Dual-Crew (Blue/Gold)

Dual-crew, the blue and gold crew system, assigns two complete crews to one ballistic-missile submarine and rotates them between patrols so the expensive boat spends the maximum fraction of its life at sea on deterrent patrol. While the blue crew is on patrol, the gold crew rests, trains, and prepares; they swap during the short turnaround alongside the tender or in port, then the rested crew takes the boat back out. The US Navy applies it to Ohio-class SSBNs and SSGNs; the practice underpins both US patrol availability and the UK’s CASD.