Dual crewing for continuous at-sea deterrence

Does the Royal Navy dual-crew its ballistic-missile submarines to guarantee continuous deterrence?

Yes. The working scale given here is roughly six crews for four boats, keeping one submarine at sea while preserving crew recovery time.

Continuous at-sea deterrence is a personnel cycle as well as a hull requirement. Extra crews allow one boat to remain on patrol while others refit, prepare, or recover. The approximate six-crews-for-four-boats relationship provides resilience beyond a one-crew-per-hull model. The arrangement also gives submariners a sustainable quality of life between deployments.