Gunlayers Test:  2 rounds per minute
Battle Practice:  1 round per minute

1) Projectile weights from ADM 186/169.  The sources below disagree as to muzzle velocity, propellant charge weights and maximum ranges.  I have chosen to use those values given in "Jutland:  An Analysis of the Fighting."

2) Originally, 4crh projectiles were issued only to the Bellerophon and Indefatigable classes while the others used 2crh.  In 1915-16, 4crh were issued to Dreadnought and to the Invincible class.  "Greenboys" were issued starting in 1918.

3) AP Cap weights were 34.75 lbs. (15.7 kg) for the Mark VIa and 99 lbs. (44.9 kg) for the Mark VIIa.

4) In a Memorandum to the Controller dated 24 October 1910, it was stated that 12 inch (30.5 cm) APC shells striking at any angle over 20 degrees were unlikely to penetrate even 4 inches (10.2 cm) of KC armor (face hardened) and were likely to breakup at angles of 30 degrees when striking 6 inches (15.2 cm) of KC armor.  Thus, it can be seen that the poor performance of British shells at Jutland (Skagerrak) cannot have been a surprise to the Royal Navy.  Surprisingly, the memo does not suggest that the shells be improved, but instead urges that these thicknesses of armor be considered for future ship designs, as if it was to be expected that enemy shells would perform as poorly as did their own.

1) The BIX and BX mountings on Invincible were interesting in that they were electrically powered by 200 Vdc from four 200 kW steam generators and 100 kW oil motor/generators within the ship.  These mountings proved unsatisfactory and were constantly breaking down during their active service life.  As a result, they were converted to all hydraulic power prior to the start of World War I.

2) The Invincible class had staggered amidships mountings intended to allow them to shoot across the ship as well as directly forward and directly aft.  However, gunnery trials showed that the blast damage from such firings was unacceptable and the actual firing arcs were restricted to approximately the figures given above.

3) Surviving battlecruisers had 1" (2.54 cm) armor plates added to their turret roofs following Jutland (Skagerrak).

4) Battle experience showed that British turrets in general were inadequately protected, especially on these early 12" (30.5 cm) models.  Problems included the lack of gunport shields, which meant that splinters and blast could easily penetrate into the working areas.  There were also large gaps between the base of the gunhouse and the top of the barbette, leaving an area of reduced protection.  The sighting ports on top of the turrets were of an open design, which allowed both gunsmoke and sea spray to enter into the gunhouse as well as causing considerable discomfit to the crewmembers whose job it was to peer through these ports at the target.  These sighting ports and the turret rangefinders also projected up above the turret roof, which unintentionally turned them into deadly shell traps.  Finally, the sloping front roof of these turrets meant that the angle of incidence for incoming shells was less than that for a flat roof, which increased the chance of a penetrating hit.

5) These mountings were reworked during World War I to increase their maximum elevations to +16 degrees, a rather costly operation for the small increase in range thus achieved, less than 1,600 yards (1,460 m) at new gun velocities.