Modern naval firepower compressed the chance to surrender

Does finishing a disabled warship make the end of many naval battles comparable to murder?

It depends on the action and the ship's remaining ability to fight. Wooden warships often allowed more time for boarding and surrender, while modern explosive shells could destroy a disabled ship very quickly.

Wooden warships could remain afloat and repairable after losing the ability to fight. An attacker could then board, take control of the deck, and demand surrender. Explosive shells from six-inch and larger guns could destroy a modern ship much faster, compressing the interval between defeat and sinking. Whether further fire was necessary therefore depends on the ship's remaining ability to resist and the circumstances of the action.