Japan's Light/Heavy Cruiser Mogami

[Tanz]

Well I’m back at it  :eyesup: . After being in Yokosuka, I had time to think about what ship to do a thread on. So, I went with a ship that everyone knows about. A very popular and well know ship.

 

HIJMS Mogami

 

The Mogami was one of a class of four IJN Cruisers (Mogami, Mikuma, Suzuya and Kumano) built in the mid-thirties, & was the lead ship of her class of cruisers.

 

In the late twenties and early thirties, the Imperial Japanese Navy built a series of eight very large and powerfully armed "Type A" (heavy) cruisers, the four Takaos, and the four Nachi. The Mogami class was a design continuation of these ships in style and layout, differing only in the type of armament specified. They were in fact designed from the beginning to be able to be upgraded to 8" gun ships should the political situation allow it. It should be noted that all of these ships were looked upon with considerable suspicion in the West as it was stated by both American and British naval constructors that the TAKAO and NACHI class HAD to be exceeding treaty limits in displacement. When trying to design an equally powerful reply they found it impossible to arrive at the same combination of armor, armament and size and still remain within the 10,000 ton limit. Although officially denied, the Japanese ships were in fact well in excess of the legal treaty limits.

 

Construction

 

She was laid down on October 27th, 1931 in the Kure Yards, launched on March 14th, 1934 and commissioned into the Fleet in July 1935.

 

The Mogami when built weighed in around 13,400 tons (which was not even the largest Japanese cruiser displacement at the time).  Even with the extra displacement, she was overloaded. Major efforts were made to keep displacement down. Several innovations were tried to reduce weight and attempt to comply with the treaty limitations but without sacrificing any fighting power. Electric welding was used extensively in their construction, a pioneering effort that resulted in serious structural weakness. All of the boiler uptakes were trunked into a large single funnel. After the capsizing of the torpedo boat TOMODZURO during a fleet exercise, the design was revised and top weight was drastically reduced. The original massive bridge, (similar to the TAKAO), as designed for the class was discarded and a new more compact design was built. In spite of these changes the Mogami was still too heavy and was well over the treaty specifications.

 

 

The weight saving attempt by using electric welding in the construction of Mogami resulted in a serious weakness. After her high speed trials the hull was found to have suffered warpage, the bow was twisted and the main turrets forward could not be trained. While the hull was of a very light construction, there was a very heavy armament and the result was nearly a major disaster. She was completely overloaded.  During trials it was discovered that stability was dangerously poor. She had busted weld seams when she fired all of her main battery guns simultaneously.  It was so bad that Mogami and Mikuma were both drydocked for extensive reinforcement. Kumano and Suzuya were redesigned as a result of the problems encountered in the first two sisters.

 

Originally armed with 15 6in(155mm) guns in five triple turrets (and rated by the west as "Light Cruisers", they were re-armed (this was planned for in the design as the 6 inch turret rings were the same size as the 8 inch turret rings) after completion (when the treaty limiting the number of 8 inch gunned ships expired) with 10 8 in(203mm) guns in twin turrets. So she went from being a Light Cruiser to a Heavy Cruiser.

 

 

 

 

Service Life

 

In early 1941, Mogami participated in the occupation of Cochinchina, French Indochina, from its forward operating base on Hainan after Japan and Vichy French authorities reached an understanding on use of air facilities and harbors from July 1941. At the time of the attack on Pearl Harbor, Mogami was assigned to cover the invasion of Malaya as part of Cruiser Division 7 under Vice Admiral Jisaburo Ozawa's First Southern Expeditionary Fleet, providing close support for landings of Japanese troops at Singora, Patani and Kota Bharu.

 

In December 1941, Mogami was tasked with the invasion of Sarawak, together with Mikuma, covering landings of Japanese troops at Kuching. In February 1942, Mogami was assigned to cover the landings of Japanese troops in Java, Borneo and Sumatra. On 10 February, Mogami and Chokai were attacked by USS Searaven, which fired four torpedoes, all of which missed.

 

The Battle of Sunda Strait

 

At 2300 on 28 February 1942, Mikuma and Mogami, destroyer Shikinami, light cruiser Natori and destroyers Shirakumo, Murakumo, Shirayuki, Hatsuyuki and Asakaze engaged USS Houston and HMAS Perth with gunfire and torpedoes after the Allied vessels attacked Japanese transports in the Sunda Strait. Both Houston and Perth were sunk during the engagement, as was Japanese transport Ryujo Maru with IJA 16th Army commander Lieutenant General Hitoshi Imamura.

 

 

 

 

Not only had the Japanese sank both Allied ships but managed to sink five of their own ships.

 

In March of 1942, Mogami and Cruiser Division 7 were based out of Singapore to cover Japanese landings in Sumatra and the seizure of the Andaman Islands.

 

Battle of Midway

 

 

Admiral Yamamoto was still attempting to digest the calamity that had befallen Admiral Nagumo’s carrier task force. His Staff was hastily attempting to arrive at a solution which might reverse the disaster and bring victory.  Admiral Ugaki, Yamamoto’s Chief of Staff despite his personal doubts ordered Vice Admiral Nobutake Kondo to prepare for a night surface engagement with the US Fleet and to dispatch a strong surface force to bombard Midway in order to prevent the Americans from reinforcing it and to prevent its further use against his forces should the invasion move forward.  Kondo organized his fleet to attempt to find the American carriers and bring them to battle before dawn.

 

Kondo detached Vice Admiral Takeo Kurita’s Close Support Group composed of Cruiser Division 7 to shell Midway Island in preparation for a Japanese landing. Cruiser Division 7 and Destroyer Division 8 were 410 miles (660 km) away from the island, so they made a high-speed dash.

 

 

 

 

Kurita’s force was 80 miles from Midway when Yamamoto realizing that his plan was unrealistic ordered Kondo’s forces to retreat and rendezvous with his main force shortly after midnight. The order was met with a measure of relief by most officers in the force and the ships turned northwest and steamed at 28 knots to meet the Main Body.

However, the force had been spotted and was being shadowed by the submarine USS Tambor. At 0215 lookouts on Kumano sighted a submarine on the surface. Kumano signaled a 45° simultaneous turn to starboard to avoid possible torpedoes.

 

During emergency maneuvers Mogami’s Navigator took over from the watch to oversee the tricky maneuver. In doing so he thought that there was too much distance between him and the ship ahead, the Mikuma. So he adjusted his course to starboard and then realized his mistake. The ship he thought was Mikuma was actually Suzuya and Mikuma was directly ahead. As soon as he recognized his mistake Mogami’s Navigator ordered a hard turn to port and reversed the engines but it was too late. Mogami’s bow crashed into Mikuma’s port quarter. The impact caused minimal damage to Mikuma but Mogami was heavily damaged. She lost 40 feet of her bow and everything else was bent back to port at right angles to her number one turret.

 

Mogami managed to rupture Mikuma's fuel tank, causing her to leave a trail of oil in her wake. Mogami’s damage control teams isolated the damage and worked the ship up to 12 knots. This was not fast enough for Kurita to make his rendezvous, and even though Mikuma was capable of steaming at high speed he left her and the destroyers to escort Mogami while he steamed ahead with Kumano and Suzuya.

 

Tambor’s skipper LCDR John W Murphy sent a contact report at 0300 reporting “many unidentified ships.” He followed this with more detailed information and the Americans on Midway began to launch its remaining serviceable aircraft to attack the threat.

 

A flight of B-17 Bombers launched at 0430 could not find the Japanese ships but at 0630 a PBY Catalina found the Japanese and radioed Midway “two Japanese battleships streaming oil.”

 

The remaining 12 aircraft of VSMB-241 under command of Captain Marshall Tyler a mix of SBD Dauntless and SB2U Vindicators took off at 0700. His force attacked at 0808 scoring no hits. The two ships limped northwest at 12 knots escorted by the destroyers and were unmolested through much of the day with the exception of an ineffective attack by the B-17s at 0830.

 

The following morning on 6 Jun 1942, aircraft from American carriers Enterprise and Hornet sent three attack waves against the two damaged cruisers. US Dive Bombers attacked the cruisers throughout the morning and into the afternoon. Mogami was hit by six bombs, one bomb on the seaplane deck and started a serious fire, killing a number of crewmen, including many wounded in the sick bay. Her No. 5 turret was destroyed and 81 crewmen were killed.  The escorting destroyer were also hit but survived.

Mogami was saved by the skill of her damage control teams and the foresight of her Damage Control Officer to jettison her torpedoes so that they did not explode and compound the damage wrought by the American bombs.

 

In contrast to her sister ship Mikuma it was one of the critical differences that led to Mogami's successful escape from battle and Mikuma's sinking. Mikuma was hit by at least five bombs and set afire. Her torpedoes ignited and the resultant explosions destroyed the ship.

 

 

 

 

The action against the cruisers ended the combat operations at Midway. The Japanese ships were doomed by Yamamoto’s decision to try to salvage victory from defeat.

For the Americans it was a fitting end to the Battle of Midway and revenge for the Battle of the Sunda Strait where Mikuma and Mogami sank the USS Houston.

 

Reconstruction/Conversion

 

Following Midawy, Mogami was out of the war for 10 months.  She rejoined Cruiser Division 7 on June 8th and was repaired at Truk. On 20 June, Rear Admiral Shoji Nishimura assumed command of Cruiser Division 7, and the Division was transferred to the Third Fleet. Mogami returned to Sasebo Japan in August, and underwent a major conversion.

She was converted into an aircraft cruiser to improve the fleet's reconnaissance capabilities. Her No. 4 turret and the damaged No. 5 turret were removed and her aft magazines modified to serve as gasoline tanks and munitions storage. Her aft deck was extended and fitted with a rail system to accommodate the planned stowage of 11 Aichi E16A Zuiun ("Paul") reconnaissance floatplanes. The dual 25-mm AA guns and 13-mm machine guns were replaced by 10 triple mount Type 96 25 mm AT/AA Guns and a Type 21 air-search radar. As the new E16A aircraft were not yet available, three older Mitsubishi F1M2 Type 0 ("Pete") two-seat biplanes and four Aichi E13A1 Type O ("Jake") three-seat reconnaissance floatplanes were embarked. Rebuilding was completed on 30 April 1943, and Mogami was re-commissioned into the First Fleet.

 

 

 

 

On 22 May, Mogami collided with oiler Toa Maru in Tokyo Bay and was damaged slightly. On 8 June, while at Hashirajima, Mogami was moored near the Mutsu when the latter exploded and sank. Mogami sent boats to rescue survivors, but they found none.

 

On 9 July 1943, Mogami departed Japan for Truk, with a major convoy of troops and supplies; the task force was unsuccessfully attacked by USS Tinosa, and after reaching Truk, continued on to Rabaul.

 

From August through November, Mogami made numerous sorties from its base at Truk in search of the American fleet and in response to American probing attacks into the Marshall Islands. From 3 November, Cruiser Divisions 4, 7 and 8 were assigned to the Solomon Islands front, to attack American forces off Bougainville. While at anchor at Rabaul on 5 November, Mogami was attacked by a SBD Dauntless dive-bomber from USS Saratoga and hit by a 500-lb. bomb. She was set on fire and 19 crewmen were killed.

 

After repairs at Truk, Mogami was ordered back to Japan. While at Kure eight Type 96 single-mount 25-mm AA guns were installed on the aft deck, bringing the total to 38 barrels. Refit was completed by March 8th, 1944, and Mogami returned to Singapore a week later.

 

Battle of the Philippine Sea

 

On 13 June 1944, Admiral Soemu Toyoda, CINC, Combined Fleet, activated the "A-Go" plan for the defense of the Mariana Islands. Mogami was assigned to Rear Admiral Takatsugu Jojima's "Force B" with the carriers Junyo, Hiyo and Ryuho and battleship Nagato, deployed behind Vice Admiral Kurita's "Vanguard Force C".

 

At 0530 Mogami launched two reconnaissance floatplanes. Later in the day, the Mobile Fleet's aircraft attacked Task Force 58 off Saipan, but suffered overwhelming losses in the "Great Marianas Turkey Shoot". At 2030 on 20 June, two hours after she was hit by torpedoes by Grumman TBM Avengers from USS Belleau Wood, the Hiyo exploded and sank. That night, Mogami retired with the remnants of the Japanese fleet to Okinawa.

 

Back in Kure on 25 June 1944, Mogami was refit once again. Four triple-mount and 10 single-mount Type 96 25-mm AA guns were installed, bringing the total to 60 barrels (14x3 and 18x1) and a Type 22 surface search radar and Type 13 air-search radar were fitted. On 8 July, Mogami departed Kure back for Singapore and Brunei, and was involved in fleet training and patrols in the Singapore-Brunei area through October.

 

Battle of Leyte Gulf

 

In late October, the Japanese fleet assembled in Brunei in response to the threatened American invasion of the Philippines. In the morning of 24 October 1944, Vice Admiral Nishimura ordered the launch of Mogami's floatplane to reconnoiter Leyte Gulf. The plane reported sighting four battleships, two cruisers and about 80 transports off the landing area and four destroyers and several torpedo boats near Surigao Strait. In addition, the scout reported 12 carriers and 10 destroyers 40 miles (64 km) southeast of Leyte. The Japanese task force was attacked in the Sulu Sea by 26 aircraft from USS Enterprise and Franklin. Mogami was damaged slightly by strafing and rockets.

 

Battle of the Surigao Strait

 

On 25 October, between 0300-0330, the Japanese force was attacked by American PT boats and destroyers. Battleships Fuso and Yamashiro were hit by torpedoes and destroyers Yamagumo was sunk, and Michishio disabled, but Mogami was not hit. Fuso and Yamashiro both later exploded and sank. Between 0350-0402, after entering the Surigao Strait, Mogami was struck by four 8-inch (200 mm) shells, which destroyed both the bridge and the air defense center. Both the captain and executive officer were killed on the bridge, and the chief gunnery officer assumed command.

 

 

 

 

While attempting to retire southward, the flagship Nachi collided with Mogami. Nachi's bow was damaged and she began to flood. Mogami was holed starboard above the waterline, but fires ignited five torpedoes that exploded and disabled her starboard engine.

 

 

 

 

Between 0530-0535, the crippled Mogami was hit again by ten to twenty 6-inch and 8-inch shells from USS Portland, USS Louisville and USS Denver. At 0830, Mogami's port engine broke down. At 0902, while adrift, she was attacked by 17 TBF Avenger torpedo-bombers from Task Group 77.4.1 and was hit by two 500-lb. bombs. At 1047, Mogami's crew abandoned ship, and she stayed afloat for the next 2 hours. At 1240, Akebono scuttled her with a single Type 93 "Long Lance" torpedo.

 

She finally sank at 1307, at 09°40′N 124°50′E. Akebono rescued 700 survivors, but 192 crewmen perished with the ship.

 

HIJMS Mogami

 

General Specifications

 

Displacement:

8,500 tons (official, initial)

13,670 tons (final)

 

Length:

661 ft 5in...201.6 m

 

Beam:

67ft 7in...20.6 m

 

Draught:

5.5 meters (initial)

5.89 meters (final)

 

Propulsion:

4-shaft geared turbines

10 Kampon boilers

152,000shp

 

Bunkerage: 2215-2302 tons of fuel oil

 

Speed:

37 knots (initial)

35 knots (final)

 

Range: 8,000 nmi (15,000 km) @ 14 knots (26 km/h)

 

Complement: 850

 

Armament:

Light Cruiser

15 × 155mm/60-cal guns(5x3)

8 × 127mm/40-cal guns(4x2)

4 x 40mmAA guns

12 × 610mm torpedo tubes

 

Heavy Cruiser/Carrier Conversion

6 × 20 cm/50 3rd Year Type naval guns (3x2)

8 × 127mm/40-cal guns(4x2)

30 x 25mmAA guns

12 × 610mm torpedo tubes

 

Armor:

Main Belt: 3.9in - 4.9in (100mm -124mm)

Decks: 1.4in - 2.4in (35mm - 61mm)

Barbettes: 1in (25 mm

Turrets: 1in (25mm)

Bridge: 3.9in (100mm)

 

Aircraft carried

2 Catapults

3 x floatplanes for Original design

After Conversion: 11 floatplanes

 

Please feel free to add any additional information or corrections. While doing this one I noticed that sources vary on actual spec & a few other things :amazed:. Yet while the Class is very popular, there not that many photos of the Mogami herself in battle :sad:.

Enjoy the read  :popcorn:

[JeeWeeJ]

Awesome work as usual Tanz! :Smile_great:

[madmanthan21]

JeeWeeJ, on 30 November 2012 - 09:56 AM, said:

Awesome work as usual Tanz! :Smile_great:

Exactly, very good read and nice pics

[alphakaynine]

With this and the post before it took me about a half an hour but a good 30 mins.

[sgtpepper500]

awesome post! :Smile_great:

[AceF]

Mogami plus Brooklyn will be the ship I use. I love cruisers with loads of mediumsized guns, perfect boat to violate those disgusting destroyers ;)

[Haguro]

Great post as usual Tanz... :Smile_great:

 

Mogami seems like an unlucky ship.  Rams her sister ship Mikuma at Midway, hits the Toa Maru in Tokyo Bay, and then manages to find a way to get in Nachi's way after Surgiao Strait.  Let hope those that use this class in WOW have better luck. :Smile_amazed:

 

http://www.njipms.or...hip_mogami2.jpg

http://www.history.n...000/g457861.jpg

Toa Maru

http://www.combinedfleet.com/Toa2.jpg

IJN Nachi

http://www.combinedfleet.com/Nachi.jpg

[Tanz]

Haguro, on 30 November 2012 - 08:34 PM, said:

Great post as usual Tanz... :Smile_great:

Mogami seems like an unlucky ship.  Rams her sister ship Mikuma at Midway, hits the Toa Maru in Tokyo Bay, and then manages to find a way to get in Nachi's way after Surgiao Strait.  Let hope those that use this class in WOW have better luck. :Smile_amazed:

http://www.njipms.or...hip_mogami2.jpg
http://www.history.n...000/g457861.jpg
Toa Maru
http://www.combinedfleet.com/Toa2.jpg
IJN Nachi
http://www.combinedfleet.com/Nachi.jpg

Hey Haguro....Yeah..that's one thing I noticed about her  :Smile_amazed:. she kept ramming into other ships  :Smile_amazed:

[_Jeremiah_Gottwald]

Glad to hear you're home safe and sound mate  :Smile_honoring:

 

Now it won't be just me posting long threads about ships anymore  :Smile_veryhappy:

[Super_Dreadnought]

Great work +1

 

I hate the 1943 refit though.Seeing all those planes on deck feels 'not right', why the need for 7 scout planes? The original design was ruined, just ruined.

[lexica]

It kinda had been their only option though, not like their main batteries would be of a lot use anyway... I personally do like the refit, to me it brought a balanced and uniquely futuristic look to the ship

[Haguro]

To add to IJN Mogami's saga, as mentioned by Tanz, at the Battle of Sunda Strait, Mogami torpedoes were found to be the culprit in sinking 5 Japanese ships.  The victims were:

1. Sakura Maru (7,149 tons)

http://www.combinedf...m/Sakitowar.jpg

2. Horai Maru (9,162 tons) - Reportedly acting as a hospital ship

http://www.photoship...rai Maru-02.jpg

3. Tatsumo Maru (6,960 tons) [some reports state this ship ran aground to avoid torpedoes, however, as the torpedoes were almost wakeless and this was a night action, this might be a stretch]

http://www.combinedf...com/tatsuno.jpg

4. Shinshu Maru (8,160 tons) actually an Army Special Transport also known as Ryujo Maru

http://www.combinedf...om/Shinshu2.jpg

5. IJN Minesweeper W-2 (one can only imagine the damage done to a small minesweeper by a Type 93 torpedo) :Smile_sad:

http://www.combinedfleet.com/W-2.jpg

Here again IJN Mogami proves herself to be an unlucky ship.  5 of 6 torpedoes hit your own ships (the ultimate teamkiller) :Smile_ohmy:

The torpedoes took 8 minutes to hit the ships from a range of 11,800 meters (12,905 yards).

[Tanz]

Haguro, on 02 December 2012 - 03:02 PM, said:

To add to IJN Mogami's saga, as mentioned by Tanz, at the Battle of Sunda Strait, Mogami torpedoes were found to be the culprit in sinking 5 Japanese ships.  The victims were:
1. Sakura Maru (7,149 tons)
http://www.combinedf...m/Sakitowar.jpg
2. Horai Maru (9,162 tons) - Reportedly acting as a hospital ship
http://www.photoship...rai Maru-02.jpg
3. Tatsumo Maru (6,960 tons) [some reports state this ship ran aground to avoid torpedoes, however, as the torpedoes were almost wakeless and this was a night action, this might be a stretch]
http://www.combinedf...com/tatsuno.jpg
4. Shinshu Maru (8,160 tons) actually an Army Special Transport also known as Ryujo Maru
http://www.combinedf...om/Shinshu2.jpg
5. IJN Minesweeper W-2 (one can only imagine the damage done to a small minesweeper by a Type 93 torpedo) :Smile_sad:
http://www.combinedfleet.com/W-2.jpg
Here again IJN Mogami proves herself to be an unlucky ship.  5 of 6 torpedoes hit your own ships (the ultimate teamkiller) :Smile_ohmy:
The torpedoes took 8 minutes to hit the ships from a range of 11,800 meters (12,905 yards).

Thanks for adding that Haguro  :Smile_honoring:. Totally is the ultimate teamkiller  :Smile_veryhappy:  :Smile_ohmy:

[anonym_auUiRfWCi1jI]

Excellent OP!  Simply, Wow!  Thoroughly enjoy the component views, level of detail shown, and the pics.  Good work.

[Wunderwaffen1945]

One of the best ship of its' class

[Wiscoo]

Great post. As for history - wth was wrong with those Japanese navy, that they hit each other so many times...?

[NGTM_1R]

Deadnought, on 02 December 2012 - 01:15 AM, said:

I hate the 1943 refit though.Seeing all those planes on deck feels 'not right', why the need for 7 scout planes? The original design was ruined, just ruined.

I've actually always wondered why they could only fit seven. The class already had room for three and while admittedly the Tones, purpose-designed for it, only carried five, it seems like there's more room back there than that...

[Haguro]

Quote

I've actually always wondered why they could only fit seven. The class already had room for three and while admittedly the Tones, purpose-designed for it, only carried five, it seems like there's more room back there than that...   

From the drawings and models of the Tone class and the modified Mogami, it would seem that Mogami's aircraft carrying deck is all on one level.  The Tone class aircraft carrying capability is located on two decks. Also Mogami only carried three turrets that allowed her superstructure to be located further forward vs. the Tone class that had four turrets, forcing the main super structure further back reducing some of the ability to carry aircraft.  At least one Japanese model maker seems to agree with your assumption.



http://www.tamiya.co...1mogami/top.jpg

http://www.combinedf...com/mogami2.jpg






http://www.the-bluep...y-cruiser-2.png

[Azumazi]

I had to bump this thread, because one thing that drives me nuts about the Wiki link, is the armor values are mostly wrong (It lists the pre-modernization and not the post like most usually do). So I had to go digging around trying to find some of the data I had that was in Japanese but already in English, and I found one of my books that lists a little bit of the changes.

 

The armor for the turrets is for the 155mm (Not the 8 inch guns) and most of the armor is listed for the CL version and without the upgrades so thought I would at least list them down here as I find them in some of my books and will list the references. (Bold for the TL:DR people)

 

Ref: Ships of World War 2; John Ward

Super Illustration IJN Cruiser Mogami ; Isbn code : 4910087340417 (This book is in Japanese Only)

 

8 Inch Turrets (127mm Forward, 76.2mm Top, 25mm Rear and Sides)

Barbettes 75mm for Turrets A, B, E ; 100mm for C, D

 

 

The Turrets had 127mm in the front of the turret, the 76.2mm is for the sides and 25mm for the rear of the turret to save weight (It was the same turrets as the Myoko with slight modifications) as they expected to have the turrets facing the enemy while in combat; however, we all know how well that works in reality. The barbettes were 75mm for the lower turrets and 100mm for the raised turrets with a portion of it tapering to 25mm at the turret ring and the machinery from where the turret sat on it roughly 20cm down (This was a problem in design that would allow a shell to pen under the turret and detonate amazingly I don't believe it ever happened). After it was uparmored with the bulges added, they also added additional armor on the mid section belt, and uparmored the decks near turret B, C, through to the conning tower to 60mm-62mm (Hence the 2.4 inch sections) and all the way back to the E turret taping down.

 

I remember they did something else to the ship but I can't remember what it was and still sifting through books at the moment. I know had I had one that showed a much better layout of its armor.

 

(Edited, had the Top and Sides mixed in turret profile)

[Azumazi]

Okay I usually don't double post, but after getting some info from another forum I know through their sources (I would usually just edit it in if I was the OP since its the first post on the page.)

 

The 8 inch turrets had different armor for the original refit, and the 1944 to CV refit did some changes to the turrets as well. It seems that originally the Myoko's turrets were to be 5.9" faces, 3.9" roofs and 2" sides and rear, and kits were designed to take them to that armor thickness. Since the Turrets were just slightly redesigned for the 8inch guns in the Mogami and Tone from the Takao, they were also able to fit this armor, however it wasn't originally placed on the ships due to the weight making it top heavy (THE ORIGINAL PROBLEM). The only ship in the Mogami class to receive these armor specs were the Mogami herself when they removed the rear 2 turrets and converted it into a CV deck. The armor added roughly 50 tons of armor per turret, adding 150 tons to the forward section balanced by the rear section's hanger bays.

 

1944 Refit

8 Inch Turrets: 5.9 inches/150mm Front, 3.9 inch/99mm Roof/Top, 2 Inch/50mm Sides and Rear

 

Being that they were designed, it would be safe to say that WG could make them into an upgraded turret selection for the Myoko (Original kit designed for them) for their 7.9 Inch Guns, Mogami, and Tone. The Tone because it was designed with the same upgrades as the Mogami in mind.

[Gigaton]

The 25mm or 1 inch turret protection on Japanese heavy cruisers isn't just a Wiki thing, it's repeated in every English language source I have read. Interesting if true though, as is the uparmouring of turrets for the hybrid Mogami (though the turrets have somewhat different dimensions than those of Myôkos, being slightly longer and taller). However, Lacroix gives 25mm NVNC for both the 6.1-in and 8-in turrets of Mogami, and doesn't seem to note anything of uparmouring for the hybrid.

 

Also according to Lacroix, the 75mm and 75-100mm parts are not the barbettes (which should be 25mm), but are additional armoured rings that protect the trunks of the turrets for some distance above the lower deck (armoured deck above magazines) 1.5 meters high for the lower turrets and 2.5 for the superfiring ones. The 60mm part of the armoured deck you mentioned is for the sloped outboard areas of the machinery deck, which is effectively a turtle back deck (similar to Yamato, which has 230mm MNC instead of 200mm for these outboard areas).

 

During the Second Efficiency Improvement Works (ie. the hull strengthening) additional D-steel plating was added, but this isn't really uparmouring. D-steel (main structural steel used in the hull) is a semi-armour grade material though (British Royal Navy used it extensively for deck protection on cruisers) so the additional plating does offer modicum of additional protection as byproduct.

[anonym_s4TCbLNuhWyC]

Great Looking ship and so is the Tone Class Also by the title this is a Heavy Cruiser Not A light But great post overall :D +1

[Azumazi]

Gigaton, on 13 February 2013 - 10:37 PM, said:

The 25mm or 1 inch turret protection on Japanese heavy cruisers isn't just a Wiki thing, it's repeated in every English language source I have read. Interesting if true though, as is the uparmouring of turrets for the hybrid Mogami (though the turrets have somewhat different dimensions than those of Myôkos, being slightly longer and taller). However, Lacroix gives 25mm NVNC for both the 6.1-in and 8-in turrets of Mogami, and doesn't seem to note anything of uparmouring for the hybrid.

Also according to Lacroix, the 75mm and 75-100mm parts are not the barbettes (which should be 25mm), but are additional armoured rings that protect the trunks of the turrets for some distance above the lower deck (armoured deck above magazines) 1.5 meters high for the lower turrets and 2.5 for the superfiring ones. The 60mm part of the armoured deck you mentioned is for the sloped outboard areas of the machinery deck, which is effectively a turtle back deck (similar to Yamato, which has 230mm MNC instead of 200mm for these outboard areas).

During the Second Efficiency Improvement Works (ie. the hull strengthening) additional D-steel plating was added, but this isn't really uparmouring. D-steel (main structural steel used in the hull) is a semi-armour grade material though (British Royal Navy used it extensively for deck protection on cruisers) so the additional plating does offer modicum of additional protection as byproduct.

Yeah I didn't mention the sleeve since it confuses most people, but yes you're right its basically a wrap around, Hence why there is a slight gap on it from the ring (the weak point I mentioned).

The 25mm is correct for the whole turret of the 6.1, The Takao also has the same armor on it for the 8 inch guns to save weight, and originally they were going with it for the Mogami due to the Top heavy weight. As for the different Dimensions, it was the same overall style, and I still don't know why they didn't do a remodel on the Myoko to fit them on it (Doing a slight hull extension to widen the hull and putting a Bulbous Bow on the front to reduce the drag.)

The 8 inch guns started off as just 1 inch armor for the Mogami and Mikuma due to their hull being slightly weaker overall than their sisters Suzuya and Kumano, part of that is the fact the later two had the Bulges made directly into the hull with the substructure properly supporting it instead of being "Jerry" rigged on like the Mogami and Mikuma. This benefited them in giving a stronger overall hull and a lower center of gravity.

Lacroix does give some good info on the ship including that upgrade which is in his book "Japanese Cruisers of the Pacific War". The big issue that many people have stated, is that the turrets were slightly different depending on which ship, since they used a few different concepts with design in Suzuya subclass, and to be honest those numbers for the different 8 inch turrets could actually be just for Suzuya and Kumano, which shaved weight in the machinery department along with massive reinforcements to its subdecks.

Wells also stated it is very hard to find a lot of this info since unless they go down to check the wrecks, a lot of the upgrades and info was destroyed in the fire bombings along with the destruction of info done by the war ministry, although they did find info about the designs for the Myoko's properly armored turrets and hints at it going to the Mogami classes (Which would explain why the later two ships's turrets looked different in pictures by design style. One looked like it had bolts/rivets for the armor and the other designs looked welded. It might have been the bolt designs were the uparmored turrets.

[Gigaton]

I was actually wrong when I said "every English language source I have read" earlier. Jentschura does give 5-in turrets to Aoba and 6-in to Myôkô and Takao. However his information in general tends to be rather all over the place so to say. As an aside, I also wonder how detailed models the game will be able to provide for protective schemes. In particular Takao's barbette protection is very complex. I wonder if the game can model the full complexity?

 

I must admit I'm rather confused what turrets exactly you are claiming to have had better protection than 25mm or 25.4mm, Azumazi. Do you mean that Suzuya and Kumano had better protection for the turrets than the previous cruisers?

 

Maya's turrets have different dimensions than Myôkô as well, so I doubt the 8-in turrets on Mogami and Mikuma would have been directly compatible with any uparmouring kits intended for Myôkô. While I'm suspicious of this part of the story, I don't see why it would have been too difficult to manufacture new kits specifically for Mogami (though it does sound superfluous).

 

As for uparmouring the armament on Myôkôs, this doesn't seem to me like a small change in the least and I wonder just how practicable it would be. Even just the extra 250 plus tons for uparmouring the turrets (which does not seem to include uparmouring the 25.4mm part of the barbette) is quite large increase in top weight for a ship of this size. D. K. Brown made few illustrative examples of the domino effects even seemingly small increase in weight can result in, the following quote being one.

 

'The actual weight increase from a simple change will usually be much greater than expected; a few years before, battleships carried two 9-ton steamboats. These were replaced by two 18-ton pinnaces, a much more capable boat but the weight increase was not 18 tons. The bigger boats needed heavier derricks, rigging, and winches and the load increased by about 70 tons. If the power had been increased to restore the loss of speed and the bigger engines protected in the same way the displacement would have gone up by about 250-300 tons'.

[Azumazi]

Ahh yes, as for the armor and armament changes, I should have clarified that as an either or, as you're right the change in both would have been too high, the reason I mentioned the 8 inch guns change was for logistics purposes for the fleet.

 

The Suzuya part, was that the ship was capable of holding the weight better over the pure Mogami class due to the modifications done to her hull to counter the issues they found in the trials on Mogami. They did make shift adjustments for her and her sister, but Suzuya and Kumano had overall better designs on the bulkheads with reinforcement of DS and CNC at critical joins along with rivets to reinforce the welds. The kits were more or less add-on plates of VH (Vickers Hardened) and its rumored they were some of the plates that originally were being made for the B65 project and were just repurposed, but I find that unlikely since its actually more probably they had already made the plates for the Myoko during building and found out during trials her hull couldn't take it, especially since they needed larger motors for the turrets traverse which would have added an additional 15 tons or so.

 

As I said before though, a lot of what was done or could have been done has been lost in time, and without doing an actual dive on the wreck we wouldn't truly know.

 

I doubt they were put on the Suzuya or Kumano, but it's "possible" they put them on Mogami as someone mentioned to me during the 1944 refit into the CV.

 

Suzuya and Kumano if I remember right hadn't even been modified beyond 1939 when they were both taken through their third moderization, but those two ships would have probably been the only ones capable of holding the weight.

 

Also to recap what I said in the Ibuki thread

 

In 1937, the Myoko was originally designed to have a much heavier turret with armor of 5.9 inches forward, 50mm sides and rear, and 100mm top, however the Myoko was already top heavy and the turrets when used would have caused the same issue the Mogami had with her turrets warping the hull on firing. The Ibuki with its reinforced bulkheads and redesigned internal hull was supposedly capable of holding these heavier turrets without fear of warping the deck/hull on use or issues with training the guns. During occupation of Japan, there were plans found of the turrets to be upgraded on the E types, and some work had been done, problem was there was no evidence found if they had been used or upgraded on the ships, some Japanese say the only ship to be tried with them was the Mogami herself on her 1944 third refit since the Ibuki was converted into a CV, and the loss of the 2 rear turrets afforded her the weight stress on the hull.