In some pre-space-flight Earth navies the term leading rating, leading rate, or leading hand was used for a junior non-commissioned officer lower in rank than a petty officer and higher than a crewman. The word "leading" would be combined with their occupation to make their title, so a person might be a "leading seaman", "leading operator", or "leading mechanic".
The corresponding term in the United States Navy was petty officer third class. The corresponding military rank was corporal.
Enlisted Engineers on the USS Mumbai were referred to as mechanics and their team leaders as leading mechanics as late as 2265. (TOSS)