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Top Heavy Warships


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#1 Murph

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Posted 13 January 2020 - 0704 AM

I read that the US Cleveland class was very over weight, and top heavy, but compared to the Japanese Pagodas and the RN bridge structures on the modernized Warspite class they don't seem that top heavy.  What was the difference?


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#2 KV7

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Posted 13 January 2020 - 0831 AM

Wiki covers it:

'After the London Naval Treaty of 1930 passed, the US Navy took up a renewed interest in the 6" gun armed light cruiser, partially due to the fleet complaining bitterly about the 8" gun's slow rate of fire,[3] at 3 rounds per minute compared to the 10 rounds per minute achieved by 6" guns. At this time, the US Navy began to deploy drones to use as targets for anti-aircraft targets, which could simulate both dive and torpedo bombers. The results were dismaying to the fleet, as the simulations showed that without fire control directors and computers, the ships of the fleet would be almost helpless against the density of aircraft attack they envisioned the future war bringing. The mechanical computers alone could weigh up to 10 tons and had to be housed below decks for both weight and protection measures.[4] As World War II was to prove, the assumptions made pre-war were optimistic. Eventually, every anti-aircraft gun platform above 20mm would end up moving to remote power and aiming with associated fire control and radar.[5] As designed the Cleveland Class was already a tight design but requests to widen the ship were turned down because it would affect production rates.[6] In order to fit the new heavier fire control and radar systems within the allotted tonnage for a cruiser, the No. 3 gun turret was omitted. This also gave room for the enlargement of the bridge spaces to accommodate the new combat information center and the necessary radars, along with enough tonnage to fit an additional pair of 5"/38 twin mounts, which were located fore and aft of the superstructure, granting wider arcs of fire. Despite the loss of three 6-inch guns compared to the proceeding Brooklyn and St. Louis-class cruisers, the new, more advanced fire control gave the Cleveland-class ships a firepower advantage in practical use. However, the increase of light anti-aircraft artillery made the class top-heavy towards the end of World War II. To compensate for the weight increase, some ships had one catapult removed, along with the rangefinders from the No. 1 turret.[7] The top weight issues would plague the class with every addition of equipment having to be carefully weighed against what would have to be removed. Fighter control radar installation required the removal of 20mm clipping rooms for instance.'

'The six that were completed as or converted into guided missile cruisers were reactivated during the 1950s and then served into the 1970s. All, particularly the Talos-armed ships, suffered from greater stability problems than the original design due to the extra radar equipment and top weight. This problem was particularly severe in Galveston, leading to its premature decommissioning in 1970. Oklahoma City and Little Rock had to have a large amount of ballast and internal rearrangement to allow continued service into the 1970s.[10] The last of these missile ships in service, Oklahoma City, was decommissioned in December 1979.'


Edited by KV7, 13 January 2020 - 0835 AM.

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#3 shep854

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Posted 13 January 2020 - 0935 AM

Along with the guns (and ammo) came the problems of additional crew. Top-heaviness became a problemif not a real dangerwith just about every class of US warship.
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#4 Nobu

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Posted 13 January 2020 - 1349 PM

Japanese destroyer design was a constant trade-off between top heaviness and armament. The emphasis on torpedo reload capability and the tonnage limits of 1930 made that trade-off even tighter.


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#5 shep854

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Posted 13 January 2020 - 1459 PM

Then there was Chicago as CG-11
https://upload.wikim...early_1970s.jpg

Edited by shep854, 13 January 2020 - 1653 PM.

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#6 Markus Becker

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Posted 13 January 2020 - 1540 PM

Japanese destroyer design was a constant trade-off between top heaviness and armament. The emphasis on torpedo reload capability and the tonnage limits of 1930 made that trade-off even tighter.


Afaik the IJN cared about tonnage limits only in the sense that they habitually violated them. And whatever stability issues the allied ships had, that was nothing compared to the mess the IJN had made of designs.

Allied ships perfectly stable until you added radar and AA guns, lots of AA guns. Japanese ships were err 'different'.


https://en.m.wikiped...l_Japanese_Navy)
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#7 Nobu

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Posted 13 January 2020 - 1617 PM

"Habitual" insofar as the habitual peacetime hacking/snooping operations being conducted by Washington for the purpose of stealing information to leverage as needed in this particular timeframe.

 

In surface combat against IJN destroyer designs, the mess that was made of them was likely of small consolation to the allied ships hit by 24" torpedoes launched by them.


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#8 shep854

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Posted 13 January 2020 - 1657 PM

Yes, its safe to say that Long Lances caused the Allies more stability problems than they did to the Japanese.
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#9 Markus Becker

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Posted 13 January 2020 - 1734 PM

Someone asked for the salt? ;)

http://www.navweaps....ch/tech-067.php
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#10 Nobu

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Posted 13 January 2020 - 1850 PM

I feel as if someone has passed me that particular shaker before, so to speak.

 

"The world's best surface torpedomen" seems accurate enough.

 

Example No. 23's citation of "aerial harrassment" by a USN naval aviation arm with complete air dominance over the battlespace in daylight as  being of secondary importance to "the USN DD/DE counterattack" seems less so.


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#11 Rick

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Posted 14 January 2020 - 0350 AM

Then there was Chicago as CG-11
https://upload.wikim...early_1970s.jpg

Aluminum superstructure. 


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#12 Markus Becker

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Posted 14 January 2020 - 0724 AM


Aluminum?

https://en.m.wikiped...sion_damage.jpg
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#13 shep854

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Posted 14 January 2020 - 1046 AM

Yep. In thluminum was very widely used, even in RN warships, until actual damage showed that the disadvantages could not be ignored.
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#14 Rick

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Posted 15 January 2020 - 0458 AM

Aluminum was used in the superstructure of the Forrest Sherman class also. From memory, I don't believe the effects of battle damage, especially fire, was known at the time these ships were modified( missile cruisers) or when built, the Forrest Shermans. 


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#15 MiloMorai

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Posted 15 January 2020 - 0615 AM

What kind of testing was done to asses combat damage when using aluminum?


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#16 MiloMorai

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Posted 15 January 2020 - 0618 AM

Hunt Class destroyers

​

Clearly the Hunts posed a major design challenge. They would be too short and narrow and of insufficient range for open ocean work, being restricted to the North Sea and Mediterranean Sea. This sacrifice was accepted to give any chance of meeting the requirements. The demanding specifications in an overworked Admiralty design department resulted in a major design miscalculation. When the detailed calculations were done the centre of gravity was lower than expected and the beam was increased. As the first ships were being completed it was found that the design was as much as 70 tons overweight, top heavy, leaving them dangerously deficient in stability. The first twenty ships were so far advanced in construction that it was necessary to remove the 'X' 4-inch gun mount and add 50 tons of permanent ballast. These ships became the Type I group, and had the multiple 2-pounder gun relocated from behind the funnel to the more advantageous 'X' position.

The design deficiency of the Type I was rectified by splitting the hulls lengthwise and adding a 2½ foot section, increasing the beam to 31 ft 6 in and the margin of stability sufficiently for the designed armament to be shipped. These ships became the Type II group, and also had a revised design of bridge with the compass platform extending forwards to the wheelhouse face. Under the 1939 Emergency War Programme 36 more Hunts had been ordered; three of these were completed to the original (Type I) design. Depth charge stowage could also be increased from 40 in the Type I to 110.

https://en.wikipedia...r#Modifications


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#17 Rick

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Posted 15 January 2020 - 0641 AM

What kind of testing was done to asses combat damage when using aluminum?

Found these interesting, especially the first one relating to early WW2 U.S. DD. 

 

 
start at page 768.

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#18 MiloMorai

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Posted 15 January 2020 - 1619 PM

Thanks Rick.


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#19 DB

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Posted 16 January 2020 - 0938 AM

It's not just top weight. I believe that a significant proportion of BBs as completed had their armour belts completely submerged, which was not generally the design intent.
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#20 Markus Becker

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Posted 17 January 2020 - 0225 AM

"They would be too short and narrow and of insufficient range for open ocean work, being restricted to the North Sea and Mediterranean Sea. This sacrifice was accepted to give any chance of meeting the requirements."

Nothing insufficient and no sacrifice here. The ships were supposed to have a medium range for work around the UK. High endurance escorts weren't required until the Germans gained access to the Atlantic when France fell. An entirely not foreseeable event.
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