A fast warship spends considerable machinery weight, often at the expense of armour. Speed controls engagement range only when the ship's guns can reach at least as far as the enemy's; otherwise the faster ship must enter hostile fire before it can reply. British battlecruiser guns such as the 12-inch/45, 13.5-inch/45, and 15-inch/42 were serviceable without always offering the longest range available. A personal upper limit of about 16.5 inches, or 420 millimetres, balances shell size against rate of fire, and an efficient hull form is still needed to reach high speed. In the following battle, faster British battleships close on a 26-knot French battlecruiser.
Notable Point · 1:46:30-1:50:21
Speed, range, and battlecruiser design
A design aside explains why fast ships still need gun range, armor tradeoffs, and suitable hull form before a faster battle line closes on a French battlecruiser.