These may, perhaps, be considered the extremes of ship-building; and between these there is every grade of difference.
Tonnage and Carriage of Merchant Vessels.—The amount a vessel will carry in proportion to her tonnage, depends upon whether, and to what extent, she is full or sharp built. A sharp-built vessel of 300 tons' measurement, will carry just about her tonnage of measurement goods. A sharp-built vessel of 200 tons or under would probably carry less than her measurement; if over 400 tons, she would increase gradually to fifty per cent. above her measurement. A sharp-built vessel of 600 tons, is generally rated at 900 tons carriage. A full-built vessel of 300 tons, after the latest model of American freighting vessels, will carry 525 tons, or seventy-five per cent. above her measurement; and one of 500 tons would carry full double her measurement.
The following table may give a pretty fair average.
TONS OF MEASUREMENT GOODS.
| Tonnage. | Full built. | Sharp built. |
| 300 | (.75) 525 | (.00) 300 |
| 400 | (.80) 725 | (.40) 560 |
| 500 | (1.00) 1000 | (.50) 750 |
| 600 | (1.33) 1400 | (.50) 900 |
Proportions of Spars.—There is no particular rule for sparring merchant vessels; some being light, and others heavy sparred; and some having long topmasts and short lower masts, and others the reverse. The prevailing custom now is, to spar them lightly; the main yard being a little less than double the beam; and the others proportioned by the main. Most merchant vessels now have the yards at the fore and main of the same size, for convenience in shifting sails; so that the same topsail may be bent on either yard.
The following table, taken from the "Seamen's Manual," will show the average proportions of the spars of merchant vessels of the largest class, as formerly built.
Main-mast, two and a half times the ship's beam.
Fore-mast, eight ninths of the main-mast.
Mizzen-mast, five sixths of the main-mast.
Bowsprit, two thirds of the main-mast.
Topmasts, three fifths of the lower masts.
Topgallant masts, one half the length of their topmasts.
Jib-boom, the length of the bowsprit.
Main-yard, twice the beam.
Fore-yard, seven eighths of the main-yard.
Maintopsail-yard, two thirds of the main-yard.
Foretopsail-yard, two thirds of the fore-yard.
Crossjack-yard, the length of the maintopsail-yard.
Topgallant-yards, two thirds of the topsail-yards.
Mizzentopsail-yard, the length of the maintopgallant-yard.
Royal-yards, two thirds of the topgallant-yards.
Spritsail-yard, five sixths of the foretopsail-yard.
Spanker-boom, the length of the maintopsail-yard.
Spanker-gaff, two thirds of the boom.
For the thickness of the spars, the same book allows for the lower masts one inch and a quarter diameter at the partners, for every three feet of length; and nine tenths in the middle and two thirds under the hounds, for every inch at the partners. For the yards, one inch at the slings, and half an inch at the yard-arms, within the squares, for every four feet of the length. For the breadth of the maintop, one half of the beam, and of the foretop, eight ninths of the maintop.
The following are the proportions of the spars of the ship Damascus, before mentioned, built in 1839.
| Main-mast | 74 ft. | Head | 11 ft. | 6 in. | Size | 26 | in. |
| Fore-mast | 70 ft. | Head | 11 ft. | 6 in. | Size | 25 | in. |
| Mizzen-mast | 68 ft. | Head | 8 ft. | 6 in. | Size | 18 | in. |
| Main and fore topmasts | 41 ft. | Head | 6 ft. | 6 in. | Size | 14½ | in. |
| Mizzen topmast | 32 ft. | Head | 5 ft. | Size | 9½ | in. | |
| Main topgallant-mast | 23 ft. (15 ft. with 2 feet head.) | Size | 9½ | in. | |||
| Fore topgallant-mast | 21 ft. 14 ft. with 2 feet head.) | Size | 9½ |
in.
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