HMS Hood Question
 

I've been reading up on the British fleet recently, and I've got a question that's been bugging me about HMS Hood.

Simply, why was she so freaking huge? She had the exact same armament as the contemporary Queen Elizabeth class (8x 15 inch guns) and less armor than the Queen Elizabeths. Yet she was over 200 feet longer and displaced 15,000 tons more. That strikes me as incredibly inefficient.

If you're going to make the ship that much bigger and heavier, shouldn't it have more/better guns and better armor?

The Queen Elizabeths were designed as battleships. Hood was designed as a battlecruiser. The classic battle cruiser concept sacrifices armour for speed. Although the Hood was reworked with the lessons of Jutland in mind while still under construction, they weren't enough to make up for some of her defects. The Hood, like Vanguard a generation later wasn't completed in time for the war she was designed for. During the interwar years she was re-classified as a fast battleship but that only masked the fact that she shared some of the same characteristics that sent a lot of British battlecruisers to the bottom at Jutland.

Yes, I understand the difference between a battleship and a battlecruiser, but I still don't understand the massive difference in size between the Hood and the Queen Elizabeths. After all, the battlecruisers at Jutland were essentially the same size as their contemporary battleships.

The long graceful hull, coupled with light armour and small tube boilers were designed to permit the Hood to reach speeds up to and possibly exceeding 32 knots. In short, the ship would be large, light, fast and pack a fearsome punch – the ultimate battle cruiser for her time. The later generation US Iowas also had a long graceful hull giving them a similar speed, but with more advanced machinery and protection making them fast battleships.

There are several problems involved in ship design. One of them is speed. Drag increase is more severe than in other types of vehicles due to the non-compressibility of water, and the way this forces the ship to create its own waves, which in turn build up so the ship is trying to climb a hill of its own making. One of the solutions is the fineness ratio - if two ships have the same beam (width), but one is longer than the other, the longer one will be inherently faster. The other problem is power - the ship must be longer to house the machinery necessary to provide all that energy.

Torplexed mentioned the Iowa class battleships. The previous class, the North Carolinas, were nominally rated at 35,000 tons, were 729 feet long, had a 108 foot beam, and made 27 knots on 121,000 horsepower. The Iowas were nominally 45,000 tons, 887 feet long, and had the same 108-foot beam. That extra 158 feet gave them a much better fineness ration and room for a lot of extra machinery, but even with almost double the horsepower at 212,000 shp, they only went from 27 to 32 knots maximum speed.

So the Queen Elizabeth class were 641 feet long, had a beam of 90 feet and a nominal displacement of 34,000 tons, and made 24 knots on 75,000 horsepower. Hood, at 45,000 design tons, had to be 860 feet long on a 104-foot beam to carry the machinery to make the 150,000 horsepower (double that of QE) required to push her to the desired 32 knot speed.

It's a pain in the fantail, but that's why it had to be that way.




And a pain to go through all that and not really say anything more than Torplexed did.

Don't forget that the Battlecruisers in Jutland were a mere 3-6 knots faster than most contemporary Battleships, despite having much bigger engines (Iron Duke 29,000 SHP, 21 knots vs. Lion 70,000 SHP, 27 knots)

IIRC HMS Tiger, a battlecruiser, was also the biggest ship (Or one of the biggest) to participate in the battle

Thanks for the replies. It strikes me as a bit excessive to build a ship that's so much bigger than anything else just to make it faster, but I guess the fact that Hood was a flawed design isn't exactly a revelation.

True, but as I mentioned even the Iowas were so much bigger, not to make them more powerful than the previous class, but to make them capable of keeping up with the fleet carriers. Part of their design consideration was to still be narrow enough to fit through the Panama Canal locks.

Funny how practical necessities sometimes outweigh perfect design.