Depth-Specific Analysis of Efficiency and Workforce Requirements in Diving Operations under No-Decompression Conditions

This study quantitatively analyzed depth-dependent efficiency and workforce requirements for diving operations under no-decompression conditions. Based on the U.S. Navy Diving Manual, the total dive time was classified into descent, ascent, underwater workable time (WAT), and total time of dive (TTD) to assess operational efficiency between 10 and 40 m depths. Results showed that WAT decreased rapidly with increasing depth, reducing the WAT/TTD ratio from 0.99 at 10 m to 0.57 at 40 m. Consequently, deeper dives required a nonlinear increase in diver deployment, with up to 12.7 times more divers needed at 40 m than at 10 m. When repetitive diving procedures were applied, diver utilization efficiency improved by up to 28.9% at 40 m. In addition, a rational decision-making framework was proposed to determine whether the final dive of the day should be conducted, based on the criteria of remaining available time and minimum workable time. These findings provide a scientific foundation for developing depth-specific dive planning, optimizing workforce management, and establishing safe and efficient operational standards for underwater works.