The Ship Model Forum

Thanks, Steve. I found the old thread. The model is impressive in its research as well as detail.

Bernd seem to have access to builder’s plans for the Bismarck for making that 1/100 models. He includes some details that I can’t find explicitly shown or mentioned in any references I can find, but which is supported by subtle features shown builder’s plans that are reproduced as secondary illustrations in some references.

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Assessing the impact of new area rug under modeling table.

I expect the location of the sea chest was due to the necessity for navigating the shallow Kiel Canal, US practice was generally to locate these on the bottom of the hull, the four piper destroyers being an exception. I would expect the Bismarck arrangement considerable complicated the design of the underwater protective system. Every warship is a study in compromises!

most of bismarck’s sea chests are on the bottom, until i counted them on the ATOS illustration i never knew she needed that many.

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Assessing the impact of new area rug under modeling table.

As I understand it, archival research in the last 20 years showed that Bismarck had active sonar installed prior to her last mission. However I’ve not seen a photo of the actual installation. The AOTS interpretation of a re-profiled bulbous forefoot to accommodate the transducers does not seem convincing to me in the absence of photos. Scharnhorst also received the transducers, but the transducers were mounted directly to the existing skin of the bulb. The size and shape of the bulb seem similar between Scharnhorst and Bismarck. Why would the Bismarck’s bulb need to be reprofiled to a new shape that seems less hydrodynamic than the original to,accommodate the transducers?

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Assessing the impact of new area rug under modeling table.

Some drawings:

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Pascal

•Battleship Bretagne 3D: https://vu.fr/FvCY
•SS Delphine 3D: https://vu.fr/NeuO
•SS Nomadic 3D: https://vu.fr/tAyL
•USS Nokomis 3D: https://vu.fr/kntC
•USS Pamanset 3D: https://vu.fr/jXGQ

Regarding Bismarck’s rudder. I think literally every other country that build warships around the period of WWII designed the rudders so it extended the full depth of the ship’s draft, all the way down to the keel line. But the Germans didn’t. The rudders on their major WWII ships are all truncated well above the keel line.

Why is this?

From hydrodynamic point of view, not only does that make the rudder smaller, but also less efficient because tip effects reduce the efficacy of the part of the rudder near the bottom.

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Assessing the impact of new area rug under modeling table.

by my count, there are 102 underwater openings on the hull of the bismarck, 77 of them are located under the bottom.

64 of them rectangular openings covered by grills, the rest appears to be smaller round pipes that open directly to the sea.

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Assessing the impact of new area rug under modeling table.

On bottom: Many can be simple bottom drain plugs for ballast capacity, water, oil, diesel and heavy fuel oil.

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Pascal

•Battleship Bretagne 3D: https://vu.fr/FvCY
•SS Delphine 3D: https://vu.fr/NeuO
•SS Nomadic 3D: https://vu.fr/tAyL
•USS Nokomis 3D: https://vu.fr/kntC
•USS Pamanset 3D: https://vu.fr/jXGQ

As they preferred to have double rudders (since the earliest dreadnoughts in WW1) they must have figured the size of each of the rudders could be much smaller an avoid the extra weight and drag. They could have opted to make these very narrow and tall (to the keel line) but then the amount of rudder input would have been very large, hence a lot of turbulence and extra drag when invoking rudder. Even the chance of rudder vibration would have increased then.

So the simple reasoning of the having twin rudders as opposed to the customary single rudder of for example the RN, would lead to smaller rudders, not making use of the full depth available.

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"I've heard there's a wicked war a-blazing, and the taste of war I know so very well
Even now I see the foreign flag a-raising, their guns on fire as we sail into hell"
Roger Whittaker +9/13/2023

Post War numerous Fletchers had the rudder extended downward, below the keel line to improve their combat radius, which at some 800 yards was just about the same as Alaska and an Iowa class Battleship. It may be that DKM went for shorter rudders due to the shallowness of the Kiel Canal. Even with the twin Rudders the Iowa's were capable on operation of maintaining 35 knots for some time. Bismarck's rudders were linked mechanically and in the final even weren't able to be disconnected. Any body know if the Iowa's had totally independent rudder activation? Certainly the Iowa design was complete before the Bismarck episode.

AFAIK iowa’s rudders are not connected. both rudders are driven independently to the same rudder angle for normal turn. the rudders can also be driven in opposite directions so they both toe in to act as water brakes during crash stop.

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Assessing the impact of new area rug under modeling table.

On Bismarck’s wreck, the starboard armored door for the conning tower is open, while the port side door has been blown away from its hinges and disappeared. When the British performed ballistic tests against the Baden, Bismarck’s design predecessor, after WWI, they also observed that a shock from a hit elsewhere on the conning tower broke the door hinge and unseated the door, and thus the conning tower door hinge design was unsound.

My question is, sound or not, the conning tower door seems to be attached by simple hinges on the Bismarck. There is no evidence of any mechanism to assist in opening or closing the door, which was 15 inches thick and must weigh several tons. Is the crew expected to use muscle power to hold the door against the rolling motion of the ship or against any list the ship developed while operating the door?

On the Iowa, the conning down door hinge is actually attached to a beefy shaft that runs below deck, which implies there is some sort of geared or powered assist for operating the door.

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Assessing the impact of new area rug under modeling table.

Greetings All,

I’m working on the Takom 1/72 Bismarck Turm “Bruno” model (which is much nicer than their Hood equivalent), and have a detailing question. Hopefully someone out there may have some info regarding the vents which surrounded the barbette, specifically, the insides of the vent flaps/covers that were opened to allow fresh air below decks.

In the famous onboard photos from 1940 (I think) there are circular markings/spots on just about all of the covers. Does anyone have any idea as to what these were and what colour they are believed to have been?

Here’s a pic with the features indicated by arrows:


Many thanks,

Frank

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Frank Allen
H.M.S. Hood Association
http://www.hmshood.org.uk

Are they not just holes, judging by the flap on the one above the centre? You can see the sunlit surface through it. That said, that dark spot under the bright might be a circular flap.

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De quoi s'agit-il?

I hadn’t noticed that before! Many thanks!

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Frank Allen
H.M.S. Hood Association
http://www.hmshood.org.uk

There is definitely a power assist for opening the conning tower doors on the Iowa. It is on the O3 level for NJ, MO, and WI. The doors also can be opened with a hand crank. It takes a fair amount of cranking to manually drive the motor but it does not take a lot of torque to move the crank. The resistance in the system is such that the door would not fly around. The hinges do not hold the doors in place when they are closed. Three thick, steel bolts extend on one side and the doors have an extension on the hinge side that fits into a recess in the conning tower.

It sounds like that simple protection was not implemented on Baden and possibly Bismarck.

To illustrate Big Jim's description of the IOWA class armored doors, here is a photo of one of IOWA's 17" thick armored citadel doors in 1981 prior to her refit -


When I did have watches on the bridge, I sometimes ventured into the conning tower (within the barbette) and made a mental note as to whether the doors were open...I certainly had no desire to get "locked" inside!!!

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HMS III
Mocksville, NC
BB62 vet 68-69

Builder's yard:
USS STODDARD (DD-566) 66-68 1:144, Various Lg Scale FC Directors
Finished:
USS NEW JERSEY (BB-62) 67-69 1:200
USN Sloop/Ship PEACOCK (1813) 1:48
ROYAL CAROLINE (1748) 1:47
AVS (1768) 1:48

They are red dots

1 The black dot on the fan cover that appears here is a "red ball" and means that the lids marked in this way (also for bulleys) must be closed at "clear ship lock state" and "Schotten dicht".

Translated from Bismarck book by Josef Kaiser isbn 3938494018 page 32

The black dot refers to the b&w photo in the book.

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Darren (Admiral Hawk)
In the not so tropical climate of the Great White North.

I offer the theory that Bismarck's rudders are so short is due to the way they are mounted. On Bismarck, the rudders are mounted paddle style. The longer the rudder, the greater the stress will be on the rudder stock.

In contrast, the rudders on U.S. battleships of this era had a rudder bearing that held the rudder stock at top and bottom. Under this arrangement, any stress on the rudder stock is countered by the rudder bearing.

It appears that nearly everyone, other than the Germans, were using the same kind of rudder arrangement by this time period.

There are a number of features of the ship to expedite passage through the Kiel Canal, Part of the wide beam was to reduce the draft on the tonnage, Sea chests moved from the bottom to the turn of the bilge and possibly the rudders shorter to maintain authority in the shallows. Other nations also had Capital ship size limitations due to harbor, dockyard and dry dock dimensions.

USN's floating dry-docks were a tremendous ace in the hole.