By permanently covered and closed-in spaces on or above the upper deck are to be understood all those which are separated off by decks or coverings, or fixed partitions, and which, therefore, represent an increase of capacity that is or may be used for the stowage of cargo, or for the berthing and accommodation of the passengers, the officers, or the crew. No break in a deck, nor any opening or openings in a deck or the covering of a space or in the partitions or walls of a space, nor the absence of a partition shall prevent a space from being measured and comprised in gross tonnage if means are provided for closing such a break, opening or openings, so that the spaces thus closed in be thereby better fitted for the transport of goods or passengers. The upper deck is the uppermost full length deck extending from stem to stern.

§ 27.23 Vessels having a "trunk" or "turret." In the case of a vessel having a "trunk" or "turret," the deck forming the covering of the trunk or turret shall be considered the upper deck, and all spaces below that deck within the trunk or turret shall be considered as covered and closed in. The space within the turret or trunk shall be measured as are other between-deck spaces.

§ 27.24 Determination solely by §§ 27.17-27.95. Spaces considered as "permanently closed in" and spaces permitted to be exempted from measurement shall be determined solely by the provisions contained in §§ 27.17-27.95, and not by any definitions or provisions contained in the measurement rules or regulations of any country.

SPACES EXEMPTED FROM MEASUREMENT AND GROSS TONNAGE

§ 27.25 Following spaces, only, exempted. The following spaces shall be exempted from measurement and shall not be included in the gross tonnage, and no other space shall be exempted.

§ 27.26 Spaces on or above upper deck not permanently covered or closed in. Spaces on or above the upper deck not permanently covered or closed in, or which may not be readily covered or closed in. In the application of this rule it will be understood that:

(a) Certain spaces under decks or coverings but permanently exposed. Spaces under decks or coverings having no other connection with the body of the ship than the stanchions necessary

for their support are not spaces separated off, but are spaces permanently exposed to the weather and the sea and are not to be included in the gross tonnage.

(b) Certain spaces within a poop, forecastle, bridge house or other "permanently covered and closed in" superstructure or erection. A space within a poop, forecastle, bridge house, or other "permanently covered and closed-in” superstructure or erection may be considered as not permanently covered or closed in, and may consequently be excluded from tonnage, if the space is opposite an end opening which is not provided with means of closing, and which opening has a breadth equal to or greater than half the breadth of the deck at the line of the opening, and if the space opposite the opening cannot be used to shelter other merchandise than cargo or stores that do not require protection from the sea. If the opening is fitted with a coaming, the space within it is to be included in the gross tonnage if the coaming is more than 2 feet in height. This provision shall be so applied as to exempt from measurement only the space between the actual end opening and a line drawn parallel to the line or face of the opening at a distance from the opening equal to one-half the width of the deck at the line of the opening, provided that any closed-in space between the open face and the line drawn parallel to it shall be measured. The remainder of the space within a poop, forecastle, bridge house, or other superstructure or erection shall be considered as available for the accommodation of cargo or stores, of passengers or of the ship's personnel, and shall be measured and included in the gross tonnage. (See figs. 1, 2, and 3, following § 27.30.)

(1) Should the open space within a poop, forecastle, bridge house, superstructure, or erection between the end opening and a parallel line distant from the opening by half the breadth of the deck become, because of any arrangement, except by convergence of fore and aft bulkheads, of less width than half the breadth of the deck, then only the space between the line of the end opening and a parallel line drawn through the point where the athwartship width of the open space within the poop, forecastle, bridge house, superstructure, or erection becomes equal to, or less than, half the breadth of the deck shall be exempted from measurement. (See figs.

4, 5, 6, and 7 following § 27.30.) The remainder of the space within the poop, forecastle, bridge house, superstructure, or erection is to be included in the gross tonnage.

(2) When two erections extending from side to side of the ship are separated by an interval the fore-and-aft length of which is less than the least half breadth of the deck in way of such interval, then whatever be the breadth of the permanent end openings of the erections the entire erections, less the interval separating them, shall be measured and included in the gross tonnage. (See fig. 8 following § 27.30.)

(c) Certain spaces within a poop, forecastle, bridge house or other "permanently covered and closed in" superstructure or erection. In a poop, forecastle, side-to-side bridge house, or other "permanently covered and closed-in" superstructure or side-to-side erection the space directly in way of opposite openings, the height of which is at least 3 feet, in the side wall of the ship not provided with means of closing and corresponding to each other in the opposite walls of the ship shall be exempted. (See figs. 9 and 10 following § 27.30.) Passages running fore-and-aft abreast the engine-room casing and open at both ends shall not be exempted. The deck erection including same shall be considered a side-to-side erection provided its outboard sides are flush with the hull of the vessel.

§ 27.27 Certain spaces in way of opposite side openings and not provided with means of closing. Spaces in way of opposite side openings at least 3 feet in height not provided with means of closing shall be exempted. In the case of a continuous deck with one or more deck openings (usually designated as tonnage openings) that may be so closed as to permit cargo or stores to be carried in the space under the deck, or under portions thereof, only the spaces under such a deck that are exactly in way of opposite openings at least 3 feet in height in the side walls of the ship not provided with means of closing and corresponding to each other in the opposite walls of the ship shall be exempted; and the remaining spaces under such a deck shall be measured and included in gross tonnage. In case the openings in the side walls of the ship are provided with means of closing no portion of the space under

§ 27.28 Certain spaces framed in round funnels and spaces required for admission of light and air into engine rooms. The spaces framed in round the funnels and the spaces required for the admission of light and air into the engine rooms shall be exempted from measurement to the extent that such spaces are above the deck or covering of the first or lowest tier of side-to-side erections, if any, on the upper deck as defined in §§ 27.22-27.24. A deck with one or more deck openings (usually designated as tonnage openings) that may be so closed as to permit cargo or stores to be carried in the space under the deck or portions thereof would be considered as the upper deck. There shall, however, be measured and included within gross tonnage the spaces situated within closed-in side-toside erections on the upper deck, spaces framed in round the funnels and those required for the admission of light and air to the extent that such light and air and funnel spaces are below the deck or covering of the first or lowest tier of such side-to-side erections on the upper deck. There shall be exempted from the measurement of any superstructure or erection situated above the first or lowest tier of side-to-side erections on the upper deck such portion or portions thereof as are occupied by the spaces framed in round the funnels or by the spaces required for the admission of light and air into the engine rooms. Such exempted spaces must not be used for any other than their designated purpose and must be reasonable in extent.

§ 27.29 Certain spaces between inner and outer plating of double bottom. Space or spaces between the inner and outer plating of the double bottom of a vessel shall be exempted from measurement, except when used, designated or intended for carrying cargo; but the tonnage of such spaces within the double bottom as are or may be used for carrying cargo, shall be determined and included in the gross tonnage. The tonnage of double bottom tanks available for cargo may be obtained by multiplying the liquid-capacity weight by the proper conversion factor to get tons of 100 cubic feet.

§ 27.30 Portion of aggregate tonnage of hatchways. The cubical contents of hatchways shall be obtained by multiplying the length and breadth together and