Uncrewed survey craft cannot solve a numbers shortage alone

One plausible future design is a mothership carrying several uncrewed survey launches, each with its own sonar, while retaining a crewed center for interpretation and complex decisions. Hydrography still contains enough uncertainty and practical art that close human involvement remains useful. The readiness arithmetic is simple: one hull provides only intermittent capability, two usually provide one, and three make continuous availability more credible. Four hulls can add a reserve while one remains at sea, and fleets of five or six make multiple deployed ships increasingly practical while others refit. By that measure, three survey ships constitute a minimum force rather than comfortable depth.