§ 2.47

An open structure on small craft. (a) A house on a small craft is considered open to the weather and exempted from inclusion in tonnage provided the after end of such house is entirely open, from the under side of its roof beam down to a coaming not exceeding 3 inches in height, if there be a coaming, otherwise to the deck or line of same; and open in an athwartship direction from and to the inboard face of the end side stiffeners. (See Figures 45 and 46 (§ 2.65).) Closed-in spaces within an open erection will be treated according to their usage.

(b) Such an opening may be guarded by wire mesh screens and/or temporarily closed by canvas secured at the top and lashed down or buttoned in place at the sides and bottom.

(a) In ascertaining the tonnage of open vessels the upper edge of the upper strake shall form the boundary line of measurement, and a tonnage depth shall be taken from a line athwart the upper edge of said strake, at each point of division and each end of the tonnage length.

(b) An open vessel is one of any length without a deck, or with only a partial deck or partial decks, the total length of which is less than one-half her tonnage length.

(c) Further, a vessel having a tonnage length of less than 50 feet and a partial deck of any length or a single full length deck, which, in either case, lies more than one-sixth of the midship depth below the line of the upper edge of the upper strake to the usual point in the hold for taking the register depth, shall, for admeasurement purposes, be deemed an open vessel unless it has a mechanically refrigerated hold or holds. § 2.49 Deductions from gross tonnage.

(a) General. To ascertain the net tonnage, the tonnage of the following spaces meeting certain requirements shall be deducted from the gross tonnage.

(b) Requirements. No space shall be deducted unless it has been included previously in the vessel's gross tonnage; is reasonable in extent for the purpose to which it is appropriated; and is certified by marking as prescribed in paragraph (c) of this section showing that it is used exclusively for such purpose.

(c) Marking. The following markings are required by paragraph (b) of this section: For each space appropri

ated exclusively for the use of the master, including the master's bathroom, bedroom, dressing room, observation room, office, reception room, sitting room and water closet-"Certified for the Accommodation of Master"; for each space appropriated exclusively as a bedroom for the use of crew members, including officers other than the master-"Certified to Accommodate Seamen"; and for other deductible spaces-"Certified 'inserting the appropriate designation such as-"Boatswain's Stores," "Chart House," "Dynamos,” "Galley," "Hospital," "Messroom,” “Office of Chief Engineer," "Pump Room," "Radio," "Steering Gear," "W. C." The following abbreviations may be used: "Cert. Accom. Master," "Cert. Accom. Seamen," "Cert. Boatswain's Stores," "Cert. Chart House," "Cert W. C." or “Cert. ------," inserting the space designation. The marking shall at all times be embossed, center-punched, or otherwise permanently cut in metal, and painted over with oil paint in a light color on a dark background, or a dark color on a light background, or carved or branded at least three-eighths of an inch in wood over the doorway, on the inside of the deductible space. Roman letters and Arabic numerals at least one-half of an inch in height shall be used and shall be readily legible at all times. If desired, the marking may be made on a plate of metal (but not of other material) permanently fastened in place by means of welding, riveting, or lock-type screws. The metal certification plates may be fastened in place to a metal door frame, on the inside of the space, by means of a metal-to-metal synthetic contact adhesive if the vessel owner or his agent satisfactorily establishes that the bonding agent is currently acceptable to the U.S. Coast Guard or the Department of the Navy for use on merchant ships or naval vessels for affixing metal hull label plates; and, further, certifies that the metal-to-metal bond will be accomplished in accordance with the techniques recommended by the manufacturer of the bonding agent.

(d) Crew spaces. The tonnages of the spaces or compartments exclusively occupied by and appropriated to the use of the officers and crew of the vessel including:

Bathrooms. A bathroom is a compartment or a room containing (1) a bath tub, or (2) a bath tub and a water closet, or (3) a shower

Recreation room.

Shower baths.

Sleeping rooms.

Smoking room.

Water closets, private.

A private water closet is defined as one intended to serve not more than one member of the crew, whose stateroom or bedroom affords the only means of entrance thereto and is treated as part of the room served by it. Other water closets are considered to be public water closets for admeasurement purposes.

Water closets, public-below the upper deck.

Passageways and companionways serving the above spaces.

But none of these spaces when used by the passengers on a passenger vessel are to be deducted nor is the clerk's, purser's or paymaster's office deductible.

(e) Nondeductible spaces on deductible passageway. Lockers of less than 2 tons each, containing medicine, linen, mops, etc., for the free use of the crew; the ship's office, also spare rooms, not exceeding two in number and used as required by a pilot, customs officer, reserve engineer, a company official or employee shall not invalidate the deduction of a passageway serving as sole access to their location.

(f) Master's cabin. Any space exclusively for the use of the master. This space includes sleeping room, dressing room, bathroom, office, and passageways serving the master's accommodations.

(g) Measuring deductible spaces. Deducted spaces, rectangular in shape, are to be measured by taking the product of the three dimensions, but when bounded by curved surfaces conforming to the sides of the vessel below the tonnage deck exceeding 15 feet in length, they are to be measured according to the formula on the back of Form 1410 for measuring peak tanks. When the space is less than 15 feet in length it may be measured by any practical method.

(h) Platforms. (1) When there is a platform, not more than 1 foot above the top of the bottom frames, to give a flat surface at the bottom of deductible spaces, and the space between the plat

form and said frames is not used for the stowage of gear, stores, etc., or for any other purpose, take depths of transverse sections to the top of the bottom frames and find areas as in the case of transverse sections for finding the tonnage below the tonnage deck. (See Figure 47

(§ 2.65).) P represents the platform 1 foot above the top of the bottom frames. A, B, and C are the positions of the sections. The forward section A, being sharp, yields no area.

(2) When the platform is more than a foot above the bottom frames, then find the areas only of the portion of the sections above the platform. (See Figure 48 (§ 2.65).)

(3) The depth of deducted spaces extending from the top to bottom of a deck erection may be taken between the same points as the depths used in finding the tonnage of the erection. In other words, if the erection was measured before the deck covering, if any, was laid and the ceiling or paneling, if any, overhead was fitted, and depths were taken from the underside of the covering planks or plating of the deck over as required by the law and regulations to the deck beneath, the deck covering and overhead ceiling are to be disregarded in obtaining depths of the various deducted spaces. In determining the number of men that may be berthed in a space the act of March 4, 1915, (38 Stat. 1165; 46 U. S. C. 660-1) is to govern.

(1) Spaces in the between decks, etc. Deducted spaces in the between decks or erections on or above the upper deck having curved sides are to be measured according to § 2.40.

[28 F.R. 14553, Dec. 31, 1963, as amended by T.D. 56399, 30 F.R. 6116, Apr. 30, 1965] § 2.50

Navigation spaces.

(a) Spaces used exclusively for navigation. Spaces used exclusively for maneuvering or navigating the ship shall be deducted from the gross tonnage to the extent of what is considered reasonable. When the steering gear, anchor gear, helm, etc., are situated within a room unnecessarily large for the purpose, or are not partitioned off at all, a 2-foot allowance on every side of the apparatus may be made for working space. The height to be allowed should, as a rule, be the mean height of the between deck space.

(b) Anchor gear. The spaces below, occupied by anchor gear, include the capstan, windlass, and chain locker. When the fore peak is used exclusively as the

chain locker, it is to be measured in the manner prescribed for measuring fore peak tanks when used for water ballast.

(c) Boatswain's stores. (1) Subject to the restrictions stated below, any space exclusively appropriated to and used for keeping the boatswain's stores may be deducted.

(2) The allowance for boatswain's stores shall be 1 percent of the gross tonnage in vessels of 100 gross tons and over, but this allowance shall in no case exceed 100 tons. In the case of vessels of less than 100 gross tons this deduction shall not exceed 1 ton.

(d) Chart room. (1) The space for keeping the charts, nautical instruments and for plotting the course. When the space is a combined wheel and chart room, such part as is not exempted as wheelhouse shall be deducted.

(2) In small vessels requiring the use of navigation charts, and where the cabin or saloon is the only space available for filing or use of such charts, one-half of the cabin or saloon, may be allowed for this purpose provided the allowance does not exceed 11⁄2 tons.

(e) Donkey engine and boiler. (1) The space occupied by a donkey engine and boiler, if situated within the boundary of the engine room or the casing above it, and if the donkey engine is used as an auxiliary in connection with the main machinery for propelling the vessel and this space forms part of the actual engine room it shall not be subject to a separate allowance.

(2) When the donkey engine and/or boiler is in a house above the upper deck and not used in connection with the main propelling machinery as described above, the space thus occupied is an exemption and therefore must not be included in the gross tonnage of the vessel.

(3) In all other cases the space occupied by the donkey engine and boiler, if same are connected with the main pumps (except cargo pumps) of the vessel, is to be allowed as a deduction from the gross tonnage, if reasonable in extent. It must be certified in the same manner as other deductible spaces.

(f) Dynamo spaces. The space or spaces when reasonable in extent, occupied by dynamos, switchboards and apparatus necessary for the operation of same, when located below the upper deck shall be deducted regardless of the service for which the dynamo or dynamos are used.

(g) Pump room. A pump room or space below the upper deck containing

(a) Engine room must be measured. Notwithstanding the ratable allowance for propelling power for which the act of March 2, 1895 (28 Stat. 741; 46 U.S.C. 77) provides, it is necessary to measure the engine room, regardless of size, in order to ascertain whether the allowance to be deducted for propelling power shall be regulated by a percentage of the gross tonnage or by the actual tonnage of the engine room ascertained by measurement.

(b) Spaces included in engine room must be in gross tonnage. No space shall be included in the tonnage of the engine room unless it has first been included in the vessel's gross tonnage.

(c) Deductions from engine room. Conversely the spaces occupied by cabins, storerooms, etc., and any space not used in connection with propelling the vessel but included in the tonnage of the engine room through process of measurement must be subtracted therefrom. § 2.52 Spaces included in engine room.

The space occupied by the engine room is to be understood to include not only that occupied by the engine room itself but also the space occupied by the boiler room, together with the spaces strictly required for the working of the engines and boilers, and consisting of the following items:

the point or height at which the slope terminates. (See Figures 49 and 50 (§ 2.65).)

(b) Space between crown and upper deck. Space between the crown and the upper deck framed in for the machinery or for admission of light and air thereto. (c) Space above upper deck. Space similarly framed in above the upper deck when permitted under paragraph (1), act of March 2, 1895 (28 Stat. 741; 46 U. S. C. 77).

(d) Shaft tunnels, etc. The shaft tunnel or tunnels and the thrust block recess.

(e) Escape shaft. The trunked ladderway leading from the after end of the shaft tunnel to the deck, provided that it is no larger than is necessary for the purpose of access to and escape from the shaft tunnel. The part of an escape shaft above the upper deck line, also the companion sheltering the escape shaft, is accorded the treatment of light and air space.

(f) Fuel oil transfer pump. (1) When the fuel oil transfer pump is located in a separate space, this space, if reasonable in size, may be considered propelling machinery space provided said pump is not used for bunkering the vessel.

(2) Should such pump perform the dual service of handling both ballast and transferring fuel oil to the settling tanks, one-half the space may be credited to propelling machinery space.

(g) Settling tanks. (1) Fuel oil settling tanks used solely for rendering crude oil fit for consumption in the main boilers are considered as part of the propelling machinery space.

(2) The permissible allowance for settling tanks is based on a 4 days' supply under full steam, which allowance must not exceed 1 percent of the vessel's gross tonnage.

(h) Engineers' stores and workshops. The engineers' stores, and/or workshops are regarded as part of the engine room, up to three-quarters of 1 percent of the gross tonnage, if in the engine room, open to same, or separated therefrom only by a screen bulkhead and located below the upper deck.

gines, then that length only which is requisite for containing and operating the boilers and machinery, is to be allowed, with the addition of such length as is necessary for the stoking or working of the fires when the furnaces are in a fore-and-aft direction.

(b) No such additional length is, however, required when the boilers are placed with the furnaces athwartship. The clear central space allowed between the boilers when the stoking is athwartship should be sufficient for this purpose. The point to which the after boundary of the length of the engine room is to be measured should be such as to provide sufficient space for the safe operation of the engine.

(c) The measurer should allow such length between the engines and boilers as may appear to him necessary for the safe working of the machinery.

§ 2.54

Boilers and engine in same compartment.

The boilers and engine are considered to be in the same compartment when there is a transverse bulkhead, screen or otherwise, through which the boilers project into the engine space, and where there is only sufficient space between the boilers and engine for the safe working of the machinery.

§ 2.55 Engine room measured in parts.

If the boilers and engine are entirely in separate rooms, or if there is a break or breaks in the bottom or side lines of the propelling machinery space resulting from a break or breaks in the double bottom or varying height of floors thereunder, or from side bunkers or other spaces not considered propelling machinery spaces, measure each room separately as a whole or in parts, according to the number of breaks in its bottom or side lines, and the sum of the several results shall be deemed to be the tonnage of the said spaces.

§ 2.56 Rule for measuring engine room.

(a) Space in hold amidship. When the propelling machinery (boilers and engine) space is in the hold amidship, and without a break in its bottom or side lines, measure its length between the foremost and aftermost bulkheads or limits of its length, excluding such parts, if any, not actually occupied by or required for the proper working of the machinery. Divide the length by 2 and measure 3 depths of the space, one

at each end and one at the middle of the length, taking the depths from the crown, or line of same, to the ceiling on the bottom frames or floor timbers, or to the inner plating (tank top) of the double bottom in the case of a steel vessel. Measure also a breadth at each end and at the middle of the length, the said breadths to be taken at onehalf their respective heights. Find the product of the length, mean breadth and mean depth, which product divide by 100 and the result shall be deemed the tonnage of the main space below the crown.

(b) Spaces between the crown and upper deck. Find the cubical contents of the space or spaces, if any, between the crown aforesaid and the upper deck, or line of same, which are framed in for the propelling machinery or admission of light and air thereto, by multiplying together the length, breadth and depth thereof. Divide the product by 100; add the quotient to the tonnage of the space below the crown and the result shall, subject to the provisions hereinafter contained, be deemed the tonnage of the space.

(c) Engine room in after end. When the propelling machinery space is located in the after end of the hold of a vessel and extends from side to side of same and has a continuous bottom line, divide its length into such an even number of parts as will give a common interval most nearly equal to that used in finding the tonnage of the hold in that part of the vessel; then proceed to find its contends by the use of areas of transverse sections taken at each end and at each point of division of its length. In other words, measure it by the same method as was used for finding the tonnage of that part of the hold in which it lies.

(d) Shaft tunnel and thrust recess. (1) In the case of screw propelled vessels in which the top of the shaft tunnel is flat, the tonnage of such tunnel shall be ascertained by dividing the product of its length, breadth and depth by 100.

(2) In like manner find the tonnage of the thrust recess or entrance to the shaft tunnel.

(3) If the space abaft the shaft tunnel extends from side to side of the vessel, find its tonnage by using the formula for measuring peak tanks. (See Figures 47 and 48 (§ 2.65).)

When

(e) Round top shaft tunnel. the top of the tunnel is practically semicircular in shape, find the area of a transverse section in two parts; first the lower part from the bottom of the trunk up to where the curve begins by multiplying the breadth by the applicable height, and then the semicircular part by taking half the area of a circle whose diameter equals the breadth of the tunnel. Multiply the sum of the two areas by the length and divide the product by 100. (See Figure 51 (§ 2.65), wherein B and H equal the breadth and height, respectively, of the lower part, and r equals the radius of the semicircular top.)

(f) Shaft space and thrust recess not cased. (1) When the shaft is not enclosed by a tunnel, the following rules should be observed in the case of a vessel with a single screw. The thrustblock space should be of such length and breadth as will permit of the proper care of the thrust-block and the height should not exceed 7 feet. The shaft space allowed should be of the dimensions of the usual tunnel suitable for the vessel and the height of this space should not exceed 6 feet.

(2) When the vessel is a twin screw and the space aft of the engines is open from side to side, the space should not be included in the engine room measurement for a greater height than 6 feet mean, and any space therein appropriated for stores or for any purposes other than the propelling machinery should be subtracted from the space to be included in the engine room. § 2.57 Engine room in small boats.

(a) When not bulkheaded off. In the case of a motorboat not having an engine room bulkheaded off from the rest of the hold, allow as engine space the space occupied by the engine and sufficient space on each side and end of it— say, about 2 feet-to permit the operator to handle it safely and efficiently; if sufficient space does not exist for such allowance then allow whatever space there is. Fuel tanks are not to be included in the said engine space.

(b) When bulkheaded off. If the engine room is bulkheaded off from the rest of the hold and is larger than is strictly required for safe and efficient handling of the engine, limit the engine space according to the said require