Which insignia represents a sailor in charge of a small craft within the Navy?

The insignia that represents a sailor in charge of a small craft within the Navy is known as the coxswain insignia. This insignia signifies the sailor's responsibility and authority over small boats, typically those used for transport, rescue, and various operational missions. Coxswains are crucial for the safe navigation and operation of these vessels, which can include small utility crafts, rigid-hull inflatable boats, and other similar types.

While each of the other insignias represents different roles within the Navy, they do not specifically denote command over small crafts. The master-at-arms insignia pertains to a sailor assigned to law enforcement duties and security roles. The quartermaster insignia is associated with personnel who navigate and operate the ship and its equipment, but not specifically small craft. Similarly, the small craft insignia is not an official designator within the Navy for a position that commands small crafts. Thus, the correct identification of a sailor in charge of a small craft is the coxswain insignia.