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The sail power should also be kept down in armored ships, so that the number indicating the power of the ship to resist inclination under her canvas, at deep draught, may not be less than 20.

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CHAPTER XVI.

Rule for Computing the Register Tonnage of all United States VesselsCalculation of Register Tonnage of the U. S. Steamers Omaha and Brooklyn.

Be it enacted by the Senate and House of Representatives of the United States in Congress assembled, That every ship or vessel built within the United States, or that may be owned by a citizen or citizens thereof, on or after the 1st day of January, 1865, shall be registered and measured in the manner hereinafter provided; also, every ship that shall be owned by a citizen or citizens of the United States shall be remeasured and registered upon her arrival, after said day, at a port of entry in the United States, and prior to her departure therefrom, in the same manner as hereinafter described: Provided, That any ship or vessel built within the United States, after the passage of this act, may be measured and registered in the manner herein provided.

SECTION 2. And be it further enacted, That the register of every vessel shall express her length and breadth, together with her depth, and the height under the third or spar deck, which shall be ascertained in the tollowing manner: The tonnage-deck, in vessels having three or more decks, shall be the second deck from below; in all other cases the upper deck is to be the tonnagedeck. The length from the fore-part of the outer planking, on the side of the stem, to the after-part of the main stern-post of screw steamers, and to the after-part of the rudder-post of all other vessels measured on the top of the tonnage-deck, shall be accounted the length of the vessel. The breadth of the broadest part on the outside of the vessel shall be accounted the vessel's breadth of beam. A measure from the under side of the tonnagedeck plank amidships to the ceiling of the hold (average thickness) shall be accounted the vessel's depth. If the vessel has a third deck, then the height from the top of the tonnage-deck plank to the under side of the upper-deck plank shall be accounted as the height under the spar-deck. All measurements to be taken in feet and fractions of feet; all fractions of feet to be expressed in decimals.

SEC. 3. And be it further enacted, That the register tonnage of a vessel shall be her entire internal cubic capacity in tons of one hundred cubic feet each, to be ascertained as follows: Measure the vessel in a straight line, along the upper side of the tonnage-deck, from the inside of the inner plank (average thickness), at the inside of the stem to the inside of the plank on the stern-timbers (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-timbers in the thickness of the deck, and also what is due to the rake of the stern-timber in one-third the round of the beam; divide the length so taken into the number of the equal parts required by the following table, according to the class in such table to which the vessel belongs:

TABLE OF CLASSES.

Class 1. Vessels of which the tonnage length, according to the above measurement, is fifty feet or under, into six equal parts.

Class 2. Vessels above fifty feet, and not exceeding one hundred feet, into eight equal parts.

Class 3. Vessels above one hundred feet, and not exceeding one hundred and fifty feet, into ten equal parts.

Class 4. Vessels above one hundred and fifty, and not exceeding two hundred feet, into twelve equal parts.

Class 5. Vessels above two hundred feet, and not exceeding two hundred and fifty feet, into fourteen equal parts.

Class 6. Vessels above two hundred and fifty feet, into sixteen equal parts. Then the hold being sufficiently cleared to admit of the required depths and breadths being taken, find the transverse area of such vessel at point of division of the length as follows:

Measure the depth at each point of division from a point at a distance of one-third the round of the beam below such deck, or, in case of a break, below a line stretched in continuation thereof, to the upper side of the floor-timbers, at the inside of the limberstrake, after deducting the average thickness of the ceiling, which is between the bilge planks and the limber-strakes; then, if the depth at the midship division of the length does not exceed sixteen feet, divide each depth into four equal parts; then measure the inside horizontal breadth, at each of the three points of division, and also at the upper and lower points of the depths, extending each measurement to the average thickness of that part of the ceiling which is between the points of measurement; number

RULE FOR COMPUTING THE REGISTER TONNAGE OF U. S. VESSELS. 63

these breadths from above (numbering the upper breadth one, and so on down to the lowest breadth); multiply the second and fourth by four, and the third by two: add these products together, and to sum add the first breadth and the last, or fifth; multiply the quantity thus obtained by one-third the common interval between the breadths, and the product shall be deemed the transverse area; but if the midship depth exceed sixteen feet, divide each depth into six equal parts, instead of four, and measure as before directed, the horizontal breadths at the five points of division and also at the upper and lower points of the depths; number them from above as before; multiply the second, fourth and sixth, by four, and the third and fifth, by two; add these products together and to the sum add the first breadth and the last, or seventh; multiply the quantities thus obtained by one-third the common interval between the breadths, and the product shall be deemed the transverse area.

Having thus ascertained the transverse area at each point of division of the vessel, as required above, proceed to ascertain the register-tonnage of the vessel in the following manner:

Number the areas successively one, two, three, &c., number one being at the extreme limit of the length at the bow, and the last number at the extreme limit of the length at the stern; then, whether the length be divided according to table, into six or sixteen parts, as in classes one and six, or any intermediate number, as in classes two, three, four and five, multiply the second and every even-numbered area, by four, and the third, and every odd-numbered area (except the first and last) by two; add these products together, and to the sum add the first and last if they yield anything; multiply the quantities thus obtained by onethird of the common interval between the areas, and the product will be the cubical contents of the space under the tonnage-deck; divide this product by one hundred, and the quotient being the tonnage under the tonnage-deck, shall be deemed to be the register tonnage of the vessel, subject to the additions hereinafter mentioned.

If there be a break, a poop, or any permanent closed-in space, on the upper decks, available for cargo, or stores, or for the berthing or accommodation of passengers or crew, the tonnage of such place shall be ascertained as follows:

Measure the internal mean length of such space in feet, and divide it into an even number of equal parts, of which the dis

tance asunder shall be most nearly equal to those into which the tonnage-deck has been divided; measure at the middle of its height the inside breadths, namely, one at each end and at each of the points of division, numbering them in succession, one, two, three, &c.; then to the sum of the end breadths add four times the sum of the even-numbered breadths, and twice the sum of the odd-numbered breadths, except the first and last, and multiply the sum by one-third the common interval between the breadths; the product will give the mean horizontal area of such space; then measure the mean height between decks, and multiply by it the mean horizontal area; divide the product by one hundred, and the quotient shall be deemed the tonnage of such space, and shall be added to the tonnage under the tonnage-decks, ascertained as aforesaid.

If a vessel has a third or spar deck, the tonnage of the space between it and the tonnage-deck shall be ascertained as follows: Measure in feet the inside length of the space at the middle of its height from the plank at the side of the stem to the plank on the stern, and divide the length into the same number of equal parts that the tonnage-deck is divided; measure (also at the middle of its height) the inside breadths of the space at each point of division; also the breadth at the stem and breadth at the stern; number them one, two, three, and so forth, commencing at the stern: multiply the second and all other even-numbered breadths by four, and the third and all other odd-numbered breadths (except the first and last) by two; to the sum of these products add the first and last breadth, multiply the whole sum by one-third the common interval between the breadths, and the result will give in superficial feet the mean horizontal area of such space; measure the mean height between the planks of the two decks, and multiply by it the mean horizontal area, and the product will be the cubical contents of the space; divide the product by one hundred, and the quotient shall be deemed the tonnage of such space, and shall be added to the other tonnage of the vessel, ascertained as aforesaid. And if the vessel has more than three decks, the tonnage of each space above the tonnage-deck shall be severally ascertained in the manner above described, and shall be added to the tonnage of the vessel ascer tained as aforesaid.

In ascertaining the tonnage of open vessels, the upper edge of the upper strake is to form the boundary line of measurement,

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