(c) A 2-foot rule with a hinge is required for taking the rake of the bow and stern and for other purposes.

(d) A carpenter's square will be found useful for setting the sliding rod perpendicular to the keelson.

(e) For taking the breadths in the hold which are beyond the reach of the measuring officers two lift rods will be needed, each about 8 feet long (made by joining two sections), one having a pulley at the end over which the tape may be drawn when the rods are held in position and the other an attachment for holding the ring at the end of the tape.

(f) For transferring the location of the stations or ordinates of the transverse sections from the deck to the keelson, and sometimes, for finding registered breadth, a plumb line and bob are needed.

(g) For measuring laden vessels for Panama or Suez Canal tonnage certificates, a girting galvanized chain of an approved make is required.

In addition to what are commonly known as masts, spars set up at the center line of the bridging at the top of king-posts of certain vessels for signals and wireless antennae, etc., are to be considered as masts. The number of king-posts and derrick posts, etc., independent of the supported masts are to be separately stated after the number of said masts; e. g., "Two masts and eight king-posts," or as the case may be. § 2.17 Ceiling, cargo battens, etc.

(a) Ceiling. Ceiling hereafter referred to is considered the permanent planking fitted directly on the inboard side of the frames, or floors, or the top of the double bottom. The maximum allowance for ceiling is 3 inches on the bottom and

3 inches on each side. When ceiling is found to be less than 3 inches thick, allow the actual thickness thereof; that is, take dimensions to the face of the ceiling so found. Depths and breadths shall not be decreased due to grounds supporting ceiling nor shall allowance be made for ceiling on the under side of deck beams.

(b) False ceiling. In small vessels with "false ceiling" in a portion of their cabins, in their holds, or forming a part of their seats or lockers, etc., therein, and which stands off from their framesthat is, not fitted to them as ordinary ceiling-take the breadths through the said "false ceiling" to the inner faces of the vessel's frames, deducting therefrom the thickness of the "false ceiling" on each side. If, however, there is a ceiling fitted on the frames in addition to the "false ceiling," take the breadths to the ceiling on the frames, making no allowance for the "false ceiling."

(c) Cargo battens, insulation. Paragraph (a) of this section applies to cargo battens (spar ceiling) and refrigeration insulation.

(a) The length measured on the tonnage deck, from the fore part of the outer planking (where it is rabbeted) on the side of the stem of wooden vessels, or fore end of lap of outer plating of steel or iron vessels, to the after side of the main sternpost, shall be accounted the vessel's register length. (See Figures 2 and 3 (§ 2.65).)

(b) In the case of screw vessels with no sternpost, take the length to the forward side of the rudder-stock or line of same extended through the deck.

(c) The register length of scows and barges, with a square bow and stern sloping up from the bottom to the deck, and with neither stem nor sternpost, is to be taken on the deck from the extreme point of the hull at the bow to the extreme point of the hull at the stern; that is, the over-all length of the hull, not including guards or rubbing strakes, is to be considered the register length of such vessel.

§ 2.19 Register breadth.

(a) A measure from the outboard face of the outer skin on one side to the same point opposite, taken at or below the

upper deck and at the widest part of the hull is the register breadth. (See Figure 4 (§ 2.65).)

(b) A practical method for finding the register breadth is, to add twice the sum of the depth of the vessel's side frames and thickness of outer skin, plus an allowance for thickness of ceiling, insulation or cargo battens if fitted, to the greatest tonnage breadth.

§ 2.20 Register depth.

(a) The register depth is taken at the middle of the tonnage length from the under side of the tonnage deck, or line of same, down to the top of the floors at the side of the keelson; or to the ordinary floor timbers or plates when fitted; or to the inner bottom plating (tank top) of a cellular double bottom; as the case may be, in a direction perpendicular to the keel.

(b) Should ceiling be fitted on the above mentioned bottom members, the register depth shall be measured to the top of same and to this dimension shall be added the height of grounds, battens or other type of support for the ceiling. (See Figures 4 and 5 (§ 2.65).)

(c) If the vessel is measured in parts, as explained later, the register depth is taken at one-half the tonnage length of the vessel.

§ 2.21 Upper deck to the hull.

The uppermost complete deck, which extends from stem to stern and from side to side at all points of its length and below which there are no openings through the hull as required in shelter deck spaces and also having its hatchways or other openings provided with means for closing them against the action of the sea and weather upon the space below enclosed by the sides of the vessel, making the said space a fit place for the stowage of general cargo, is to be considered the upper deck to the hull. § 2.22

Enumerating the decks.

In enumerating the number of decks, only those which are without such openings as exempt the spaces beneath from being included in the tonnage under the upper deck are to be considered. Other decks, if any, containing such openings as exempt the spaces beneath from in

clusion in tonnage should be separately described after the number of decks proper; e. g., "Two decks and shelter deck," or as the case may be. Partial decks, forward or aft, such as orlop decks, are not considered as decks. § 2.23 Register height.

The height from the top of the tonnage deck planking and/or plating to the underside of the planking and/or plating of the upper deck to the hull shall be deemed the register height of the upper deck to the hull above the tonnage deck.

[T.D. 66-57, 31 F.R. 4295, Mar. 11, 1966] § 2.24 Round of beam.

(a) The round of beam (camber) is the perpendicular distance down from the crown of the under side of the tonnage-deck plank or plating at the center to a line stretched athwart the vessel from end to end of the top of the beam and is to be ascertained at every place where it is to be used in the measurement. (See Figures 6 and 16 (§ 2.65).)

(b) The round of beam of the tonnage-deck, which must be known before taking the tonnage length, as well as before measuring the depths of the tonnage sections, may be taken either at the under side of the deck by stretching a small line tightly from end to end at the top of the beam, which will show the round or camber of the beam at the center; or it may be taken, if more convenient, at the upper side of the deck by stretching a line tightly across, held at equal heights from the deck at each side of the vessel, so as just to touch the crown of the deck at the middle line; then the distance from the deck to the line at the vessel's sides gives the round of beam. (See Figure 6 (§ 2.65).) It is necessary to take the round of beam at each point of division of the length except when the vessel has a flat deck or one practically so. In lieu of the above methods, it may be ascertained on the basis of one-fourth of an inch to the foot of beam at each section in iron or steel vessels of the usual camber of beam. This method is more accurate and easier of application than the others.

(c) When the round of beam is 0.15 foot or less, it may be ignored.

§ 2.25 Pitch of beam.

(a) In vessels whose tonnage deck has a pitch instead of a round from its side at the shell plating to its center, find the height of the pitch of the beam at each tonnage section. It may be done in any practical manner.

(b) The height of the pitch of the beam is the perpendicular distance from the apex at the under side of the tonnage deck plank or plating at the center of the deck down to a straight line from end to end of the top of the beam. (See Figure 7 (§ 2.65).)

§ 2.26 Tonnage deck.

(a) Except as to a vessel having its tonnage deck determined under the provisions of § 2.88(d), the tonnage deck is the upper deck to the hull in vessels having not more than two decks, and the second from the keel in vessels having more than two decks.

(b) If the tonnage deck consists of several partial decks extending with breaks from stem to stern, and if the partial decks are at different heights, the line of the lowest deck will be taken as the tonnage deck, and the headroom above such line under the higher deck or decks will be measured as a break.

(c) Engine and boiler casings, peak tanks and cofferdams are not considered as breaking the continuity of a deck. (See Figures 8 and 9 (§ 2.65).)

[28 F.R. 14553, Dec. 3, 1966, as amended by T.D. 66-57, 31 F.R. 4295, Mar. 11, 1966]

§ 2.27 Tonnage length.

The tonnage length is the longitudinal distance on the under side of the tonnage deck, or line of same from a point where the line of the inboard faces of the side frames, or ceiling thereon if any, intersects the side of the stem, to a point aft on the inboard face of the stern timber or cant frame, or ceiling if fitted thereon. (See Figures 10 and 11 (§ 2.65).)

§ 2.28 Depth of a transverse section.

(a) Depth. The depth of a tonnage section is a measurement taken at its proper point of division of the tonnage length, from a point at a distance below the tonnage deck equal to onethird of the round or one-half of the pitch of the beam, down to the upper side of the floor timbers or floor plates; or

bottom floors alongside the keelson; or longitudinals; or the tank top of a cellular double bottom, as the case may be.

(b) Ceiling. If ceiling is fitted on the bottom floor members, depths of transverse sections terminate on the upper face of the ceiling of average thickness. (See Figure 4 (§ 2.65).) For tonnage depths where ceiling is fitted on tank top, see Figure 5 (§ 2.65).

(c) Raised platform. In vessels with a raised platform in the bottom and no ceiling fitted on the bottom frame members, the depths are to be taken down through the platform to the upper side of the floor timbers or floor plates as described above, deducting therefrom the thickness of the ceiling of the platform in question.

(d) Depths in way of interruptions to tonnage deck. Should depths of transverse sections fall where the tonnage deck is interrupted, due to a break, hatches, etc., then depths are taken from the line of continuation of the tonnage deck.

(e) Rise of double bottom. In vessels having a double bottom the tank top of which, in way of tonnage sections, rises from the center line to the wings, the tonnage depth of each section will terminate at one-half height of the dead rise. (See Figure 12 (§ 2.65).)

(f) Fall of double bottom. In vessels having a double bottom the tank top of which, in way of tonnage sections, has a straight fall from the center line to the wings the tonnage depth of each section will terminate at one-half height of fall. (See Figure 13 (§ 2.65).)

§ 2.29 Tonnage depths.

(a) The tonnage depth. The depth generally referred to as "the tonnage depth" is located at the middle point of division of the tonnage length and is found in a manner similar to the other depths of transverse sections.

(b) Tonnage depth in a vessel measured in parts. Should a vessel be required to be measured in parts, and each part measured as a separate unit; then a tonnage depth shall be found for each part or unit at one-half its tonnage length. (See Figure 14 (§ 2.65).)

(c) Tonnage depth is the first depth measured. The tonnage depth governs the number of parts into which it and all

the remaining depths of the part in which said depth is located, is divided.

(d) Divisions of tonnage depth. If the tonnage depth at the middle of the tonnage length of the vessel or part of same does not exceed 16 feet, divide each depth into 4 equal parts; but if the depth at the middle of said length exceeds 16 feet, divide each depth into 6 equal parts.

(e) Intervals. The common intervals between the points of division of depths, also one-third common intervals are to be carried to the nearest hundredth of a foot.

(f) Purpose for dividing tonnage depths. Depths are divided to indicate points at which tonnage breadths are to be measured.

§ 2.30 Tonnage breadths.

(a) Breadths. An inside horizontal breadth is to be measured at each point of division of the depth marked on the sliding rods placed in position as directed in § 2.13 (b) and also at the upper and lower points of the depth. Extend each measurement to the inboard face of the ordinary frames, or line of same, or inboard face of ceiling, or battens, or insulation of average thickness if fitted. (See Figure 15 (§ 2.65).) Care must be taken that the sections shall be parallel to each other and at right angles to the axis of the vessel.

(b) Upper breadth. In finding the upper breadth of each transverse section make no allowance for the excess of the deck-beam shelves, etc., over the permissible thickness of ceiling, if any, thereunder.

Referring to Figure 16 (§ 2.65), observe that after the deck is laid the upper breadth (represented by the line U B) passes through the deck on each side. Hence, it is impossible to take it at its true position. In such cases take it on the deck, allowing within the extended line of frames the thickness of the ceiling if any on the frames under deck, as shown by line T B in the figure.

Owing to deck-beam shelves or other obstructions, it can be more conveniently and accurately taken here than under the deck, and, besides it will be only a few inches from its true position. In vessels which have upright sides the said breadth so taken will be correct, but in the case of vessels with inclining sides the necessary allowance must be made for the deviation of the sides from the upright in the few inches above the true position of the said breadth.

(c) Bottom breadths. Bottom breadths are taken only so far as the flat of the floor extends. (See B B, Figures 4 and 5; Figure 15; and B B, Figures 17 and 18 (§ 2.65).)

When bottom frames rise immediately from the keelson, or combined keel and keelson, and bona fide floor timbers or floor plates are not fitted, bottom breadths are equal to the breadth of keelson, or combined keel and keelson as the case may be. (See B B, Figure 19 (§ 2.65).)

The bottom breadths of transverse sections of vessels of longitudinal construction falling in the hold where there is no double bottom and where there is a dead rise of the bottom out to the sides of the vessel may be considered to be equal to that part of the bottom plating not affected by dead rise.

(d) Bottom breadths in case of rise or fall of double bottom. Bottom breadths falling in way of a double bottom the top of which rises or falls from the midship longitudinal plane to the wings are measured from and to the inboard end of the frame brackets (or ceiling thereon if fitted), connecting the double bottom with the frames.

(See B

B, Figures 12 and 13 (§ 2.65).)
§ 2.31 Measuring the tonnage length.

(a) The cubic capacity of the space below the tonnage deck is determined by use of the tonnage length together with the areas of a prescribed number of transverse sections as hereinafter described.

(b) To determine the extreme points of the tonnage length as indicated by §2.27 and T L in Figures 10 and 11 (§ 2.65), observe the following:

(1) Vertical bow and stern. In vessels having a vertical bow, also a vertical stern, both above and below the tonnage deck, measure horizontally the depth of frames, also the thickness of ceiling thereon if any, at the extreme forward and after ends immediately under the tonnage deck. Mark these measurements on the upper side of the tonnage deck, from the outer shell and in the direction in which the frames were measured. Then draw through the points thus obtained, lines parallel to the shell. The forward and after points of intersection of these lines indicate the points from and to which the tonnage length is to be measured.

(2) Raked bow or stern. In the case of vessels having a raked bow or stern at the level of the tonnage deck, the extreme points of the tonnage length are, when practicable, to be determined at the under side of the tonnage deck. The distance from these points to a hatch coaming, bulkhead, etc., should be measured and transferred to the upper side of the tonnage deck as indicated in Figure 20 (§ 2.65).

(c) Should it be impracticable to determine the extreme points of the tonnage length at the under side of the tonnage deck, and should the thickness of this deck be considerable, as in the case of a wooden deck, the rake of the bow or stern within the thickness of the deck is to be taken into account. This is done after having first proceeded as indicated in paragraph (b) (1) of this section by measuring the thickness of the tonnage deck and determining by means of a hinged rule, or any other instrument for finding angles under similar circumstances, the angle of the rake which the bow or the stern forms with the tonnage deck. Transfer thereafter this angle on the deck by drawing the lines A B C shown in Figure 21 (§ 2.65), A B represents the upper side of tonnage deck and B C the after side of the stem or the inside of the shell at the stern, as the case may be. The perpendicular B D represents the thickness of the tonnage deck. The points T, L, in Figures 10 and 11 (§ 2.65) marked on the upper side of the tonnage deck are then to be moved forward at the stern or aft at the stem, as the case may be, for a distance equal to D E, representing the rake within the thickness of the deck.

(d) It should be borne in mind that the condition for applying the method of setting out the angles on the upper side of the tonnage deck is that the stem or stern have the same angle of rake above and immediately below the tonnage deck. If the angle of rake at or immediately below the tonnage deck is a different one, then this last angle must be used.

(e) Should a vessel as referred to in paragraph (b) (2) of this section have a square bow or stern, it will be necessary to make a correction for camber where such exists. This is done by increasing the thickness of the deck B D in Figure 21 (§ 2.65) by one-third of the round or one-half of the pitch of beam at the extreme point of the tonnage length.

§ 2.33

Transfer of location of sections to keelson.

(a) The tonnage length having been ascertained and the number of sections to be measured and the interval between them determined, a line is then to be extended down the main hatchway, at the middle line of the vessel, in a perpendicular direction.

(b) The distance of the midship tonnage section is then to be set off from this line in the same direction on the keelson, which gives the position of the midship section on the keelson, and the positions of the other sections are obtained on the keelson by setting off forward and abaft the midship section the common interval between sections as already determined.

The position of the midship tonnage section may be determined by any other practical means.

§ 2.34 Transverse areas, rule for finding.

(a) Assuming the tonnage length exceeds 250 feet requiring that it be divided into 16 equal parts, and the tonnage depth at the middle of the tonnage length exceeds 16 feet, requiring it to be divided into 6 equal parts:

(1) Measure the depth at each of the 15 points of division of the length as required, also at the extreme forward point (Section 1) and at the extreme after point (Section 17) of the length. (See Figure 22 (§ 2.65).)