(a) Each national endorsement as master or mate of vessels of less than 200 GRT is issued with a tonnage limitation based on the applicant's qualifying experience. The tonnage limitation will be issued at the 25, 50, 100, or 200 GRT level. The endorsement will be limited to the maximum GRT on which at least 25 percent of the required experience was obtained, or 150 percent of the maximum GRT on which at least 50 percent of the service was obtained, whichever is higher. Limitations are as stated above, using the next higher figure when an intermediate tonnage is calculated. If more than 75 percent of the qualifying experience is obtained on vessels of 5 GRT or less, the MMC will automatically be limited to vessels of less than 25 GRT.

(b) The tonnage limitation may be raised as follows:

(1) For an endorsement as mate, with at least 45 days of additional service on deck of a vessel in the highest tonnage increment authorized by the officer endorsement.

(2) For an endorsement as master, with at least 90 days of additional service on deck of a vessel in the highest tonnage increment authorized by the master endorsement.

(3) With additional service, which, when combined with all previously accumulated service, will qualify the applicant for a higher tonnage officer endorsement under the basic formula specified in paragraph (a) of this section.

(4) With 6 months additional service in the deck department on vessels within the highest tonnage increment on the officer's license or MMC endorsement. In this case, the tonnage limitation may be raised one increment.

(c) When the service is obtained on vessels upon which no personnel need an officer endorsement or license, the Coast Guard must be satisfied that the nature of this required service (i.e., size of vessel, route, equipment, etc.) is a reasonable equivalent to the duties performed on vessels which are required to engage individuals with officer endorsements.

(d) Service gained in the engine room on vessels of 200 GRT or less may be creditable for up to 90 days of the deck service requirements for mate.