ing 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 § 135.86.) 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 inIcluded in the gross tonnage. (See fig. 8 following § 135.86.)

(c) Certain space 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 § 135.86.) 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.

§ 135.83 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 such a deck shall be exempted. (See fig. 11 following § 135.86.)

§ 135.84

Certain spaces framed in around funnels and spaces required for admission of light and air into engine rooms.

The spaces framed in around 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 §§ 135.61-135.63. 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-to-side erections on the upper deck, spaces framed in around 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 around 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. § 135.85 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 inIcluded in the gross tonnage. The ton

FIGURE 3.-Forecastle. a a'

nage 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.

§ 135.86 Portion of aggregate tonnage of hatchways.

The cubical contents of hatchways shall be obtained by multiplying the length and breadth together and the product by the mean depth taken from the top of beam to the underside of the hatch cover. From the aggregate tonage of the hatchways there shall be deducted one-half of 1 percent of the vessel's gross tonnage, exclusive of hatchways, and only the remainder shall be added to the gross tonnage of the ship, exclusive of the tonnage of the hatchways.

FIGURE 1.-Poop.

a a

lb

Domes, skylights, and airshafts shall be exempt from measurement. When there is an opening in the floor of a superstructure immediately below a skylight, the exemption shall include the space between the skylight and the opening in the floor of the superstructure immediately under the skylight. The remainder of the superstructure shall be included in the measurement. The space, in addition to the skylight, that may be exempted by this section is that indicated by A, B, C, D in Figure 12, which follows.

FIGURE 12.-Open spaces between skylight and

opening. Skylights

Rooms receiving light from Skylights SPACES AVAILABLE FOR PASSENGERS NOT TO BE EXEMPTED

§ 135.111 Spaces for use of passengers not exempted.

Spaces for the use or possible use of passengers shall not be exempted from measurement except as stated in § 135.82

(a).

§ 135.112 "Passengers" defined in case of army and navy auxiliary ships. In case of army and navy transports, colliers, supply ships, and hospital ships, as defined in §§ 135.1-135.3, the terms "passengers" shall include all officers, enlisted men, and other persons who are not assigned to duty and who are not duly inscribed on the ship's rolls.

SYSTEM FOR MEASUREMENT OF CUBICAL CONTENTS OF SPACES INCLUDED IN GROSS TONNAGE

§ 135.141 Use of Moorsom system as applied in any country in measuring vessels for national registry.

The cubical contents of the spaces included, by this part, in gross tonnage may, in any country where the Moorsom system of measurement has been adopted, be ascertained under that system as applied in measuring vessels for

national registry, provided that system is substantially similar to Moorsom system of measurement as set forth in §§ 135.142-135.241.

§ 135.142 Use of Moorsom system as set forth in this part.

In countries that have not adopted the Moorsom system of measuring spaces within vessels, the cubical contents of any of the spaces included in gross tonnage shall be ascertained according to the Moorsom system as set forth in the following sections: §§ 135.171-135.182 for the measurement of empty vessels; §§ 135.211-135.213 for laden vessels; § 135.241 for open vessels.

RULES FOR MEASUREMENT OF GROSS
TONNAGE OF EMPTY VESSELS

§ 135.171 Length taken on tonnage deck.

The length for the admeasurement of ships having one or more decks is taken on the tonnage deck, which is:

(a) The upper deck for vessels having one or two decks.

(b) The second deck from below for vessels having more than two decks. § 135.172 Measurement of length, in general.

Measure the length of ship in a straight line along the upper side of the tonnage deck from the inside of the inner plank (average thickness) at the side of the stem to the inside of the midship stern timber or plank there, as the case may be (average thickness) deducting from this length what is due to the rake of the bow in the thickness of the deck and what is due to the rake of the stern timber in the thickness of the deck, and also what is due to the rake of the stern timber in one-third of the round of the beam; divide the length so taken into the number of equal parts required by the following table, according to the class in such table to which the ship belongs:

(a) Class 1. Ships of which the tonnage deck is, according to the above measurement, 50 feet long or under, into four equal parts.

(b) Class 2. Ships of which the tonnage deck is, according to the above measurement, above 50 feet long and not exceeding 120 feet, into six equal parts.

(c) Class 3. Ships of which the tonnage deck is according to the above measurement, above 120 feet long and

not exceeding 180 feet, into eight equal parts.

(d) Class 4. Ships of which the tonnage deck is, according to the above measurement, above 180 feet long and not exceeding 225 feet, into 10 equal parts.

(e) Class 5. Ships of which the tonnage deck is, according to the above measurement, above 225 feet long, into 12 equal parts.

§ 135.173

Measurement of length in case of break in double bottom.

In the case of a break or breaks in a double bottom, the length of the vessel is to be taken in parts according to the number of breaks, and each part divided into a number of equal parts according to the class in the above table to which such length belongs.

§ 135.174 Finding of transverse area of ship at each point of division of length.

Then the hold being first sufficiently cleared to admit of the required depths and breadths being properly taken, find the transverse area of the ship at each point of division of the length or each point of division of the parts of the length, as the case may require as follows: Measure the depth at each point of division, from a point at a distance of one-third of the round of the beam below the tonnage deck, or, in the case of a break, below a line stretched in continuation thereof, to the uper side of the floor timber (upper side of the inner plating of the double bottom) at the inside of the limber strake, after deducting the average tickness of the ceiling which is between the bilge planks and the limber strake.

§ 135.175 Finding of transverse area of ship at each point of division of length; manner of taking depths in certain cases.

In the case of a vessel contructed with longitudinal framing, the depths are to be taken to the upper edge or inner surface of the longitudinal frames, where no double bottoms exist. In the case of a ship constructed with a double bottom, the depth shall be taken to the upper side of the inner plating of the double bottom, and that upper side shall, for the purposes of measurement, be deemed to represent the floor timber of the vessel. This rule for measuring the depth of the hold applies to double-bottom ships hav

ing top of double bottom not horizontal. Subject to the provisions of § 135.85 regarding the exemption of double-bottom spaces, if any tank or compartment between the inner and outer plating of the double bottom is used or fitted for the carrying of cargo, the tonnage of the whole of such tank or compartment shall be determined and included in the gross tonnage of the vessel.

§ 135.176 Finding of transverse area of ship at each point of division of length.

If the depth at the midship division of the length does not exceed 16 feet, divide each depth into five equal parts; then measure the inside horizontal breadth at each of the four points of division, and also at the upper point of the depth, extending each measurment to the average thickness in that part of the ceiling which is between the points of measurement. Number these breadths from above (i.e., numbering the upper breadth 1, and so on down to the fifth breadth); multiply the second and fourth by 4, and the third by 2; add these products together, and to the sum add the first breadth and the fifth. Multiply the quantity thus obtained by one-third of the common interval between the breadths, and the product shall be deemed the transverse area of the upper part of the section; then find the area between the fifth and lower point of the depth by dividing the depth between such points into four equal parts, and measure the horizontal breadths at the three points of division and also at the upper and lower points, and proceed as before, and the sum of two parts shall be deemed to be the transverse area; but if the midship depth exceed 16 feet, divide each depth into seven equal parts instead of five, and measure, as before directed, the horizontal breadths at the six points of division, and also at the upper point of the depth; number them from above, as before; multply the second, fourth, and sixth by 4, and the third and fifth by 2; add these products together, and to the sum add the first breadth and the seventh. Multiply the quantity thus obtained by one-third of the common interval between the breadths, and the product shall be deemed to be the transverse area of the upper part of the section; then find the lower part of the area as before directed, and add the two parts together, and the sum shall be deemed to be the transverse area.