Practical Information on the Deviation of the Compass: For the Use of Masters and Mates of Iron Ships ..

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H.M. Stationary Office, 1863 - Compass - 122 pages
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Page 13 - Kronstat to enable mariners to determine the deviations of their compasses, as resulting from the effects of the iron of the ship, or the 'cargo on board, whilst lying at anchor in the great roadstead of that port : viz. : — The correct magnetic bearings of the foundry chimney from various parts of the western wall of the commercial port of Kronstat are indicated by a series of marks, ranging between the bearings of N. 89 E. and S. 79 E., painted on the western face of the wall. The degrees...
Page 35 - ... upon so long as she remains upright. Besides the ordinary deviation of the compass there is a deviation caused by the heeling of iron ships, which may increase or decrease the deviation observed when the ship is upright. Cases have been observed in which the deviation from heeling has amounted to as much as two degrees for each degree of heel of the ship, that is, without altering the real direction of the ship's head, the apparent alteration in direction has amounted to 40 by heeling the ship...
Page 56 - ... bad steering. In one case, in a screw steamer in active employment, the pivot had not even been examined for about eight months ; in another screw steamer the pivot had not been changed or sharpened for nearly twelve months ; and in a third case the agate cup in which the pivot rested had been filled up with brickdust, for the purpose, it was stated, of steadying the card, so that when examined it was found that the vibration from the screw and the grinding of the brickdust had made a hole completely...
Page 56 - ... most valuable results would certainly be obtained. It may be added that the observations so made would furnish a test of the care, skill, and good faith of the captain who made the observations, as the process of reduction shows almost infallibly the genuineness and correctness of the observations." Undoubtedly the best practical corrective for errors of the compass of all kinds is to be found in a competent and careful captain. How to make the captains and future officers of iron ships more...
Page 13 - J. Belavenetz, of the Russian Imperial Navy, has made the following arrangement in the commercial port of Kronstat to enable mariners to determine the deviations of their compasses, as resulting from the effects of the iron of the ship, or the cargo on board, whilst lying at anchor in the great roadstead of that port : viz. — The true bearings of the foundry chimney from various parts of the western wall of the commercial port of Kronstat are indicated by a series of marks, ranging between the...
Page 10 - Committee: — 1. Quadrantal deviation may be large in amount in a small ship, and small in a large ship, and the reverse ; 2. Generally it is larger in amount in the middle of a large ship than in positions nearer to the ends ; 3. It decreases rapidly as the compass is raised above the deck, and at a certain height above it may change from plus to minus ; 4. In the usual positions...
Page 10 - ... may be large in amount in a small ship, and small in a large ship, and the reverse. 2. Generally, it is larger in amount in the middle of a large ship than in positions nearer to the ends. 3. It decreases rapidly as the compass is raised above the deck, and at a certain height above, it may change from plus to minus. 4. In the usual positions for a compass the quadrantal deviation is almost invariably plus, but it may be minus in a compass placed over a hatchway or skylight, or on the bridge...
Page 27 - To determine the deviation due to D for any given point, with this co-efficient reduced to tenths of a degree, enter the table as before described, but at top or bottom with twice the number of points that the ship's head is from either of the cardinal points, and the departure will give the number of tenths of a degree due to D. This will have the same sign as the coefficient in the quadrants from north to east, and from south to west, but a contrary sign from east to south and from west to north....
Page 56 - ... the mode of properly applying a compensating magnet whenever it may be required at sea. But not unfrequently the reported compass errors of iron ships arise from purely mechanical causes, which have no connexion with the ship's magnetism. They are sometimes due to cracked or holed agates, but more commonly to worn pivots, with needles which have never had or have lost their proper directive power. An opinion prevails with some compass makers that the steel pivot for the card should not be hardened,...
Page 56 - ... found in a competent and careful captain. How to make the captains and future officers of iron ships more competent in this special department of their very varied duties deserves the most careful attention. A fair knowledge of the elements of magnetism and mechanics may, it is thought, be reasonably required in the commander of an iron ship. The practical mode of correcting the compass is so simple, and may be acquired in so short a space of time, that every officer in an iron ship might be...

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