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THE EQUIPPING AND HANDLING
UNDER SAIL OR STEAM.
FOR THE USE OF THE
UNITED STATES NAVAL ACADEMY.
COMMODORE S. B. LUCE, U. S. NAVY.
REVISED AND ENLARGED BY
LIEUTENANT AARON WARD, U. S. NAVY.
WITH ILLUSTRATIONS DRAWN BY
LIEUTENANT S. SEABURY, U. S. NAVY.
VAN NOSTRAND COMPANY,
23 MURRAY STREET & 27 WARREN STREET.
Copyright, 1834, by D. Von Nostrand
SMITH & MCDOUGAL,
PREFACE TO THE REVISED EDITION.
THIS work, originally compiled in haste to meet the
immediate wants of the Naval Academy, and revised at different periods under the pressure of other duties, has not merited the place it has so long occupied as a text-book.
Of this the compiler has been fully conscious. Its deficiencies were so numerous and so obvious and the circumstances under which it was prepared so well known that apologies seemed altogether superfluous.
It was for long years supposed, moreover, that some more competent hand would have undertaken an entirely new work.
Finding this expectation not realized, Lieutenant Aaron Ward has kindly consented to undertake the task of revision. He has performed his work intelligently and well, leaving out what was obsolete, introducing much new material, rearranging the subjects, and bringing the text down to the present time.
He has been ably assisted by Lieutenant Samuel Seabury, who has contributed some four hundred new illustrations and revised the old ones.
S. B. LUCE,|
Commodore, U. S. N.
NEWPORT, R. I., Feb. 1883.
GRATEFUL acknowledgments are due to those whose contributions to the text have enhanced the value of this work.
Commander F. V. McNair has permitted the use of his pamphlet on Seamanship Drills.
The chapter on the Laws of Storms is taken principally from the lecture of Lieutenant-Commander Thomas Nelson, Vol. V, Proceedings U. S. Naval Institute.
Chapter XIX. is practically a reprint of Lieutenant D. Delehanty's pamphlet: "Cadet Midshipman's Manual."
Chapter XXXV. has been prepared from notes furnished by Lieutenant-Commander Z. L. Tanner, together with data from the lectures of Constructor R. H. White, R. N., and from the professional pamphlets of the German Admiralty on steamers and screw propulsion.
The suggestions made by Boatswain Robert Anderson, U. S. N., have been of special importance. Getting a lower yard on board, sending down a lower yard inside of rigging, rigging derricks, and carrying out anchors between two cutters in shoal water, are described from actual work performed under his direction.
To Commander Taylor, Lieutenants Berry, Nazro, and Holman, U. S. N., and to many other officers, sincere thanks are tendered for their assistance and suggestions in the revision of the proofs.
Lieutenant, U. S. N.
||-THE COMPASS-THE LEAD-THE LOG
||-KNOTTING AND SPLICING
||-CARRYING OUT ANCHORS
||-DUTIES OF MIDSHIPMEN
||-PORT DRILLS AND EVOLUTIONS
||-RULES OF THE ROAD
||-GETTING UNDER WAY UNDER SAIL
||-MAKING AND TAKING IN SAIL
||-WORKING TO WINDWARD
||-LAWS OF STORMS
||-IN A GALE
||-SHIFTING SAILS AND SPARS
||-COMING TO ANCHOR
||-HANDLING VESSELS UNDER STEAM
||-GETTING ON SHORE-LEAKING
||-THE LIFE-SAVING SERVICE
||-ROPE-MAKING-TABLE OF DIMENSIONS OF ROPE
||-CUTTING AND FITTING BLOCK STRAPS
||-TURNING IN OLD-FASHIONED DEADEYES-RULES FOR SIZE OF SHROUDS
||-STAYING MASTS BY-USE OF BATTENS
||-TABLES OF FLAX AND COTTON CANVAS
||-MANAGEMENT OF OPEN BOATS IN SURF
||-ROUTINE-PREPARING SHIP FOR SEA
||-TARRING DOWN-SCRAPING SPARS-PAINTING SHIP
||-IN A TIDEWAY UNDER SAIL
||-TENDING SHIP AT SINGLE ANCHOR-FIRE BOOMS
||-TURNING EXPERIMENT-METHODS OF DETERMINING TACTICAL DIAMETERS
||-TANNER SOUNDING MACHINE
||-SERVICE BUGLE CALLS
GENERAL REMARKS ON THE HULL, SPARS, AND SAILS.-DEFINITIONS.
Wooden ships are usually built on stocks and launched on ways, which are inclined planes leading to the water's edge. Sometimes vessels are built in docks, which are artificial basins with level floors, shut off from outside waters by gates or by a single dam known as a caisson. These gates are water-tight and can be opened or closed; the dock is supplied with means for pumping out the water or letting it in.
The lowest fore and aft piece which forms the foundation of a ship is called the keel (Plate 1, No. 1). It is of live-oak, or elm, and made of several pieces, the joints of which are known as scarphs.
To receive the edge of the first row, or strake, of outside planking, called the garboard strake (2), the keel is scored throughout its length, the score being styled a rabbet (3).
To protect the main keel from injury in grounding there is fitted under it a false keel (4), bolted on after the bolts which secure the frames to the main keel are clinched.
The forward end of the ship is formed of the stem (5), usually of live-oak, and inclining forward from the keel. A rabbet, similar to the one scored in the keel, is cut into the sides of the stem and receives the forward ends of the outside planking, which are called the fore hood-ends.
The stem is backed and strengthened by the apron (6), placed abaft it, and by the deadwood (7).
Deadwood consists of timbers that fill the spaces where, owing to the shape of the vessel, the floor-timbers have to be discontinued.
Inside of the forward deadwood and the apron is the stemson (8), a large knee which joins the apron to the upper part of the deadwood.
The after-end of the ship is bounded by the stern-post (9), usually of live-oak, which stands perpendicular to the keel or slightly inclined aft. It is fitted like the stem with a rabbet on each side to receive the after-ends of the outside planking, or after-hoods, and it is strengthened by the introduction of a stern-post knee (10), inner post (11), and the after-deadwood (12). Above the latter is the after-deadwood knee (13).
Screw vessels have generally two stern-posts; the after one, which carries the rudder, is called the rudder-post.
The joining of the stern-post to the keel is effected by tenons and bolts.
The frames (14) form the ribs of the ship. They stand mostly at right angles to the keel and each is formed of two parts joined together, each part being in itself made up of several pieces. The lowest portions of a square frame are called the floor-timbers; above these come the futtocks, then the long or short top-pieces. The starboard and port side of each frame form one continuous piece.
Where, owing to the form of the ship, the frames do not stand at right angles to the keel, they are called cant frames.
The following parts of the ship serve to secure the above-mentioned portions together and give the structure stiffness and strength; viz., the keelsons, breast-hooks (15) and stern-hooks (16), outer and inner planking, beams (17) and diagonal braces.
The main keelson (18) is a fore and aft timber which is laid directly over the keel on the floor-timbers and may extend beyond the latter and over the deadwood, forward and aft. The keelson is bolted through frames, keel, and deadwood. There are usually additional keelsons at each side of the main keelson, known as sister keelsons (20). There are also boiler or bilge keelsons to support the boilers (19). Bilge-keels are exterior keels bolted on to the bottom of the ship on either side of and parallel to the main keel, and at some distance from the latter, to prevent rolling in vessels of certain form.
To hold the two sides of the ship together in the forward and after ends, where the frames have no floor-timbers crossing the keel, owing to the form of the ship, there are worked in knee-shaped, horizontal timbers, either with a natural curve, or formed of two or more pieces backed by an iron or wooden knee. These curved supports, secured to either side of the ship, are termed breast-hooks (15) forward and stern-hooks (16) aft; when they support a deck they are called deck-hooks.
The outer planking of a ship is formed of a number of oak planks of varying thickness, but nearly parallel when placed in position over the frames.
To check marine growth on the bottom of vessels and the consequent decrease of speed, all wooden vessels of war are sheathed with copper from the keel to a point some distance above their line of flotation, or "water-line."
Inner planking. This planking is not continuous, as in the case of outside planking, and in different parts of the ship is called by different names. It is known as the limber-strakes (21) nearest the keelson. These strakes extend along the bottom of the ship on either side of the
keelson. As the planking is carried up the side beyond the limber-strakes it is known as the ceiling (22); following it up higher we find projecting ledges, called shelf-pieces, or clamps, placed inside the frames to receive the deck-beams.
The deck-beams (17), extending from side to side of the ship, holding the sides together, form the support for the deck-planking. The beams are supported by posts or stanchions (23) in their centre, and by clamps at each end. They are joined to the sides of the ship by iron or wooden knees, known as hanging (24), lodging (25), lap (26), or dagger (corruption of diagonal) knees, from their positions and form.
The waterways (27) are timbers set in the side over the tops of the deck-beams and bolted to these and to the frames at the side.
Decks are of oak, teak, or yellow pine, and are spiked to each deck-beam over which they pass.
Vessels owe much of their strength to the use of diagonal trusses or braces, of metal, secured inside of the frame-timbers and forming a net-work which binds the frames firmly together.
To the above outline of the parts of the hull is appended a list of prominent interior fittings and of the terms used in describing them:-
Aft. At or near the stern of the ship.
After passage. Usually a space in the after orlop of frigates, being a passageway to the different store-rooms on that deck.
Air-port. Hole cut in ship's side to give light and air to berth-deck. Usually circular.
Amidships. In or near the middle of the ship.
Apron. A timber secured in rear of the stem to strengthen it at the joint of upper and lower stem-pieces.
Athwartships. In the direction of the ship's breadth.
Bag-room. Where clothing-bags of crew are stored. Usually forward on the berth-deck or leading off of fore-passage.
Ballast. Stone or iron placed in the hold to bring the ship down to her proper line of flotation and give stability.
Beams. Timbers that extend from side to side, supporting the decks.
Bee-blocks. Clamps bolted to the bowsprit through which reeve the fore-topmast stays.
Belaying-pin. A pin of wood or metal at the side of the vessel or on the masts, around which a rope is fastened or belayed.
Bends. The thickest outside planking, extending from a little below the waterline to the lower gun-deck ports.
Berth-deck. The sleeping and mess-deck of the crew and officers of a ship.
Bibbs. Pieces of timber on either side of the mast to which the trestle trees are secured.
Bilge. The flat part of a ship's body on each side of the keel.
Bilge-keels. Long pieces of wood or iron affixed to ship's bottom to lessen the rolling motion.
Bill-board. A ledge on the ship's bow to receive the fluke of the anchor
Binnacle. A box containing the ship's compass.
Bitts. Large vertical timbers projecting above the deck to secure the ship's cable, also vertical posts to secure the main-tack, main-sheet, etc., according to location.
Boat-chocks. Blocks of wood shaped to receive the bottoms of boats, when hoisted in.
Bolsters. Rounded blocks of wood filling the angle between the trestle-tree and the mast, to prevent chafing of the rigging against the former.
Bolts. Pieces of iron or other metal used in fastening parts of the ship together.
Booby-hatch. A small hatchway, or the covering or companion of such an aperture.
Boom-iron. Iron rings secured to one yard or spar, to support another spar, which passes through the iron. Such are the studding-sail boom-irons on the lower and top-sail yards.
Bowsprit-bed. The part of the stem on which the bowsprit rests.
Bread-room. The store-rooms in which are kept the ship's allowance of hard-bread, etc. Usually situated in the after orlop.
Break of Forecastle. Where the rise of the forecastle towards the waste of the ship, ends. Commonly used to define the after side of a top-gallant forecastle.
Break of Poop. Where the rise of the poop towards the waist, ends. Commonly used in speaking of the forward end of the poop.
Breast-hooks. Knees, or an assemblage of timbers, set in the bows of ships and secured on either side to the timbers of the bow.
Bridle-ports. The ship's forward gun-ports. Through these ports are led the bridles of tow-lines or warps.
Bridge. A light structure extending across the ship above the spar-deck, to afford the officer of the deck or lookout a place for observation.
Bucklers. Shutters used in closing hawse-pipes (hawse-bucklers), or filling the
circular opening of half-ports when there is no gun in the port (port-
Bulk-heads. Partitions that divide off different parts of the ship.
Bulwarks. The sides of the ship above the upper deck.
Bumpkin. A projection of wood or iron from the bow or quarter, to give proper angle for the lead of the fore-tack or main-brace.
Cabin. The quarters of the commanding officer of a ship. On the gun-deck of a ship with flush spar-deck, or under the poop (poop-cabin) of a single-decked vessel or one having a poop in addition to a covered gun-deck. In the latter case the gun-deck cabin is usually occupied by a flag officer.
Cable-tier. Formerly platforms on which the ship's cables were coiled. At present understood to mean light platforms in the wings where spare rigging is stowed.
Cant-frames. Frames, forward and aft, which are not at right angles to the central fore and aft line of the vessel.
Cap. A joint fitted over the heads of masts to support the next higher mast, which passes through a hole in the cap.
Cap-shore. A stout upright which supports the forward edge of the lower cap.
Capstan. A barrel of wood or metal that revolves horizontally on a spindle;
is used with capstan-bars or moved round by steam to raise heavy weights,
weigh anchor, etc.
Carlings (28). Short timbers running fore and aft, connecting the beams.
Cat-head. An iron or wooden projection from the ship's bow to raise the anchor clear of the water.
Caulking. Filling the seams of a ship with oakum or cotton.
Cavil. A large wooden cleat used for belaying.
Ceiling. Portions of the inside planking of a ship.
Chains (see Channels). Chain chests. Lockers in the channels for the storage of wash-deck gear.
Chain-lockers. Receptacles for the chain cables of the ship, usually forward of the main-mast in the main-hold.
Chain-pipes. Iron linings of the holes through which the cables are led in passing from one deck to another.
Chain-plates. Iron plates for securing lower dead-eyes to ship's side.
Channels. Ledges of plank projecting from the side to give additional spread to the lower shrouds.
Chess-trees. Pieces of timber bolted in the top-sides, with sheaves for fore and main sheets, after guys. etc. Those for the fore and main sheets are known also as fore and main sheet "chocks."
Cleats. Pieces of wood with projecting arms, used for belaying ropes.
Coaming. A raised boundary to hatchways, to keep water from getting down, etc.
Cockpit. A space below the after hatchway under the berth-deck; usually the forward end of the after passage.
Compressor. In its simplest form, an iron lever fitted below each chain-pipe, the chain is controlled when running out by being, jammed between the compressor arm and edge of the chain-pipe.
Counter. The rounding of the stern over the run.
Cross-trees. Thwartship timbers supported by the bibbs and trestle-trees to sustain the frame of the top constitute the lower cross-trees. Top-mast cross-trees resting on the top-mast trestle-trees, extend the top-gallant shrouds.
Cutwater. The forward part of a ship's prow, forming the forward edge of the stem.
Dagger-knee. A knee which is inclined diagonally, usually to clear a port. Davits. Cranes projecting from the ship's side to hoist boats, etc.
Deadeye. A round flattish wooden block encircled by an iron "strap" and pierced with holes to receive a laniard by means of which rigging and stays are set up taut.
Dead-wood. Timber built up on top of the keel to give solid wood for supporting the heels of cant frames.
Decks. The different platforms of ships.
Dispensary. The ship's pharmacy, usually placed on starboard side of berth-deck forward of warrant officers' rooms, may also be in or near sick-bay.
Dolphin-striker. A small spar projecting downward from below the bowsprit
to extend certain rigging of the head-booms and keep the latter in place.
Eye-bolt. A projecting bolt of which the head is fashioned into an eye, used
for hooking tackles, etc.
Fid. A bar of iron or wood which passes through a fid-hole in the heel of a mast and rests on the trestle-trees on either side.
Fife-rail. Rails placed around each mast, fitted with belaying-pins to belay ropes.
Fish-davit. A movable piece of timber or iron projection, used to raise the fluke of an anchor and place it on the bill-board.
Fishes. Pieces of wood or iron used in effecting temporary repairs with injured masts, yards, etc.
Floor-timbers. Timbers of the frames which lie directly across the keel. Fore and Aft. Lying in the direction of the ship's length.
Forecastle. The upper-deck of a man-of-war forward of the after part of the fore-channels.
Fore-foot. The forward end. of the keel.
Fore-hold. The forward part of the hold, usually extending from abaft the fore-passage to about midway between fore and main masts.
Fore-passage. A passageway below the berth-deck leading to the general store-room and with entrances on either side to various special store rooms, sail-room, etc.
Fore-peak. The narrow part of a vessel's hold close to the bow and under the
lowest deck, often accessible only from the general store-room.
Funnel. An iron band at a mast-head around which the rigging fits.
Futtock-plates. Iron plates to which the deadeyes of the topmast rigging
and futtock-shrouds are secured.
Futtocks. Timbers of the frame between the floors and top-timbers.
Gammoning. The lashing or iron strap by which the bowsprit is secured to the stem.
Gangway. The spar-deck on each side of the booms between the quarter-deck and forecastle. Also an open space through the bulwarks as a passageway in and out of the ship.
General Store-room. Is situated below the berth-deck and at the forward end. of the fore-passage.
Gooseneck. A bent piece of iron used to connect a boom to a mast by entering an eye-bolt or clamp, and capable of movement at the curve.
Grating. An open latticed covering for hatches, etc.
Gripe. A piece bolted on forward of the stem, forming the lower end of the cut water.
Gun-deck A covered deck of a man-of-war carrying the whole or a portion of her battery. When the guns are carried on the upper-deck, its name as spar-deck remains unchanged.
Gun-room. Obsolete expression for the quarters of the commissioned officers.
Gunwale. The covering-piece of the heads of the timbers in a small vessel, or boat.
Half-deck. That part of the gun-deck between the main and mizzen masts on each side.
Hammock-nettings. Trough-shaped receptacles along the rail on either side, in which the hammocks are stowed. A net-work of ropes was formerly used for this purpose, hence the term; other nettings will be described, as used.
Hanging-knee. Knee placed vertically under a deck-beam.
Hatch. An opening in a deck, forming a passage from one deck to another, and into the holds.
Hawse-buckler. A plate used for closing the opening of the hawse-hole.
Hawse-holes. Holes in the bows of the ship through which pass the cables.
Hawse-pipe. Iron lining of the hawse-holes to take the chafe of the cables.
Hawse-plug. Plugs which fill the hawse-pipes to prevent the entrance of water
when the cables are unbent. Usually made of canvas and stuffed, then
Head-board. Boards placed at the forward and after ends of the hammock-nettings.
Helm. Strictly, the bar by means of which the rudder is moved from side to side. Usually understood to mean the rudder, tiller, and wheel, or the whole of the steering arrangement.
Hold. The interior part of ship in which the stores or cargo, etc., are stowed. In a man-of-war if there are two holds the forward one is called the fore-hold and the after one, whatever its position, the main hold.
Horse-block. A small raised platform abreast the mizzen-mast, for the use of the officer of the deck when the ship is not supplied with a bridge.
Hounds. A projection on a mast for the trestle-trees to rest upon.
Hull. The main body of the ship.
Inboard. In the interior of the ship, as distinguished from outboard.
Keelson. A timber in the interior of the ship bolted on over the keel and floor timbers.
Knight-heads. Strong uprights on each side of the upper part of the stem to strengthen the bow and support the bowsprit.
Ledges (29). Light beams, parallel to the deck-beams butting on the clamps and carlings.
Light-boxes. Frames in which are set the side-lights of a vessel when under way.
Limbers. Gutters on each side of the keelson to allow the water to pass into the pump-well. Limber-boards, the covering of the limbers.
Life-buoy. An apparatus for the assistance of those who may fall overboard.
Locker. A drawer or chest that may be closed with a lock. Shot-locker, a
compartment in the hold for storing shot; chain-locker, a similar compartment for the chain-cables.
Magazine. The store-room for the ship's powder, usually aft, under the wardroom, although many ships have two magazines, in which case one is forward and near the fore-passage.
Main-deck. A name given to the gun-deck of a vessel-of-war, and to the upper gun-deck of a two-decker.
Main-hold. That portion of the hold which extends from a short distance forward of the main-mast to the break of the orlop-deck.
Manger. Part of the deck divided off forward to prevent any water from running aft that may enter through the hawse-holes.
Manger-board. A plank running across the deck a short distance abaft the hawse-pipes, the after boundary of the manger.
Mast-coat. A canvas-covering fitted around the mast and over the wedges to prevent leakage around the mast.
Naval-pipe. Same as chain-pipe.
Oakum. Old rope picked to pieces, like hemp, used in caulking.
Orlop-deck. Usually a half-deck extending aft from the main-hold, a distance depending greatly upon the shape of the after body.
Outboard. On the outside of the ship, in contradistinction to inboard.
Partners. The framing around a mast-hole, to take the direct strain of the mast and mast-wedges.
Pawl. An iron arm on a capstan to keep it from recoiling.
Pin-rail. A railing on each side of the ship abreast of the masts, fitted with belaying pins for securing ropes.
Pay. To pay a seam is to pour hot pitch and tar into it after it has been caulked.
Poop. A deck raised above the after part of the spar-deck, reaching forward to the mizzen-mast.
Port. An opening cut in the side of the ship through which a gun may be discharged.
Port. The left side of a ship looking forward, as distinguished from starboard.
Pump-well. The part of the bilge upon which the suction of the pump acts directly.
Quarter-deck. Usually that part of the spar-deck which extends from the stern to the main-mast.
Quarter-gallery. Projections from the quarters of a vessel.
Rake. The inclination of a mast, etc., from a perpendicular direction to the keel.
Riding-bitts. The bitts around which the ship's cables are taken.
Ring-bolts. Eye-bolts having a ring through the eye of the bolt.
Rudder. The instrument by which a ship is steered.
Run. The narrowing of the after part of the ship.
Sail-room. Storage-room for spare sails, hammocks, and sail-maker's stores. In modern ships usually opens into the after-passage; some vessels have forward sail-rooms in fore-passage.
Sampson-knee. A heavy timber forward of the riding-bitts which serves to strengthen the latter.
Shell-room. Storage-room for explosive projectiles; when but one on board, is usually under the orlop near the after-hatch.
Shore. A post or timber used as a temporary support.
Sick-bay. The hospital of the ship, usually situated forward on the berth-deck.
Scuppers. Holes cut through the waterways and side to allow water to run off the decks.
Scuttle. A small circular aperture in a deck not intended for the passage of persons, through which powder, etc., may be passed from one deck to another.
Sheathing. Usually understood to mean a covering of copper, felt, etc., placed over a portion of the ship's surface to protect it. Copper sheathing covers
the immersed part of a ship to protect it from marine growth.
Spar-deck. The upper deck of a ship-of-war.
Spirketing. The inside planking of a ship extending from the lower edges of the gun-ports to the waterways.
Spirit-room. A name formerly given to the paymaster's store-room in the after-part of the after-hold, reserved for stowage of spirits. The name applies at present to the paymaster's store-room for dry provisions.
Stanchions. Uprights placed under deck-beams to support them in the centre.
Starboard. The right side of a ship looking forward, as distinguished from port.
Steerage. The quarters of junior officers and clerks, situated outside the wardroom on either side of the deck, the space between the two steerage-rooms being known as the steerage-country.
Stem. The forward boundary of a ship, the continuation of the keel to the height of the deck.
Steps of Mast. Places into which the lower ends or heels of lower masts are secured or stepped. The fore and main masts are stepped at present in iron steps fitted over the main-keelson, with flanges to the sister-keelsons. The mizzen-mast step is a piece of timber secured to the orlop or berth deck beams.
Stern. The after-part of the ship.
Stern-post. The after-boundary of the ship, a continuation of the keel, tenoned
into the latter and secured to it in addition by composition plates.
Sweep-pieces. Ledges of wood hinged to the inner edges of gun-ports to give
additional facility in training the guns.
Taffrail. The rail around a ship's stern.
Tenon. The end of one piece of wood diminished and cut with shoulders to fit in a hole of another piece, called a mortise.
Thole-pin. Pins fitted in the gunwale of a boat, to be used with a rope ring or grommet as a rowlock.
Thwart. A cross-piece in a boat, used as a seat by the oarsmen.
Tiller. A bar of wood or iron which fits into the rudder-head and by which the steering is effected. (See Helm.)
Top. A platform at the eyes of the lower rigging, supported by the trestle-trees and cross-trees; the top-mast rigging sets up at each side of the top.
Top-gallant Forecastle. A deck raised over the forward end of the spar-deck extending from the bows nearly or quite to the fore-mast.
Top-rim. The forward edge of a top, rounded to prevent chafe.
Transom. A beam extending across the after-part of the ship.
Tree-nail. Pin of hard wood used as a fastening in the place of a metallic bolt.
Trestle-trees. Fore and aft pieces on each side of a mast resting on the hounds to support the rigging, cross-trees, etc.
Truck. A small wooden cap on a flag-staff or mast-head with holes or sheaves for halliards. A mast-head truck is also fitted to receive the spindle of the lightning-rod.
Ward-room. The quarters of the commissioned officers of a ship, usually occupying the after-part of the berth-deck. The rooms on the starboard side occupied by the line officers, those on the port side by the staff officers-the intervening space is styled the ward-room country.
Warping-chock. A block of wood, or metal casting, scored to receive a towline. Bridle-ports are fitted with such chocks, which can be removed when not in use.
Warrant-Officers' Rooms. Usually on the berth-deck, two on each side, forward of the steerage. The boatswain and gunner occupy the starboard, the carpenter and sail-maker the port rooms.
Waterways. Pieces of timber placed over the tops of the beams and secured to the beams and ship's side, filling the angle between the beams and the inside of the frame-timbers.
Wheel. A wheel to the axle of which are connected the tiller- or wheel-ropes by which the rudder is moved in steering.
Weigh. To weigh anything is to raise it-to weigh anchor.
Whiskers. Small spars projecting on either side of the bowsprit from the bees, extending the jib and flying-jib guys.
Wings of the Hold. That part of the hold or orlop which is nearest to the side.
Wythe. An iron fixture on the end of a mast or boom, bearing a ring through
which another mast or boom is rigged out. Pronounced with.
Yoke. A cross-piece of timber or metal fitted on the rudder-head when a tiller
cannot be used.
Spars and Rigging. The names of the spars and rigging of the ship are given in the references to Plate 2.
1. Fore royal stay.|
2. Flying jib stay.
3. Fore topgallant stay.
4. Jib stay.
5. Fore topmast stays.
6. Fore stays.
7. Fore tacks.
8. Flying martingale.
9. Martingale stay.
10. Jib guys.
11. Jumper guys.
12. Back ropes.
14. Flying jib boom.
15. Flying jib foot ropes.
16. Jib boom.
17. Jib foot ropes.
19. Fore royal truck.
20. Fore royal mast.
21. Fore royal lifts.
22. Fore royal yard.
23. Fore royal backstays.
24. Fore royal braces.
25. Fore topgallant mast and rigging.
26. Fore topgallant lifts.
27. Fore topgallant yard.
28. Fore topgallant backstays.
29. Fore topgallant braces.
30. Fore topmast and rigging.
31. Fore topsail lift.
32. Fore topsail yard.
33. Fore topsail foot ropes.
34. Fore topsail braces.
35. Fore yard.
36. Fore brace.
37. Fore lifts.
38. Fore gaff.
39. Fore trysail vangs.
40. Fore topmast studding sail booms.|
41. Foremast and rigging.
42. Fore topmast backstays.
43. Fore sheets.
44. Main truck and pennant.
45. Main royal mast and back-stay.
46. Main royal stay.
47. Main royal lifts.
48. Main royal yard.
49. Main royal braces.
50. Main topgallant mast and rigging.
51. Main topgallant lifts.
52. Main topgallant backstays.
53. Main topgallant yard.
54. Main topgallant stay.
55. Main topgallant braces.
56. Main topmast and rigging.
57. Topsail lifts.
53. Topsail yard.
59. Topsail foot ropes.
60. Topsail braces.
61. Topmast stays.
62. Main topgallant stunsail booms.
63. Main topmast backstay.
64. Main yard.
65. Main foot ropes.
66. Main mast and rigging.
67. Main lifts.
68. Main braces.
69. Main tacks.
70. Main sheets.
71. Main trysail gaff.
72. Main trysail vangs.
73. Main stays.
74. Mizzen royal truck.
75. Royal mast and rigging.
76. Royal stay.|
77. Royal lifts.
78. Royal yard.
79. Royal braces.
80. Mizzen topgallant mast and rigging.
81. Mizzen topgallant lifts.
82. Mizzen topgallant backstays.
83. Mizzen topgallant braces.
84. Mizzen topgallant yard.
85. Mizzen topgallant stay.
86. Mizzen topmast and rigging
87. Mizzen topmast stay.
88. Mizzen topsail lifts.
89. Mizzen topmast backstays.
90. Mizzen topsail braces.
91. Mizzen topsail yard.
92. Mizzen topsail foot ropes.
93. cross-jack yard.
94. cross-jack foot ropes.
95. cross-jack lifts.
96. cross-jack braces.
97. Mizzen mast and rigging.
98. Mizzen stay.
99. Spanker gaff.
100. Peak halliards.
101. Spanker vangs.
102. Spanker boom.
103. Spanker boom topping lift.
104. Jacob's or stern ladder.
105. Spanker sheet.
107. Port bow.
108. Port beam.
109. Water line.
110. Port quarter.
Sails. The names of the sails and certain running rigging of a ship are given in the following references to Plate 3.
NAMES OF SAILS.
1. Flying jib.
3. Fore topmast staysail.
4. Fore course or foresail.
5. Main course or mainsail.
6. Fore topsail.
7. Main topsail.
8. Mizzen topsail.
9. Fore topgallant sail.
10. Main topgallant sail.
11. Mizzen topgallant sail.
12. Fore royal.
13. Main royal.
14. Mizzen royal.
15. Fore trysail.
16. Main trysail.
18. Lower studdingsail.
19. Fore topmast studdingsail.|
20. Fore topgallant studdingsail.
21. Main topgallant studdingsail.
GEAR OF COURSES.
22. Clew Garnets.
25. Inner leechline.
26. Outer leechline.
28. Bowline bridles.
GEAR OF TOPSAILS, ETC.
30. Bowline and bridles.
31. Topgallant clewline.
32. Royal clewline.
33. Fore trysail vangs.|
34. Peak span.
35. Main trysail vangs.
36. Peak span.
37. Spanker vangs.
38. Throat brail.
39. Middle brail.
40. Foot brail.
41. Lower studdingsail outhaul
42. Lower studdingsail sheet.
43. Lower studdingsail clew-line.
44. Outer halliards.
45. Topmast studdingsail tack.
46. Topmast studdingsail downhaul.
47. T'gllt stuns'l tack.
48. Quarter boat.
49. Waist boat.
Rig of Vessels (compare Plate 4). Vessels are divided according to their rig into numerous classes, of which the following may be mentioned as the principal types usually met with at sea:
The Ship (1). Three masted, square rigged on all three masts.
The Barque or Bark (2). Three masted,
square rigged fore and main, fore and aft rig on mizzen.
The Barkentine (3). Three masted, square
rigged fore, fore and aft rig main and mizzen.
The Brig (5). Two masted, square rigged.
The Brigantine. Same as brig but without a square mainsail.
The Hermaphrodite Brig (6). Two masted,
square rigged fore, fore and aft rig main.
The Topsail Schooner (7). Two masted,
square rigged forward, but with a fore and aft foresail.
The Schooner. Two masted (8), three masted (4), or four masted fore and aft rig.
The Sloop (9). One masted, fore and aft rig.
NOTE. A vessel is said to be square rigged on a certain mast, when the sails set on that mast are bent to yards, and fore and aft rigged when the sails are bent to gaffs.
The topsail yards of merchantmen are almost invariably double, the topsail being in two parts, the lower part bent to the lower topsail yard and not hoisted, the upper portion bent to the upper yard and hoisted, as in the case of a single topsail. The clews, or lower corners, of the upper topsail are shackled to the yard arms of the lower topsail yard.
THE COMPASS.-THE LEAD.-THE LOG.
The Compass- A piece of steel which has been touched by a magnet, if free to move on a pivot, will point in a definite direction. To this direction, as a standard, all others may be referred, and any desired course thus followed.
The Mariner's Compass is based upon this principle. It consists of the needle, which is attached to the under side of a card, Fig. 1, representing the horizon, and graduated with the thirty-two "points" of the compass. The North end, or pole, of the needle is fixed under the North point of the card. The needle and card are balanced on a pivot fixed vertically in the compass-box, or bowl, and the whole is protected by a glass covering.
As the North mark of the compass-card always points with the needle to the North, the other marks will of course point to their respective parts of the horizon.
The variation of the compass and its local errors are not noticed here, as they may be referred to in any book on Navigation.
The Lubber's Point is a vertical line drawn on the inside of the bowl of the compass to correspond with the vessel's head; the point of the card coinciding with it shows the course steered, or the direction in which the ship is heading.
To Box the Compass is to name the points in regular succession, beginning at one point and ending at the same; thus, commencing with north and going around with the sun, say:-
North by East,
North-East by North;
North-East by East,
East by North,
East by South,
South-East by East,
South-East by South,
South by East,
South by West,
South-West by South,
South-West by West,
West by South,
West by North,
North-West by West,
North-West by North,
North by West,
Each point is further divided into half-points and quarter-points, and the fractional points are named upon the same principle as the points themselves; thus:-
N. 1/4 E.
N. 1/2 E.
N. 3/4 E.
N. by E.
N. by E. 1/4 E.
N. by E. 1/2 E.
N. by E. 3/4 E.
N. N. E.
N. N. E. 1/4 E.
N. N. E. 1/2 E.
N. N. E. 3/4 E.
N. E. by N.
N. E. 3/4 N.
N. E. 1/2 N.
N. E. 1/4 N.
N. E. 1/4 E.|
N. E. 1/2 E.
N. E. 3/4 E.
N. E. by E.
N. E. by E. 1/4 E.
N. E. by E. 1/2 E.
N. E. by E. 3/4 E.
E. N. E.
E. N. E. 1/4 E.
E. N. E. 1/2 E.
E. N. E. 3/4 E.
E. by N.
E. 3/4 N.
E. 1/2 N.
E. 1/4 N.
E., &c., &c.
A quarter-point (or half-point) can obviously be named with reference to either one of the nearest whole points. Thus N. 1/4 E. would be defined also as N. by E. 3/4 N., and E. N. E. 1/2 E. would be recognized as E. by N. 1/2 N.
The following are the usual rules for naming quarter-points:-
1st. From East or West to the nearest whole point, use for quarter-points that name which ends with the word North or South. Thus, E. 1/4 S., not E. by S. 3/4 E.
2d. From N. E., N. W., S. E., or S. W., to the nearest whole point use that name which ends with the nearest cardinal point. Thus, N. E. 1/2 N., not N. E. by N. 1/2 E.; N. W. 1/4 W., not N. W. by W. 3/4 N.
3d. In all other cases use that name of the quarter or half-point which ends with the word East or West. Thus, E. S. E. 1/2 E., not E. by S. 1/2 S.
A Dumb Compass is used at the mast-heads, taffrail, &c., for taking relative bearings. It consists of a compass-card painted on a board or cut on a copper plate.
Relative Bearings. In referring to the position of an object, the direction of the wind, &c., with reference to the ship, use is frequently made of what are called relative bearings, instead of giving the directions in compass-points.
In Fig. 2 a ship is represented as heading North. A lighthouse or other object if seen bearing North would also be said to bear, from that ship: Ahead.
If seen bearing N. by E.: One point on starboard bow.
Bearing N. N. E.: Two points on starboard bow.
Bearing N. E. by N.: Three points on starboard bow.
Bearing N. E.: Broad off starboard bow.
Bearing N. E. by E.: Three points forward of starboard beam.
Bearing E. N. E.: Two points forward of starboard beam.
Bearing E. by N.: One point forward of starboard beam.
Bearing East: Abeam.
Bearing E. by S. One point abaft starboard beam.
Bearing E. S. E.: Two points abaft starboard beam.
Bearing S. E. by E.: Three points abaft starboard beam.
Bearing S. E.: Broad off starboard quarter.
Bearing S. E, by S.: Three points on starboard quarter.
Bearing S. S. E.: Two points on starboard quarter.
Bearing S. by E.: One point on starboard quarter.
Bearing South: Astern.
And similarly at N. by W., N. N. W. &c., one point on port bow, two points on port bow, &c., &c.
To find the direction of the wind, when ship is close hauled.-A square-rigged ship, when close hauled, can usually lie no nearer the wind than six points; therefore, if a ship be close hauled on the starboard tack, and her head at North, count six points thence to the right hand, or towards East, and you will find the wind at E. N.E. The wind then forms with the keel an angle of six points, so that if a line at Fig. 2, Plate 6, represents the ship's keel, (c) will be the yard when braced up, and (d) the direction of the wind. In practice the yard is braced up sharper, to make the sail stand to better advantage.
When the ship is on the port tack with her head North, the points are counted on the opposite or left side, and the wind is W. N.W. If the ship's head be put to any point of the compass, counting six points to the right or left hand, according. as the ship is on the starboard or port tack, will always give the direction of the wind when the vessel is close hauled.
When the wind is E. by N., in Fig. 2, the ship is then one point free, because her head is seven points from the wind. With the wind East in the figure, it is said to be two points free, or abeam, as shown in the remarks on relative bearings. If the wind is at S. in the figure, it is said to be aft.
After learning to box the compass with the sun, go around against the sun, or from North towards West, and practise with such questions as the following: Ship on the port tack, heading S. W. 3/4 W., how will she head on the other tack? With the wind at S.W. and steering due East,
the ship is hauled up, two points and a half, how will she head? Close hauled, with the port tacks aboard, heading S. S.E., you bear up, keeping away six points, how will the ship head, and how will the wind be with reference to the ship's beam? Ship heading N. N.E. on the starboard tack, a lighthouse is reported from aloft bearing two points abaft the lee beam, how will it bear by compass, &c., &c.?
Soundings, to ascertain the depth of water on entering or leaving a port, or in any case where there is supposed to be less than twenty fathoms of water, are taken by the hand lead, Fig. 3, a quartermaster or forecastle-man being stationed in the main chains for the purpose; the lead weighing, from seven to fourteen pounds, and the line being from twenty. to thirty fathoms in length. Hand lead lines are marked as follows:
At 2 fathoms from the lead, with 2 strips of leather.
At 3 fathoms from the lead, with 3 strips of leather.
At 5 fathoms from the lead, with a white rag.
At 7 fathoms from the lead, with a red rag.
At 10 fathoms from the lead, with leather, having a hole in it.
At 13 fathoms from the lead, as at 3.
At 15 fathoms from the lead, as at 5.
At 17 fathoms from the lead, as at 7.
At 20 fathoms from the lead, with 2 knots.
At 25 fathoms from the lead, with one knot.
At 30 fathoms from the lead, with three knots.
At 35 fathoms from the lead, with one knot.
At 40 fathoms from the lead, with four knots. And so on.
These are known as the "marks." The numbers omitted, as 1, 4, 6, 8, &c., are called the "deeps," and they are spoken of together as the "marks and deeps of the lead line."
All lead lines should be marked when wet.
Soundings by the hand-lead are taken while the vessel has headway on, the leadsman throwing the lead forward, and getting the depth as the vessel passes, while the line is nearly perpendicular. He communicates to the officer the soundings obtained, thus:
If the depth corresponds with either of the above marks, he says, "By the mark 5 or 7. If the mark is a little below the surface, he says, "Mark under water 5 or 7." If the depth is greater, or one half more than any of the marks, he says, "And a quarter," or "And a half 5 or 7." If the depth is a quarter less, he says, "Quarter less 5 or 7." If he judges by the distance between any two of the marks
that the depth of water is 4, 6, 8, 9, 11, 12, 14, 16, 18, 19, or 21 fathoms, he says, "By the deep 4," &c.
On the hand-lead line there are nine "marks" and eleven "deeps."
Require the soundings to be given in a sharp, clear and decided tone of voice. In steamers, this is certainly the best plan, for while the old-fashioned "song" is being drawled out, the vessel may run ashore.
The Breast-band or Rope, generally the
former, made of canvas, secured at both ends to the rigging, supports the body of the leadsman while heaving the hand-lead.
Besides the breast-band, it is a very good plan to have fitted, in connection with it, a tarpaulin apron, to cover the "leadsman" from the feet to the waist. This keeps him dry and adds much to his comfort.
On going into the chains for the purpose of sounding, the leadsman should see the breast-rope properly secured; his line clear, and the end made fast. If at night, he should take the distance from the breast-rope to the water's edge; then at each cast deduct this distance from the mark at hand and give it as the true sounding.
The Coasting Lead is used in depths from 25 to 100 fathoms, the lead weighing from 25 to 50 pounds.
The Deep-sea Lead is used in depths of over 100 fathoms, and weighs from 80 to 150 pounds.
Both coasting and deep-sea (pronounced "dipsey") leads are hollowed out at the base to receive an arming of tallow. When the lead strikes, the tallow becomes coated with sand, pebbles, shells or other substances which show the character of the bottom. This information, compared with the description of the sea bottom given on the chart, may prove of value in determining the ship's position. Instead of being hollowed out at the bottom, the deep-sea lead may have a specimen cup, of brass, at the end, as shown in Fig. 4. The coasting and deep-sea lines are marked alike as follows:
10 fathoms, one knot.
20 fathoms, two knots.
30 fathoms, 3 knots, &c., &c., and at every intermediate five fathoms by small strands. At 100 fathoms the line is marked with a piece of red bunting.
To Sound with the Deep-sea Lead. The men are ranged outside the vessel from the weather mizzen chains to the cathead. The line is passed forward outside and clear of everything. The lead is sent forward on deck, and the line bent to it by the captain of the forecastle. The line is then hauled forward, each man collecting a coil of several fathoms in his hand, commencing forward, until the officer thinks there is line enough out. It is then snatched in a small snatch-block, Fig. 5, secured to the
after mizzen rigging, or to the weather spanker yang, the remaining part of it being coiled down in a tub or rack, or wound on a reel, clear for running. Everything being in readiness, and the vessel's headway sufficiently deadened, the officer orders, Stand by! Heave! The captain of the forecastle heaves the lead as far forward as he can, and at the same time cries, Watch-ho! Watch! And each man, as the line runs out from his hand, holds it clear of the side, and repeats the cry, Watch-ho! Watch! In the mean while, the line runs out until the lead touches the bottom, or until a sufficient quantity has been run out to satisfy the officer that no bottom has been found. The men then lay aft and man the line! and walk forward with it; a petty officer being stationed by it, to note the depth of water by the first mark that comes in.
If bottom has been found, it will instantly be known by the line bringing up suddenly in running out, or by the arming on the lead after it is hauled up; by which the nature of the bottom is known.
To get sounding by the deep-sea lead while lying to in a gale, or in any case when the vessel drifts much to leeward, it is proper to pass the line from to windward around the stern, and then forward on the lee side, and to heave the lead from to leeward, which will bring the line nearly perpendicular by the time the lead touches the bottom.
In heaving the deep-sea lead, the men stationed in the chains should be cautioned not to let the line go until they feel the lead take it, for if the ship is in much shoaler water than was anticipated, it is thus detected at once.
Besides the common lead, there are a variety of "patents" for sounding; the one known as Massey's lead, being about the most successful. In this, a machine is attached to the lead, and a fan set in motion by its descent. The motion is communicated to a register wheel, and the number of fathoms corresponding to the depth of water is pointed out by an indicator. This lead should also have a good arming of tallow to bring up specimens of the bottom.
The Drift Lead. While at single anchor, it is proper always to have a lead somewhat heavier than the hand-lead, say from fourteen to twenty pounds, over the side, and resting on the bottom, with a man to attend it. Of course, this is only necessary in a stiff breeze, or at night. But in a vessel-of-war, it should be observed as a standing rule, without regard to the weather. By this you will have instant notice if the vessel parts her cable or drags her anchor.
Various methods have been proposed for measuring the rate at which a ship sails; but that most in use is by the Log and Glass.
The Log is a flat piece of thin board, of a sectoral or quandrantal form, Figs. 6a and b, Plate 5, loaded, on the circular side, with lead sufficient to make it swim upright in the water. To this is fastened a line, about 150 fathoms long, called the log-line, which is divided into certain spaces called knots, and is wound on a reel, Fig. 7, which turns very easily. The Glass is of the same form as an Hour-Glass, Fig. 8, and containing such a quantity of sand as will run through the hole in its neck in twenty-eight seconds.
Marking the Log-Line. Previous to marking a new Log-line, it is soaked in water for a few days, in order to get it in the condition it will be when in use. From fifteen to twenty fathoms is allowed for "stray-line;" and then the length of a knot determined (for the 28-second glass) by the following proportion, viz.: As the number of seconds in an hour is to the number of feet in a sea mile, so is the length of the glass to the length of a knot, or,
3,600 s : 6,086 ft. = 28 s||: 47.33 ft.|
| ||: 47 feet 4 inches;
therefore the length of the knot is 47 feet 4 inches for the 28-second glass.
The velocity of the ship is estimated in knots and tenths of a knot.
The limit of "stray-line" is marked by a piece of red bunting about six inches long, and each length of 47 feet 4 inches after that by a piece of fish-line with one, two, three, etc., knots in it, according to, its number from the "stray-line."
Each length of 47 feet 4 inches (the "knot") is subdivided into five equal parts, and a small piece of white bunting about two inches long is turned into the line at every two-tenth division thus formed.
Always, before leaving port, the Navigator has the line thoroughly soaked for a few days, and then all the marks placed at their proper distances. He also compares all the sand-glasses with a watch, and if any should be incorrect, he makes them run the proper time by taking out or putting in sand, as the case requires. During daylight, especially in very damp weather, it is preferable to use a watch to a sand-glass for noting the time. Errors of the glass due to moisture are commonly corrected by drying it at the galley.
Heaving the Log.-To find the ship's speed is
called heaving the log, and is thus performed: One man holds the reel, and another the glass; an officer of the watch throws the log over the ship's stern, on the lee side, and when he observes the stray line is run off (allowed to carry the log out of the eddy of the ship's wake), and the red rag is gone off, he cries, Turn; the glass-holder answers, Turn; and watching the glass, the moment it is run out, says, Up. The reel being immediately stopped, the last mark run off shows the number of knots, and the distance of that mark from the rail is estimated in tenths. Then the knots and tenths together show the distance the ship has run the preceding hour, if the wind has been constant. But if the wind has not been the same during the whole hour, or interval of time between heaving the log, or if there has been more sail set or handed, a proper allowance must be made. Sometimes, when the ship is before the wind, and a great sea setting after her, it will bring home the log. In such cases, it is customary to allow one mile in ten, and less in proportion if the sea be not so great. Allowance ought also to be made, if there be a head sea.
This practice of measuring a ship's rate of sailing, is founded upon the following principle, that the length of each knot is the same part of a. sea mile;* as twenty-eight seconds is of an hour.
In heaving the log, you must be careful to veer out the line as fast as the chip will take it; for if it be left to turn the reel itself, it will come home and deceive you in your reckoning. You must also be careful to measure the log-line pretty often, lest it stretch and deceive you in the distance. Like regard must be had that the glass be just 28 seconds; otherwise no accurate account of the ship's way can be kept. The glass is much influenced by the weather, running slower in damp weather than in dry. The glass may be examined by a watch, as above stated, or by the following method:-Fasten a plummet on a line, and hang it on a nail, observing that the distance between the nail and middle of the plummet be 39 1/8 inches; then swing the plummet, and notice how often it swings while the glass is running out, and that will be the number of seconds measured by the glass.
If the vessel's speed is greater than four knots the fourteen-second glass is used instead of the twenty-eight second, and the number of knots run out is doubled to ascertain the actual rate of sailing, as the line is graduated for the twenty-eight second glass. The twenty-eight and fourteen second glasses are called respectively the long and short glasses.
* A statute mile is 5,280 feet. To convert sea miles into statute miles, multiply the former by 1.153. To convert statute miles into sea miles, multiply by the decimal .868.
The Patent Log is now in constant use, especially on board steamers. It should be rigged out by a spar, so as to clear the wake, and care taken to haul it in whenever the ship is stopped.
Massey's Patent Log is composed of a brass wedge-shaped box, having within three cogged wheels, acting on each other in such proportion that a total revolution of one completes a division of the next (or one-twentieth), a revolution of the next, one-eighth, registering thus from one hundred and sixty miles to tenths, and decimal parts; the action is by the rotation of a spindle with four spirally-fixed wings (termed the rotation, or fly), which turns an endless screw in the box, acting directly on the decimal wheel. It is towed astern by a stout lead line of sixty fathoms, and is registered every time the course is changed, angles taken, &c., but should not be reset until the twenty-four hours have elapsed, or the ship anchors, or goes less than three knots-when it becomes uncertain from not towing horizontally.
When great accuracy is required it is well to use two logs, putting one overboard as the other is hauled up, as when the course is changed, etc.
The Taffrail Log, Fig. 9. This is a mechanical log of the same character as Massey's, but it has the advantage of towing only the fly, the registering apparatus being at the inboard end of the trailing line so that it can be easily read without hauling in the line. In one patent of this kind there is placed between the register and fly a conical hollow metal piece upon which the vibrations due to pitching are taken.
Registering logs are frequently made to strike a bell at every mile or five miles of the run.
Among the various speed indicators which, like the common log, are useful in showing changes of speed, the instrument invented by Ensign Hogg, U. S. Navy, has given very satisfactory results, and may be described as follows:
Fig. 10 shows a sailing vessel with the vacuum instrument represented in Fig. 11, towed astern by a hollow gum tube, the length of which for the largest vessels is 75 feet. The tube is supported in the water at low speeds by the buoy in Fig. 12. The mercurial gauge, Fig. 13, is on board the vessel; at present a metallic gauge is generally substituted.
The action of the speed indicator is as follows: The water rushing through the instrument at A, Fig. 11, causes a vacuum at the small end of the mouth-piece B. This vacuum communicates by means of the gum-tube with the vacuum-gauge on deck, and the greater the vacuum, the greater the speed. The graduations on the vacuum-gauge are found by experiment.
The only difference with a steamer is that the rubber tube is rigged out about three feet by an outrigger from the ship's side, and the vacuum instrument is towed alongside.
The Ground Log is the common log line with a hand-lead attached, and is used in tideways and currents, in soundings, to ascertain the vessel's speed over the ground.