Page 255 - Rules of Navigation2020

radii thus measured, add them together, and the sum multiplied by 3.1416 shall be
deemed to the area of the section.

(Art.5) Number the transverse sections measured by one of these methods successively 1, 2,
3, etc. giving No 1 to the extreme limit of the length at the bow, and the last number

to the extreme limit of the length at the stern; then, whether the length be divided
according to the table into four or twelve parts, as in Classes 1 and 5, or any
intermediate number, as in Classes 2, 3 and 4, 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 quantity thus obtained by one-third of the common
interval between the areas, and the product will be the cubical contents of the space

under the tonnage deck. The tonnage of this volume is obtained by dividing it by 100,
if the measurements are taken in English feet and by 2.83 if the measurements are

taken in meters.
(1)
(Art.6) If the ship has a third deck, commonly called a 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 lining on the timbers at the stern, and divide the

length into the same number of equal parts into which the length of the tonnage deck
is divided, as above directed; measure ( also at the middle of its height ) the inside
breadth of its space at each of the points of division, also the breadth at the stem and

the breadth at the stern; number them successively 1, 2, 3 etc. commencing at the
stem, multiply the second and all the other even-numbered breadths by four, and the

third and all the other odd-numbered breadths ( except the first and last ) by two; to
the sum of these products add the first and last breadths, multiply the whole sum of

one-third of 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 of

such space, and multiply by it the mean horizontal area, and the product will be the
cubical contents of space; divide this product by 100, or by 2.83 if the measurements
are taken in meters, and the quotient shall be deemed to be the tonnage of such space,

and shall be added to the other tonnage of the ship ascertained as aforesaid; and if the
ship has more than three decks, the tonnage of each space between decks above the

1 ) In these rules the multiplier 0.353 may be used instead of the divisor 2.83 to give meters.
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