Submarine endurance matters during peacetime intelligence patrols

Conventional submarines face limits on range and time at sea because their fuel supply is finite. Nuclear boats usually have larger hulls and more room for provisions, although their larger crews also consume those supplies. Both types still have to return when they exhaust their torpedoes because replenishing those weapons at sea is impractical. Long endurance remains useful because much submarine work consists of peacetime intelligence collection, listening and establishing what other forces are doing. Surface ships similarly spend much of their lives on presence missions and exercises. Type 45 destroyers illustrate why procurement needs to account for those everyday duties alongside wartime performance.