Lieutenant Frederick Woods, the torpedo officer, opened the test cocks on the tubes. Unfortunately, the test cock on tube number 5 was blocked by some enamel paint so no water flowed out even though the bow cap was open. Prickers to clear the test cocks had been provided but they were not used. This combined with a confusing layout of the bow cap indicators — they were arranged in a vertical line with 5 at the bottom (2,1,4,3,6, and then 5) and the "Shut" position for tube 5 on the dial was the mirror image of tube 6 above it — led to the inner door of the tube being opened. The inrush of water caused the bow of the submarine to sink to the seabed below the surface. How the outer door (bow cap) to Tube 5 became open to the sea is unknown: Woods maintained that until at least 10 minutes before he opened the tube all the indicators were at "Shut".