How quickly could an ordinary submarine deck gun open fire?

How long did a submarine with a conventional deck gun need to open fire after surfacing?

Usually seconds and under a minute, far less than Surcouf's roughly three-and-a-half-minute preparation time.

A viewer asks for a direct comparison with an ordinary submarine deck gun. A conventional weapon could be ready within seconds and certainly in less than a minute after surfacing. Gun crews could reach the deck, open the ready-use ammunition locker, and prepare the mounting without the elaborate waterproof turret sequence. The contrast explains why a smaller exposed gun could be more useful for commerce raiding than Surcouf's much heavier battery.