Anti-torpedo bulge

It involved fitting (or retrofitting) partially water-filled compartmentalized sponsons on either side of a ship's hull, intended to detonate torpedoes, absorb their explosions, and contain flooding to damaged areas within the bulges.

In theory, a torpedo strike will rupture and flood the bulge's outer air-filled component while the inner water-filled part dissipates the shock and absorbs explosive fragments, leaving the ship's main hull structurally intact.

The bulge was developed by the British Director of Naval Construction, Eustace Tennyson-D'Eyncourt, who had four old Edgar-class protected cruisers so fitted in 1914.

Half an hour later, a larger, more powerful 530-millimetre (21 in) torpedo was able to sink Glatton by striking the hole caused by the initial, ineffective hit.

Later designs of bulges incorporated various combinations of air and water filled compartments and packing of wood and sealed tubes.

HMS Glatton in drydock , circa 1914–1918, showing her anti-torpedo bulge
A schematic cross-section of a ship with anti-torpedo bulges. [ nb 1 ]
USS Texas with its starboard torpedo blister removed during ongoing repair work, showing the original hull underneath.