Hood: Battlecruiser or Fast Battleship?

[marcelo_malara]

So Dave, what happens if we just do away with the belt? Putting the main protective deck at just the waterline will protect the top of the machinery and boilers, their sides being underwater. That will give a battleship sized protected cruiser.
With respect at the sources, I undestand that there is a series of articles by David Brown in Conway´s Warship titled Attack and Defense. Do you know anything about them?
And last, seeing that scarce information exists on all this and you know quiet a lot, wouldn´t you like to write an article with some diagrams to clarify concepts, and may be it will be put in the site? I believe will be very welcome by all.
Regards

[Dave Saxton]

The basic problem with doing away with the belts, is what would happen if the ship settles or lists from flooding? This is the opposite of what the British were doing with the KGV and Vanguard classes, or the Germans by stacking another citadal over the top of the main citadel in the Bismarck class. How would such a system deal with underwater hits? Bismarck and Prince of Wales both suffered hits below the waterline at Denmark St. These battleships actually had deeper belts and better coverage than many. At high speeds the wave forms created can uncover areas below the waterline in the troughs.

I've read some of Brown's works, but I don't believe I've seen that one.

I probably don't know enough, or have a broad enough base of primary documents on hand, to write a high quality article yet.

[Karl Heidenreich]

A question here: about the main deck´s armour. Those decks were made of wood, so, the armour was built inmediatly beneath it? Was the wooden deck like a "carpet" above a steel armour?

[marcelo_malara]

You refer to the upper deck I presume...

[Karl Heidenreich]

Aye, aye

[marcelo_malara]

I saw so in the Belfast.

[Dave Saxton]

Laying teak planks over the steel weather decks performs both a cosmetic and a saftey function. One may actually be able walk on a wet deck without falling down.

The weather deck is sometimes constructed of armour grade material so it can perform ballistic functions such as decapping, fuzing, and yaw inducement, in additional to structural and corpral functions. Were post penetration induced yaw is present, then it adds to the total effective deck armour thickness. Otherwise, the rule of thumb is to take 50% of it's thickness when estimating total effective armour thickness. The main armoured deck can't be placed at weather deck level due to it's enormous weight. It would imperil the stability of the ship. The main armoured deck must be placed lower. In the case of ships like KGV it's placed one deck level down. On German warships the panzer deck is always positioned one meter above the waterline. The upper deck (weather deck in USN speak) usually performs an important structural strength role in the overall design. It's sometimes called the strength deck in Royal Navy speak. It's interesting to see how different designs juggled the various roles a deck may perform.

The easiest way, from a construction stand point, of building a armoured deck, is to construct a structural deck using structural steel, and then to lay over the structure the thicker protective plating. This was the way done on many battleships, including Yamato. This is rather inefficient in terms of weight consumed, because the structural steel essentially weighs the same as armour grade steel, but doesn't offer the same ballistic resistance.

The Americans retained the ease of laminated construction, but increased the total thickness of ballistic material, by using Special Treatment Steel for the structural componant. For example, North Carolina's main armoured deck was constructed of 35mm STS, over which 88mm STS plates were layed. However, such laminated decks don't give the sum total of effective thickness, unless the two plates are very strongly bonded.

A better way, but more difficult to execute during construction, is to use one plate of armour grade material. The material then performs both ballistic and structural functions.

[Karl Heidenreich]

Hi,

while looking for information about HMS Hood I found this:

Construction of Hood began at the John Brown & Company shipyards in Clydebank, Scotland, on 1 September 1916. Following the loss of three British battlecruisers at the Battle of Jutland, 5,000 tons of extra armour and bracing was added to Hood's design. The intention behind this change was to give her protection against 15 inch (381 mm) guns, such as her own— in theory moving her to the status of a true battleship. This led to some describing her as the first fast battleship, since the Hood appeared to have improvements over the revolutionary Queen Elizabeth battleships. To add to the confusion, Royal Navy documents of the period often describe any battleship with a speed of over about 24 knots (44 km/h) or more as a battlecruiser, regardless of the amount of protective armour. [1] [2] Classification as a battlecruiser notwithstanding, she was the largest capital ship in the British fleet at the time of her commissioning; Hood was much longer than any other British capital ship and only marginally lighter (at full load) than Britain's heaviest ever battleship, the HMS Vanguard, which was not commissioned until 1946. .

I believe this article helps a lot when trying to classify Hood. Her designation as a Battlecruiser came from a WWI precept regarding speed, even if her characteristics were those of a Battleship.

Best regards!

[RNfanDan]

I hope I'm not reiterating someone's point (I didn't see it raised, as I zipped through the replies), but Hood was a battlecruiser because that was how the ship was identified, characterized, and designed. She was financed, planned, and laid-down as a battlecruiser.

This is quite apart from the BC? / BB? debate, itself.

Speaking of that debate, are any other members radio operators or familiar with RF and radio theory? If so, I have a comment I'd like to post later, but I don't want it to be lost on an audience unfamiliar with these things.

[Bgile]

I hope I'm not reiterating someone's point (I didn't see it raised, as I zipped through the replies), but Hood was a battlecruiser because that was how the ship was identified, characterized, and designed. She was financed, planned, and laid-down as a battlecruiser.

This is quite apart from the BC? / BB? debate, itself.

Speaking of that debate, are any other members radio operators or familiar with RF and radio theory? If so, I have a comment I'd like to post later, but I don't want it to be lost on an audience unfamiliar with these things.

I have a radio / radar background, but I'm puzzled why that would be relevant to this topic. :)

[marcelo_malara]

I am a sailboat sailor and as such have a little knowledge on VHF/SSB and RADAR.

[Summoner]

I am a former radio repairer, so I may have a little knowledge when it comes to RF and the like. Not sure how much help I would be able to provide, but I can give it a go....

[RNfanDan]

The reason I posted about the RF subject, is that I am strongly reminded of something I learned decades ago, in my study of electronics, that seems to be analogous to the whole BB/BC/Fast Battleship question:

I was studying frequency-modulation (FM) methods, when I first learned the theory of phase modulation (PM). Without going into a long and pointless technical explanation, FM signals can be generated by two different means. PM is distinct from FM, but results in the same final product.

I just can't help thinking how this seemingly-unrelated example, parallels the subject of battleships(FM), battlecruisers(PM), and fast battleships (end result)! Like FM radio, fast battleships are end products, traceable to either of two distinct lines of development. Working backward from the final result, can reveal either of two possible origins.

I apologize if any of this is lost on readers, but my point is this: One doesn't necessarily need to resolve the origin of the fast battleship, if one understands and accepts that there are two different approaches to explaining its existence. I don't feel that the issue requires reconciling the two origins, beyond the end product, itself.

Perhaps a simpler analogy is this---most everyday granulated sugar can originate from beets, or from cane. Each plant is distinct from the other, is grown and processed differently, but is it really necessary to reconcile the two origins, when you stir some into your tea?