Second World War
Battle of the Atlantic  - Weapons and Technology

Combatants in the battle of the Atlantic relied on weapons and technology to attack the enemy, to defend themselves, to communicate, and to rescue friends and foes.

Taffrail Log

This device, named after the taffrail (the rail around the stern of a ship) measures the distance a vessel has travelled through the water.

The log worked by trailing a spinner (also called a "fish") in the water behind the ship. The ship's motion through the water caused the spinner to rotate, driving a mechanism that calculated how far the ship had travelled and indicated the results on a dial. Other versions of taffrail logs measured a ship's speed rather than the distance travelled.

Traffrail Log
CWM 19660074-009