When warships came too close for their main guns

How often could one ship get too close for another's guns to depress or for shells to explode inside the target?

Only rarely, but Jutland, Glowworm, and close anti-submarine encounters produced examples and improvised countermeasures.

Warships were normally designed with guns covering the engagement ranges they expected to meet, so true dead-zone incidents were unusual. HMS Spitfire at Jutland is one example, while Glowworm's final approach also pressed toward a range where ordinary gunnery became awkward. Similar problems arose when surface ships closed submarines too tightly for their mounted weapons. Merchant crews improvised answers, including a heavy object nicknamed the old piano that could be swung out on a derrick and dropped onto a submarine.