(a) Endorsements as master and mate of vessels of less than 1,600 GRT are issued in the following tonnage categories:

(1) Less than 1,600 GRT.

(2) Less than 500 GRT.

(3) Between 25 and 200 GRT in 50-ton increments and with appropriate mode of propulsion such as self-propelled, sail, or auxiliary sail.

(b) Experience gained in the engine department on vessels of appropriate tonnage may be creditable for up to 90 days of the service requirements for any master or mate endorsement in this category.

(c) An officer's endorsement in this category obtained with an orally assisted examination will be limited to 500 GRT. In order to raise that tonnage limit to 1,600 GRT, the written examination and service requirements must be satisfied.