tinuation of the side tank tops. (See Figure 25 (§ 2.65).) The third length immediately below the second part should equal that of the second. The breadths are taken between the inboard faces of the side tank bulkheads, and depths from athwartship lines forming continuation of the side tank tops. The fourth part will extend from a line athwart the after bulkhead of side tanks to a point aft where tonnage lengths usually terminate. Measure separately a side tank, the tonnage of which is to be doubled, assuming both tanks are identical as they usually are; then the sum of the tonnage of the several parts thus found shall be deemed the capacity under tonnage deck. § 2.37

Outside shaft tunnel.

To find the under deck tonnage of a vessel having an outside shaft tunnel, the shape of a section of which is usually the segment of a circle, measure the portion of the tunnel space included by the process of measurement in the under deck tonnage and subtract it therefrom. Figure 26 (§ 2.65).)

(See

Divide the length of such tunnel into a convenient number of equal parts, then find an area at the points of division of the length, also at the ends, if the end ones yield an area, by the following formula:

C=

chord of the segment of a circle. h-height of segment (from chord to crown of arc).

Having found the required areas, proceed in the manner provided for using the areas as ordinates in determining under deck tonnage, finding the sum of even numbered areas multiplied by 4; the odd numbered areas multiplied by 2, except the first and last which are multiplied by 1. Then multiply the sum so found by one-third common interval between sections. The result divided by 100 gives the tonnage of the tunnel to be subtracted from the under deck tonnage found by ignoring initially the projection of the crown of the tunnel into the hold. § 2.38 Square end vessels having head blocks.

(a) In the case of vessels with square ends having head blocks extending from the deck to the bottom longitudinals on the rake of the bottom, the termini of the tonnage length will be at the

inboard face of said block, and the area of the first and last section will equal the area of the inboard face of said block. (See Figure 27 (§ 2.65).)

(b) Should the head blocks extend inboard of the inboard face of the end frames (see Figures 28 and 29 (§ 2.65)), or should the head plates be excessive (see Figure 30 (§ 2.65)), consider the termini of the tonnage length to be at points inboard from the ends of the vessel, equal in distance to the thickness of the shell plating, depth of side frame, plus ceiling if fitted. Rubbing strakes to be excluded. § 2.39 Between decks.

(a) The tonnage of the space between the tonnage deck and the deck next above shall be ascertained as follows:

(1) Measure the inside length of the space at the middle of its height, from the ceiling at the side of the stem to the ceiling on the midship stern timber; or, if there is no ceiling take the length from a point forward where a continuation of the lines of inboard faces of the side frames intersect the center line of the vessel aft to the inboard face of the midship stern timber. Divide the length into the same number of equal parts into which the length of the tonnage deck is divided.

(2) Measure also at the middle of its height the inside breadth of the space at each of the points of division of the length, the breadth at the stem, and the breadth at the stern (if round, as in the case of poops of similar form). Number the breadths successively 1, 2, 3, etc., commencing at the stem.

(3) Multiply the second and all other even numbered breadths by 4 and the odd-numbered breadths by 2, except the first and last which are multiplied by 1. Multiply the sum of these products by one-third of the common interval between the points at which the breadths were taken; the result will give, in superficial feet, the horizontal area at the mean height of such space.

(4) Multiply the mean horizontal area by the average height taken between the planks of the two decks and the product will be the cubical contents of the space; which, divided by 100 shall be deemed the tonnage to be included among the items comprising the vessel's gross tonnage.

(b) The tonnage of each of the between decks above the tonnage deck shall be severally ascertained in the manner

Permanent

(a) Permanent erections. erections; i.e., forecastle, bridge, poop, break, etc., on or above the upper deck, shall be measured tier by tier, and, exclusive of closed-in exemptible spaces, and open spaces, shall be included in the gross tonnage.

(b) Length. Measure at half height the mean length of such a space along its center longitudinal line, from and to the line of the inboard faces of the frames, or stiffeners, or ceiling if fitted. Divide the length into an even number of equal parts the common intervals of which shall be most nearly equal to that of the parts into which the tonnage length was divided. (See Figure 31 (§ 2.65).)

(c) Breadths. Measure at the middle of its height the inside breadths; namely, one at each end and one at each point of division of the length, numbering them successively 1, 2, 3, etc., the number one breadth being at the extreme forward end of the length.

(d) Round-end erections. If the after end of an ordinary poop or a house is in the form of a continuous arc of a curve, its breadth at the extreme after end of its length shall be one-half of the preceding breadth. If the after end of such a poop or house is in the form of an arc of a curve which is broken at its extreme after end by a decided flat, its breadth at the extreme after end of its length shall be two-thirds of the preceding breadth. (See Figures 32 and 33 (§ 2.65).)

(e) Round-end erections. If the forward end of a house is in the form of a continuous arc of a curve, its breadth at the extreme forward end of its length shall be one-half of the succeeding breadth. If the forward end of such a house is in the form of an arc of a curve which is broken at its extreme forward end by a decided flat, its breadth at the extreme forward end of its length shall be two-thirds of the succeeding breadth.

(f) Multipliers. Multiply the even numbered breadths by 4, and the odd numbered ones by 2, except the first and last which are multiplied by 1.

(g) Horizontal area. Multiply the sum of the products by one-third of the common interval between the points at which the breadths were taken; the result will give the horizontal area at the mean height of such space.

(h) Height. Multiply the mean horizontal area by the average height measured between the decks, or the extended line of same. (See B and C in Figure 9 (§ 2.65).) Divide the product by 100 and the quotient shall be deemed the tonnage of such space.

(i) Superstructures having breaks. Superstructures having breaks in their covering deck or side lines shall be measured in parts. (See Figure 34 (§ 2.65).)

(j) Superstructures on small craft. Superstructures on small craft shall be measured similar to the method for finding the gross tonnage of larger structures. When a superstructure is erected over a cut-away portion of the tonnage deck, the height of such superstructure is to be taken from the under side of its covering deck to a line of continuation of the tonnage deck. Should there be no camber to the tonnage deck, allow for same, in the covering deck of the erection if it exceeds 0.15 foot. After subtracting the tonnage of exemptible spaces in the superstructure, the remainder shall be listed under a name describing the erection, among the items comprising the gross tonnage.

(k) Height of a turtleback. The mean height of a superstructure referred to as a "turtleback" may be found by taking a height at each point of division of its length, at the after terminal of its length, and at one-third common interval abaft the forward end of the length. The sum of the heights so taken, divided by the number of heights, will give a sufficiently accurate mean height.

The hatchways referred to are the ones out in the open or in open spaces on the upper deck to the hull and on closed-in deck erections. Hatchways on between decks and on the deck of open erections are not to be measured and included in the aggregate of hatchways from which the statutory deduction is to be made. The total hatchways on between decks and on the portion of the decks within closed-in erections on the upper deck to the hull are automatically included in the between-deck spaces and in the said erections by the process of measurement; and, of course, the hatchways on decks of open erections are not to be considered, serving as they do spaces not entering into the tonnage of the vessel.

§ 2.42 Record of exempted spaces.

The tonnage measurement of all spaces that the measurer has not included in the gross tonnage of the vessel must be recorded in detail on customs Form 1410, "Tonnage Admeasurement" which, when forwarded to the Bureau for examination and appropriate action must be accompanied by suitable plans or sketches drawn to scale, or a complete explanation for the proper consideration of the exemption of such spaces. [T.D. 66-57, 31 F.R. 4295, Mar. 11, 1966] § 2.43 Enclosed spaces exempted from inclusion in gross tonnage.

In addition to the spaces omitted from inclusion in gross tonnage under the provisions of § 2.80 on vessels measured in accordance with the provisions of §§ 2.80 through 2.100, the following closed-in spaces situated on or above the upper deck shall not be included in the gross tonnage provided they are reasonable in extent, adapted and used exclusively for the purposes outlined:

(a) Companions. Companions and booby-hatches serving as a protection for companionways (stairways or ladderways) leading to spaces below, whether such spaces are exempted or not. (See a, b, c and d in Figure 35 (§ 2.65).)

(b) Galleys. Spaces fitted with ranges or ovens (bakeries), without regard to the category of the persons they serve.

(c) Light and air. Spaces forming part of the propelling machinery space, or serving for the admission of light and air to such machinery shall be exempt under the heading of light and air. When no part of the propelling machin

ery extends below the upper deck, the space occupied by same is exemptible in its entirety together with such fuel bunkers as are located on or above the upper deck. Where fuel bunkers or tanks are located wholly or in part below the upper deck the space so occupied below the upper deck is not deductible.

(d) Light and air on small boats. (1) A house of reasonable size, into which the propelling machinery projects above the deck line, or a similar house used exclusively for light and air over such machinery on small boats is exempted, in its entirety, as light and air.

(2) A compartment of reasonable size, bulkheaded off and similarly used, located in a house serving other purposes is likewise so treated.

(3) When propelling machinery and/ or light and air space, not bulkheaded off, is in a house serving other purposes, the actual length and breadth of the engine plus 2 feet each side and each end for working space, if such space is available, projecting up into the house becomes the length and breadth of exempted light and air, exclusive of such part as may be decked over and available for other purposes.

(4) If bunks, galley, supplies, etc., are located in the hull abreast the engine and under a house open to same, as described in preceding paragraph, and the 2-foot allowance for working space on each side of the engine base overlaps working space at galley, or as the case may be, allow one-half the actual breadth on each side the engine, which breadths plus the actual engine breadth projecting up into the house becomes the permissible breadth of light and air exemption.

(e) Machinery spaces. (1) Spaces occupied by machinery other than propelling machinery.

(2) The spaces occupied by dredging machinery on the upper deck of dredging vessels which are not self propelled but which are required to be documented are to be exempted. No allowance is to be made for spaces occupied by such machinery below the upper deck.

(f) Skylights. Skylights and domes affording ventilation and light to the erection thereunder, except skylights over propelling machinery. None of the space below the covering deck of such erection shall be exempted from inclusion in tonnage unless an opening is left in the deck of the superstructure immediately under such skylight or dome to

give ventilation and light to spaces below such deck line. (See exempted skylight and a, b, c and d in Figure 36 (§ 2.65).) For the treatment of skylights over propelling machinery, see paragraph (c) of this section.

(g) Special exempted water-ballast spaces. (1) Any space other than the double-bottom space adapted only for water ballast, certified by the collector not to be available for the carriage of cargo (other than ballast water for use for underwater drilling, mining, and related purposes, including production), stores, supplies, or fuel, shall be deducted from the gross tonnage as measured to get gross register tonnage.

(2) Adaptation for water ballast consists of having the space or spaces properly constructed and tested as ballast tanks; that the pumps, pipes, etc., for filling and emptying such tanks must be of suitable dimensions, connected to the ballast system, and completely independent of the cargo, fuel oil, feed or domestic water pumping apparatus. Access shall be only through oval or circular manholes, whose greatest diameter must not exceed 2 feet in the watertight deck. Where a hatch exists over a space now to be used for the carriage of water ballast, plating shall be fitted and riveted or welded to form a watertight cover and a manhole as above described may be fitted in this cover plate. Such manholes, except when fitted on the weather deck, may be provided with a coaming not exceeding 6 inches in height. If these spaces are found being used for purposes other than water ballast, they are to be added to the gross tonnage of the vessel, and so included until such changes have been made as will definitely preclude their use for purposes other than for water ballast.

(3) No space will be deemed to be adapted only for water ballast unless the Bureau is satisfied that the primary purpose of the space is to afford a means of maintaining stability, trim, immersion, seakeeping1 capabilities, or strength conditions under varying conditions and requirements of the vessel's operation and that the space claimed for exemp

1 The term "seakeeping" as used in this paragraph is defined as the ability of a vessel to maintain good behavior at its designed speed or at a speed as close as possible to its designed speed under all conditions of sea and weather which the vessel may encounter in its designated service.

tion is necessary to and available at all times for any one of these purposes. An application for exemption of waterballast spaces in excess of 30 percent of the vessel's gross tonnage, calculated without any allowance for water ballast, shall be submitted for approval to the Commissioner of Customs, accompanied by a statement in writing from the vessel owner or his representative as to the circumstances of use or construction of the vessel which make such an allowance necessary and proper and verifying that the conditions specified in this paragraph have been and are met. Any change in the facts on the basis of which a water-ballast exemption is granted under this section shall be promptly reported to the collector of customs for his determination as to whether there has been a change in the use of spaces requiring an adjustment of tonnage under § 2.64.

(h) Water closets. Any public room or compartment, if of reasonable size, fitted with hopper or hoppers, is, for admeasurement purposes, a water closet. This definition includes a room or a compartment designated as a toilet, fitted with urinal, or urinals, shower bath or shower baths, in addition to the hopper or hoppers. A crew water closet is considered public if it serves more than one member of the crew.

(1) Wheelhouse. The space for sheltering the man or men at the wheel. If the space is a combined wheelhouse and chart room, only such space as is necessary for the proper steering of the vessel shall be exempted. Should the space be partly above and partly below the upper deck, such part above the line of continuation of said deck is exemptible. [28 FR. 14553, Dec. 31, 1963, as amended by T.D. 66-57, 31 F.R. 4295, Mar. 11, 1966] § 2.44 Passenger cabins.

(a) Except as provided in § 2.80 (b), passenger cabins and staterooms immediately on the upper deck to the hull, permanently closed-in and fitted up for permanent use of passengers, are to be included in gross tonnage. They will be exempted only when they have no berthing accommodations and have only temporary arrangements to protect passengers on short voyages from rain and the shipment of seas, constituting sheltered spaces under cover and open to the weather; that is, not enclosed.

(b) Cabins and staterooms when assigned for use of passengers only, constructed entirely above the first deck which is not a complete deck to the hull (see § 2.21), may be exempted from inclusion in tonnage. In the case of Army transports, colliers, supply ships, hospital ships, etc., the term "passengers" shall include all officers, enlisted men, and other persons who are not assigned to ship's duties and not entered on the ship's articles, and no deductions for spaces occupied by such persons shall be made; nor are cabins and staterooms occupied by them when situated on a deck not a deck to the hull to be included in gross tonnage.

(c) For admeasurement purposes a cabin is defined as an apartment of a vessel, or the portion of the apartment that is assigned for the exclusive use of passengers. A cabin may consist of staterooms, bathrooms, toilets, libraries, writing rooms, lounges, dining rooms, saloons, smoking rooms, play rooms, etc., individually or collectively. The following spaces-smoking room, lounge, foyer, library, and similar public spaces, with or without a stateroom-would, for instance, be considered cabins. In short, any passenger stateroom or public space reserved entirely for the use of passengers is to be considered as coming under the meaning of the word "cabin".

(d) A passenger stateroom is defined as an apartment, or one of the units of an apartment on a vessel, intended primarily to afford sleeping and/or other accommodations for passengers traveling alone or together.

[28 F.R. 14553, Dec. 31, 1963, as amended by T.D. 66-57, 31 F.R. 4295, Mar. 11, 1966]

§ 2.45 Open superstructures on or above the upper deck.

(a) Treatment. Nothing shall be added to the gross tonnage for any sheltered space on or above the upper deck which is under cover and open to the weather; that is, not enclosed.

(b) Determination as to inclusion in gross tonnage. In deciding whether or not superstructures are permanent closed-in spaces and should be included in tonnage, the measurer should have regard to the character and structural condition of such erections.

(c) Tonnage openings. A forecastle, bridge, poop, or any other permanent superstructure on or above the upper deck to the hull, with one or more

openings in its sides or ends, not fitted with doors or other permanently attached means (except as provided for below) of closing them, shall be exempted from inclusion in gross tonnage if the opening or openings are in conformity with the following provisions:

(1) Two 3 x 4 foot tonnage openings. When there are in one of the end bulkheads, two tonnage openings, each 3 feet wide by 4 feet high in the clear, one on each side of the center line of the end bulkhead.

(2) One 4 x 5 foot tonnage opening. When there is in one of the end bulkheads, as near as is practicable to the center line of the space, one tonnage opening at least 4 feet wide by 5 feet high in the clear, or its equivalent. equivalent opening is considered to be one of at least 20 square feet in the clear, resulting from a breadth in excess of 4 feet and a height of not less than 3 feet.

An

(d) Intermediate bulkheads. If the space is subdivided by intermediate bulkheads, such bulkheads shall have an opening or openings of the same dimensions as prescribed above.

(e) Coamings. If coamings are fitted to tonnage openings, their height must not exceed 2 feet at any part.

(f) Permissible temporary closures for exterior bulkhead tonnage openings. Tonnage openings prescribed for the above-mentioned superstructures may be temporarily closed by shifting boards dropped into channel sections at the sides of such openings, or by plates or boards held in place by hook bolts, spaced not less than 1 foot apart, fitting over the stiffener bar at the sides, top, and bottom of such openings, or by a plate or boards held in place by bolts and cross pieces so arranged as not to be held in place by cleats or other attachments to, or bolts through the bulkhead. (See Figures 37 to 43, inclusive (§ 2.65).) Cover plates, etc., must fay against the bulkheads.

(g) Battening, gaskets, etc. In no case is the use of battening, caulking, or gaskets of any material permitted.

(h) Permanent fixtures. Cleats, stud bolts, hinges attached to, or bolts in bulkheads at the edges of tonnage openings are prohibited as they are considered to be part of the means, in conjunction with the plate or boards, of closing the tonnage opening.