A flag on a boat hook protruding through a ventilator which had been left open was used to indicate that the signal had been heard.

The experiment had been performed successfully on the previous day, but the sea was much rougher on 16 October and consequently the submarine stayed inside the breakwater.

Seawater flooded through the ventilator causing the boat to develop a 40 degree inclination on the bow and dive to 90 feet (27 m) and also partially filling her with chlorine gas when it came in contact with the battery acid.

The crew managed to blow the ballast tanks to surface the boat and evacuate onto the deck, but there was an explosion whilst she was being towed back to port and she slowly sank.

The captain of the submarine at the time, Lieutenant Martin Nasmith, was later awarded the Victoria Cross for his command of HMS E11 during the Dardanelles campaign in 1915.