Gross register tonnage
Gross register tonnage means the tonnage of a vessel, less certain spaces exempt under 69.169, and is the sum of the following:
(1) Under-deck tonnage (§ 69.163).
(2) Between-deck tonnage (§ 69.165)
(3) Superstructure tonnage (§ 69.167)
(4) Excess hatchway tonnage (§ 69.115)
(5) Tonnage of framed-in propelling machinery spaces included in calculating gross register tonnage (§ 69.121(d)(1)).