IOWA CLASS torpedo protection scheme Questions?......

[Dreadnought]

Edit:copy

[Dreadnought]

Gentlemen,
Excellent diagram, Note which hulls the torpedo protection is based upon the "empty" outter tank method and the "liquid" loaded method. Note that NC carries her protection tanks empty on the outside and then you have the liquid loaded tanks by either fuel oil or ballast water up against her main armor belt. Note that Iowa carries her protection outboard "liquid" loaded tanks and then the "empty" tanks up against her main armor. As far as I remember in physics (going back a bit here mind you) nothing transfers shock better then liquid transfers it. I guess we would need to ask ourselves wether the "shock" effect would be better suited to disperse the energy on the outter hull (such as in Iowas case before the main armor) as opposed to the inner hull main armor as in NC's case. IMO, another factor such as draft at the time and sea condition as well to determine just where on the hull the armor is struck and what class of armor it is.

Certainly one thing can be agreed upon they knew how to build them and they knew damage control religiously as in a few examples:

Noth Carolinias torpedo hit
Storm damage that sheered of the cruiser Pittsburghs bow.
Washingtons bow after collision

Just a few examples. Also of note up there is which countries ship hull believed in which kind of protection either live loaded or empty.

*Nice diagram.

[petsan]

Certainly one thing can be agreed upon they knew how to build them and they knew damage control religiously as in a few examples:

Noth Carolinias torpedo hit
Storm damage that sheered of the cruiser Pittsburghs bow.
Washingtons bow after collision

Just a few examples. Also of note up there is which countries ship hull believed in which kind of protection either live loaded or empty.

Amen my brother, no truer words were ever said.......)

[petsan]

I would like to see the comparrison between the two TPS on North Carolina and an Iowa. One must also keep in mind that a torpedo protection scheme is also only as good as her machinery layout. I.E. What the protection scheme is trying to protect.

Here is the machinery layout of Iowa and Montana, working on getting NKs layout

[Tiornu]

The issue has been obscured by minor flaws in the telling. Friedman's account, as I recall, places the caisson tests in 1939. That is true in part but mistaken enough to confuse the timeline. Caissons 74 and 75 tested the new TDS, and these tests showed significant problems...in 1938. Design changes followed, and Caisson H was tested in 1939. This is where the SoDak TDS came from. Iowa was similar but with additional support from transverse bulkheads due to her better machinery arrangement. My impression is this: structurally the NC system bettered SoDak's, but the liquid loading in SoDak was considered better (by BuShips, anyway). The two systems are not as different as sometimes protrayed. NC also had lower belt armor in the system, but it was not contiguous with the main belt (thus more like Montana's), and it covered only the magazine spaces (which is why you don't see it on midships sections). It seems the designers were counting on the greater bulk of SoDak's lower belt to compensate for the lesser depth of the system (both schemes were intended to defeat 700-lb TNT charges), but that was probably optimistic of them. It remains for someone to pin down exactly what was going on here, and what the final results were.
The torpedo that hit NC had a charge equal to 955 lbs of TNT. What's surprising is how well the torpedo defenses work. I don't believe any WWII battleship incurred less flooding from a 21in torpedo blast. Crewmen reported seeing flash, whether this was from burning gas or compression of the eyeball. There was certainly smoke detected after the hit. There was no confirmation that any powder was scorched.

[Dreadnought]

Do to certain changes which I cannot/will not mention I can start posting some pics here that I have not been able to post before. All I have to do now is to reduce the size of the images and post. Will start next week with a few. Stay tuned

[petsan]

Tiorno, thanks excellent post, thats the kind of data Im looking for.......


Dreadnought Waiting Anxiously.....

Do to certain changes which I cannot/will not mention I can start posting some pics here that I have not been able to post before. All I have to do now is to reduce the size of the images and post. Will start next week with a few. Stay tuned

HAPPY NEW YEAR EVERYONE"

[RustyBattleship]

Crewmen reported seeing flash, whether this was from burning gas or compression of the eyeball. There was certainly smoke detected after the hit. There was no confirmation that any powder was scorched.

Don Wolcott was a co-worker of mine in the Battleship Configuration Manager section of the Design Division of Long Beach Naval Shipyard in the 1980's. He was a Marine aboard the NC at the time of the hit at his 40mm mount back aft. He knew some of the men stationed up in the area of the hit and their description was that after the "flash" of the explosion, they could see the powder cans start to "flash". Remember, not being restricted in the chamber of a gun but only in a "tin can" they wouldn't explode right away but could start a "domino effect". However, the torpedo left a large enough hole in the side that the water rushed in too fast for the burning cans to go into a "chain reaction" which may have blown the bow off the ship.

Now, you guys can take any theorists remarks as seriously as you want. In this case, I will only go by those made by a guy who was ACTUALLY THERE.

[Tiornu]

The ship's captain was actually there.

[petsan]

Petsan,
Secondly, why worry about updating existing Iowa torpedo protection? Most, (if not all) torpedos these days explode under the hull, not next to it, mooting the point of blisters and such.

Just an afterthought Max, I think the latest ship sunk by a torpedo in battle
and is the only ship ever to have been sunk by a nuclear-powered submarine and only the second sunk by any type of submarine since the end of World War II. was the General Belgrano, an Argentine cruiser, she was sunk during the Falklands War on May 2nd 1982.

The Royal Navy submarine fired three ancient straight-running Mk 8 mod 4 torpedoes. Specs: 450 mm dia. (18 inch) Warhead: 320 lb TNT_35 knots for 2.3 km that served the Royal Navy from 1925, all through WW2 and into the 80's

two hit the Cruiser and sank her

Just a thought....how many unfriendly navies around still probably use the older straight running ones especially since theyre relatively cheap and still, if used right, very effective...........as the brits have shown

[petsan]

"The Montana-class ships were the first American ships designed with such heavy emphasis on underwater protection. Caisson tests on the South Dakota-type system indicated the "knuckle" in the holding bulkhead in way of the inner bottom was a weak point in the design. This discontinuity was eliminated in the Montana design."

copied from U.S. Battleships: An Illustrated Design History by Norman Friedman

I have 2 questions #1 As i am very new to ship design What is a "Knuckle" ?

and #2 if one (and this is pure fantasy) ever re-engined an IOWA BB
and had those huge cavernous engine spaces inside accessable, how would one strenthen the holding bulkhead from the inside of the engine room to prevent the armor bulkhead from shearing into it and rupturing it?

remember this will NEVER happen but was wondering if it did how would one do it?

[petsan]

"The Montana-class ships were the first American ships designed with such heavy emphasis on underwater protection. Caisson tests on the South Dakota-type system indicated the "knuckle" in the holding bulkhead in way of the inner bottom was a weak point in the design. This discontinuity was eliminated in the Montana design."

copied from U.S. Battleships: An Illustrated Design History by Norman Friedman

I have 2 questions #1 As i am very new to ship design What is a "Knuckle" ?

and #2 if one (and this is pure fantasy) ever re-engined an IOWA BB
and had those huge cavernous engine spaces inside accessable, how would one strenthen the holding bulkhead from the inside of the engine room to prevent the armor bulkhead from shearing into it and rupturing it?

remember this will NEVER happen but was wondering if it did how would one do it?

Anybody know what is a knuckle?

[RustyBattleship]

Anybody know what is a knuckle?

A knuckle in metal plate (steel or aluminium) is a sharp bend in the plate less than 90 degrees.

At 90 degrees it is called a Flange. Both are formed by a slow guillotine like machine called a Brake or Flanging Brake.

Rarely is plate ever shaped with more than a 90 degree bend in it so you can call it an acute knuckle if you want. And then you can only do that crossways to the length of the plate so as not to break the grain.

Did lots of that when I was a shipfitter from 1954 to 1964.