Maneuvering tests and survivability

Maneuvering trials give the hull, steering gear, and machinery a different workout from constant-speed endurance tests. World War I submarine experience made zigzagging a major practice in World War II, intended to disrupt an attacker's ranging and firing position. Crash stops and rapid speed changes impose their own loads. High speed also provides strategic dash capability and makes a ship a more difficult target as it enters battle. Against aircraft, torpedoes, or missiles, erratic movement can improve the chance that a decoy succeeds even when it cannot guarantee survival. These trials also expose internal failures: one British carrier revealed a problem in a system intended to drain aviation fuel lines back to protected tanks.