit of others. I compliment you.
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Re: Yamato Class Battleships

Postby JtD » Tue Mar 03, 2009 6:51 am

I've always wondered if there were any differences between Yamato and Musashi as completed. Does anyone know?

And Pagoda masts aren't ugly, they are beautiful.

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minoru genda
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Re: Yamato Class Battleships

Postby minoru genda » Tue Mar 03, 2009 1:40 pm

Let me tell you that I'm not the author of that article and I don't know who wrote it.
I saved it on my computer many years ago and wanted to share with you all.
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Re: Yamato Class Battleships

Postby José M. Rico » Tue Mar 03, 2009 3:01 pm

minoru genda wrote:Radars
Surface Search: Type 21 15cm Range Finders
Air Search: N/A
Navigation: N/A
Fire Control: N/A

The Yamato and Musashi were commissioned without any radar sets.
Unlike the ugly "pagoda" masts which had been traditional features of Japanese battleships, the Yamato's tower foremast was much improved and streamlined.
It's frontal and side areas were 521.65 square feet and 1,017 square feet respectively.
The Tower consisted of two concentric cylinders on top of which were large triple 49 foot range finders (one of which was of the inverted stereoscopic image type) and the main armament director.
Precautions were also taken to protect the nerve-center of the ship from strafing of enemy planes.
The inner cylinder 4.9 feet in diameter was made from 20mm DS steel, inside of which ran communications lines.
Space between the outer and inner cylinders was utilized for passages, staff briefing rooms etc.


There is some good information about Yamato's radars here:

viewtopic.php?f=13&t=1737

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Re: Yamato Class Battleships

Postby Bgile » Tue Mar 03, 2009 3:21 pm

The only thing I noticed was the Yamato magazine explosion is listed as being in the "No 1" magazine. I'm not sure what that means, but I'm reasonably certain it was the aft magazine which exploded. I could be wrong, but I am thinking the after 6.1" turret was destroyed by a bomb and the fire there was never put out, and some people have hypothesized that was the cause of the magazine explosion. I think the condition of the wreck supports this.

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Re: Yamato Class Battleships

Postby lwd » Tue Mar 03, 2009 3:21 pm

minoru genda wrote: .... These great ships were built in complete secrecy and it was not until very late in the war that it was found out how large and powerful they really were....

There's a good article about that here:
http://www.navweaps.com/index_tech/tech-084.htm


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