GRT - A measure of size, equal to 100 cubic feet of enclosed space. Gross registered tonnage, i.e. a measurement of 100 cubic feet of enclosed revenue earning space within a ship. - GRT - A measure of size, equal to 100 cubic feet of enclosed space. Gross registered tonnage, i.e. a measurement of 100 cubic feet of enclosed revenue earning space within a ship.

A measure of the internal volume, or closed in spaces, of a vessel. One gross registered ton is equal to one hundred cubic feet (28.3 cbm). Abbreviation: GRT.

A measurement of enclosed passenger space, including the space in cabins, lounges, showrooms, and dining rooms. This does not apply to open spaces such as decks and pool areas (unless, of course, they are enclosed)