Guns
British (and foreign) pre-1914 thinking about capital ship tactics was based on the perception that guns were cumulative weapons: it would take considerable time and considerable battering to destroy or neutralise a ship. British officers had ‘knock-down’ tables showing how many minutes of fire it would take to disable particular ships. Required time was set partly by the hitting rate, so as range increased it was assumed that knock-down time would increase considerably. Success in protracted battle was expected to depend not so much on armour penetration as on smashing effect. The British also hoped that their high explosive Lyddite would create disabling toxic effects.
Hood as completed in 1920, her compass platform not yet roofed over.
Thus the destruction of the three British battlecruisers at Jutland by a few hits (possibly one each) was a shocking surprise. Afterwards the Germans claimed that their superior shells had penetrated British armour with devastating effect. However, it seems clear in retrospect that these penetrations would not have been fatal had the British not adopted what amounted to suicidal turret practices. The British were also surprised that German commander Admiral Scheer was concerned mainly with disengaging once as he spotted the main British fleet. The British needed a different kind of shellfire which could quickly immobilise an enemy so that he could be pounded to pieces or sunk by torpedoes. That was the significance of the new generation of armour-piercing shells introduced at the end of the war.
The battlecruisers blew up at Jutland not because the Germans had magic shells, but because the British had adopted extremely dangerous magazine practices because German shellfire had been so ineffective in the previous Dogger Bank battle. Moreover, British shells did penetrate German magazines (for example in the battlecruiser Seydlitz) in both battles, causing devastating fires. The Germans never took special anti-flash precautions because their powder, always contained in metal cases, could not generate the kind of flash which detonated British bagged powder. However, had the British followed the accepted precautions at Jutland, ships would have lost individual turrets without blowing up. The evidence is that HMS Lion lost ‘Q’ turret from a hit probably much like that which blew up her near-sister HMS Queen Mary; Lion’s captain and gunnery officer refused to relax the rules in order to fire more rapidly. After the First World War, the Royal Navy reverted to its earlier view that shell damage would be cumulative. Once the magazine problems revealed at Jutland had been cured, it sought to fight at a range (about 15,000 yds) at which it expected to achieve a high hitting rate. It doubted that the long range fire practised by the US and Imperial Japanese Navies was practical in this sense.
Hood is shown after her 1931 refit, with her foretop considerably extended to provide 5.5in director towers (note the rangefinder) and, abaft them, positions for pom-pom directors (at this time only the starboard one was occupied). During the 1934 refit these directors were moved to the positions occupied by the 5.5in directors, then moved again during the 1936 refit. An octuple pom-pom, which is barely visible, was mounted on the shelter deck abaft the 5.5in gun visible there. The two wings built out from the torpedo lookout position under the foretop were used to control the searchlights on the platform below. The new level added atop the compass platform was for torpedo control, with a 9ft rangefinder (not visible in this photograph). Note the vertical screen, abaft the conning tower, intended to protect the 5.5in battery from 15in gun blast. The object atop the after searchlight structure is a high-angle director, added at this time.
Nelson is shown newly completed in 1927. The angle of the ship made both torpedo-control towers visible and both signal lights on this side of the signal deck can be seen. The objects atop the stub mast above the tower bridge are intended for an interim high-angle control system (Nelson received the full system during a May to June 1930 refit). Note that at this point the flag bridge did not yet extend over the compass platform. One of the two 9ft rangefinders on the roof of the tower bridge is visible.
British capital ship main-battery guns consisted of an inner (A) tube surrounded by reinforcing tubes and hoops, their letters indicating how far they were from the A tube. A liner inside the main A tube carried the gun’s rifling. It could be replaced relatively easily. The main-battery guns of ships described in this book up to the 16in on board the Nelsons were wire-wound. In this technique, invented by an American in 1855, the wire was wound, under great tension, around the A tube; further reinforcing tubes surrounded it. Areas over which wire had been wound were subject to uniform stress, but only in the radial (outward-pointing) direction. Opponents of wire-winding claimed that these guns had lengthwise weaknesses and tended to droop and even to whip when fired. The British claimed that wire-wound guns were inherently lighter than built-up ones (using only tubes and hoops). That seems to have been true about 1905, but not by 1914. British guns of the Second World War era were built-up of multiple tubes, the prototype being the 12in Mk XIV developed in hopes (which proved abortive) that this calibre would be adopted as the maximum under the 1930 London Naval Treaty.
Shells were propelled by nitroglycerine-based ‘smokeless’ powders introduced from the late 1880s, the British version, adopted about 1890, being cordite. These powders and particularly their improved descendants (such as the British Modified cordite [MD]) burned relatively slowly, making it possible for longer guns to reach high muzzle velocities, The muzzle velocities of heavy guns increased from about 2200ft/sec in the late nineteenth century to about 2500ft/sec in 1900 and up to as much as 2800ft/sec in about 1903. Unfortunately nitroglycerine could make powders quite unstable. They could, for example, deteriorate badly when warm. British ships destroyed by spontaneous powder explosions included the battleships Bulwark (26 November 1914) and Vanguard (9 July 1917) and the armoured cruiser Natal (30/31 December 1916). Claims that unstable powder had been responsible for the disasters at Jutland seem to have been part of a larger evasion of the reality that it was due to suicidal magazine practices.
HMS Nelson is shown in the Panama Canal in 1931. She was a radical departure from previous practice, hence the subject of enormous interest to the US Navy, whose officers and enlisted men visited her and wrote voluminous reports (which survive in the SecNav/CNO correspondence in the US National Archives). Not only did she not have an open-topped compass platform, it was not even the highest level of her bridge structure. The upper level of the tower was the flag (admiral’s) bridge, with an adjacent flag plot. The compass platform was the level below it (note the bulges for the chart tables). US visitors found the view aft from the compass platform (navigating bridge) decidedly restricted, but were told that the pivoting point of the ship was about at ‘B’ turret and that anything which came abreast the bridge could be passed clear unless the rudder was put hard over towards it (one officer said that manoeuvring was confusing because the pivoting point was well forward of the bridge). The level below the compass platform was the signal bridge, carrying four signal lights (visible behind the sailors) but not controlling halyards for flags. This level also contained cabins, including the captain’s sea cabin. In contrast with previous practice, the director atop the conning tower did not have an integrated rangefinder. The new fire-control system on board the ship employed DCTs combining the functions of director, rangefinder and control (spotting and correction of fire), the forward 16in DCT being mounted at the fore end of the bridge tower. The tower structure was adopted specifically to support the heavy DCTs rigidly enough. The other two DCTs atop that tower were for 6in control. In addition to DCTs, this open platform carried a 9ft rangefinder on each side (the starboard one is just visible). A short mast in