To find the tonnage and burthen of any ship or vessel, importing or exporting brandy, other spiriteous liquors, or any other goods whatsoever into or from this kingdom, or hovering upon the coasts thereof; and where the owner or proprietor, or other person, shall be entitled to any bounty or allowance, according to the tonnage of any ship or vessel; and in all other cases whatsoever where the tonnage or burthen of any ship or vessel shall be necesary to be ascertained or known, by an act or acts of parliament, made or hereafter to be made, concerning the customs, excise, or salt-duty; the rule for admeasuring such ships or vessels shall be be [sic] as follows; that is to say:
The length shall be taken on a straight line along the rabbet of the keel of the ship, from the back of the main stern-post to a perpendicular line from the fore-part of the main-stern under the bowsprit; from which, subtracting three-fifths of the breadth, the remainder must be esteemed the just length of the keel to find the tonnage; and the breadth shall be taken from the outside of the outside plank, in the broadest place in the ship, be it either above or below the main wales, exclusive of all manner of doubling planks that may be wrought upon the sides of the ship: then, multiplying the length of the keel by the breadth so taken, and that product by half the breadth, and dividing the whole by ninety-four, the quotient will be deemed the true contents of the tonnage. According to which rule, the tonnage of all such ships and vessels shall be measured and ascertained, any thing in the said recited act of the sixth of George I., or any other act or acts of parliament, to the contrary notwithstanding.
N.B. This rule is not to alter the measurement of coal-vessels.
Shipwrights generally make use of the following rule; multiply the length of the keel by the greatest breadth, and that product by half the breadth: then divide the last product by 94, and the quotient will give the tonnage required, for merchant ship; but, for men of war, the last product should be divided by 100.
[13 Geo III, c 74]
Transcribed by Lars Bruzelius
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