VLS cells are the ship's combat magazine

Vertical launch systems offer a faster rate of fire than older swing-arm launchers, but their cell count also limits sustained fighting. Reloading VLS from an auxiliary requires a gantry, stable seas, time, and two ships placed in a vulnerable evolution. Older launchers such as Sea Dart on a Type 42 were awkward to replenish at sea, but doing so was viable. In the 48-cell example, the ship sails with 48 missiles and little practical opportunity to replace them at sea. Separate deck launchers such as Harpoon can add weapons, but the air-defence magazine in this example depends on the VLS. Cell count therefore matters to endurance as well as firing capacity.