Length of the keel for tonnage, which results from the extreme breadth, and a length hereafter given.
Depth in hold, which must be always regulated by the properties required of the vessel.
Burtben in tons, resulting from the extreme breadth and length of the keel for tonnage, being multiplied into each other by a rule given hereafter.
Now these are called the principal di mensions, which we will endeavour to de scribe, with their concomitant circum stances, in their above order ; and, first, the length on the gun-deck ; this in ships of war must ever contain sufficient dis tance between the perpendiculars for all the ports, and room between each port for working the guns, and what may be required at the extremities, such as the manger at the fore-part and abaft, room for the after-port to come clear of the wing transom knee, &c. It will also ap pear evident, that the distance between each port in the clear must contain space sufficient for two frame timbers and the filling timbers between, and the room or openings between the timbers. Thus we find by established practice the dis tance between, and size of, the ports, in the following class of ships in the navy, are as follow : The next dimension is the extreme breadth, and without repeating the pro portions which various authors have men tioned, all alike erroneous as to fixed data, we will give the extreme breadths of the above ships, which upon trial have been found to answer their intended pur poses by that construction.
The length of the keel for tonnage, as was before observed, is produced from the former dimension, and a length given by a rule, although long established, is very defective, and the tonnage or burthen of the vessel, as it is sometimes called, is said to be produced therefrom. It may be therefore readily seen, that those two dimensions only cannot possibly give any true burthen, for those two dimensions may be alike in two vessels, of the great est difference in their construction ima• ginable, for one vessel may be so con structed from the same dimensions, as to be very sharp under her load draught of water, with a very quick rising, to possess the requisite qualities for fast sailing, as the sloop of war ; while an other vessel keeping the dimensions the same, may be constructed as full under water as the most burthen some merchant ships. Sometimes the production of this rule is called builder's tonnage, as a contradistinction to the true tonnage, and by this result builders are paid a certain price per ton for build ing any vessel.