The Seaman's Friend / Containing a treatise on practical seamanship, with plates, a dictionary of sea terms, customs and usages of the merchant service

by Richard Henry Dana

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.
Mizzen topgallant-mast	17 ft. 11 ft. with 18 in. with 2 feet head.)
Main and fore yards	60 ft. yard-arms 2 ft. 6 in.
Main and fore topsail yards	48 ft. yard-arms 3 ft. 6 in.
Main topgallant yard	37 ft. yard-arms 2 ft.
Fore topgallant yard	34 ft. yard-arms 2 ft.
Main royal yard	27 ft. yard-arms 1 ft. 6 in.
Fore royal yard	24 ft. yard-arms 1 ft. 6 in.
Main skysail yard	17 ft.
Fore skysail yard	15 ft.
Cross-jack yard	44 ft. yard-arms 2 ft.
Mizzen topsail yard	35 ft. yard-arms 2 ft. 9 in.
Mizzen topgallant yard	25 ft. yard-arms 1 ft. 6 in.
Mizzen royal yard	16 ft.
Mizzen skysail yard	10 ft.
Bowsprit, out-board	27 ft.				Size	26	in.
Jib-boom	42 ft.	Head	3 ft.		Size	14½	in.
Flying jib-boom	40 ft.	Head	3 ft.	6 in.
Main pole	12 ft., 10 above royal-mast, 5 in. in cap.
Fore pole	11 ft., 9 above royal-mast, 4½ in. in cap.
Mizzen pole	9 ft., 7 above royal-mast
Spanker-boom	40 ft.
Spanker-gaff	30 ft.
Swinging-booms	40 ft.
Topmast studdingsail-booms	34 ft.
Topgallant studdingsail-booms	27 ft., yards for do. 17 ft.

Placing the Masts.—For a full-built ship, take the ship's extreme length and divide it into sevenths. Place the foremast one seventh of this length from the stem; the mainmast three sevenths from the foremast, and the mizzenmast two sevenths from the mainmast. If a vessel is sharp-built, and her stem and stern-post rake, her foremast should be further aft, and her mizzenmast further forward, than the rule of sevenths would give. A common rule for placing the foremast, is to deduct three fifths of a ship's beam from her length, for the curvature of the keel forward, which is called the keel-stroke, and place the mast next abaft the keel-stroke.

Size of Anchors and Cables.—Various rules have been adopted for the weight of a ship's anchors. A vessel of 100 tons will generally have a best bower of 6 cwt. and a small bower of 5 cwt.; the weight of both being eleven pounds to a ton of the vessel. As a vessel increases in size, the proportion diminishes. A vessel of 700 tons will usually carry a best bower of 27 cwt. and a small bower of 24 cwt.; the weight of both being seven and a half pounds to a ton of the vessel. The stream should be a little more than one third the weight of the best bower. The anchor-stock should be the length of the shank; its diameter should be half that of the ring, and its thickness one inch at the middle and half an inch at each end for every foot in length. Chain cables are usually ninety fathoms in length, for large-sized vessels, and sixty for small vessels, as schooners and sloops. The regulation of the United States Navy for chain cables, is one inch and a half for a sloop of war, and one and a quarter for brigs and schooners. In the merchant service, a ship of 400 tons would probably have a best bower cable of one and five sixths, and a working bower of one and a quarter inches. A ship of 700 tons would have a best bower of one and five eighths, and a working bower of one and a half inches. Chain cables have a shackle at every fifteen fathoms, and one swivel at the first shackle. Some have two swivels; and formerly they were made with a swivel between each shackle.