Which publication prescribes the requirements for ammunition afloat?

The correct publication that prescribes the requirements for ammunition afloat is NAVSEA OP 4. This document provides the necessary guidelines and procedures for the safe handling, stowage, and management of ammunition and explosives on ships. It is essential for ensuring the safety and efficiency of ordnance operations at sea and lays out the responsibilities for personnel involved in ammunition management, thereby helping to prevent accidents and ensure compliance with naval regulations.

Other publications mentioned, while related to ordnance and ammunition handling, focus on different aspects. NAVSEA OP 5 typically addresses the handling of conventional ammunition ashore. NA 01-1A-509, which encompasses multiple volumes, is a more comprehensive manual outlining various aspects of ordnance, including technical data and maintenance information, but it does not specifically focus on afloat operations like NAVSEA OP 4 does.