North Coast of France Pilot, Including the Channel Islands

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Hydrographic Office under the authority of the Secretary of the Navy, 1915 - 633 Seiten
 

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Seite 27 - For boarding a wreck, it is recommended to pour oil overboard to windward of her before going alongside. The effect in this case must greatly depend upon the set of the current and the circumstances of the depth of water.
Seite 17 - A knowledge of them is useful in order that they may be taken advantage of or avoided. A swift current often occurs in a narrow passage connecting two large bodies of water, owing to their considerable difference of level at the same instant. The several passages between Vineyard Sound and Buzzards Bay are cases in point.
Seite 12 - For vessels drawing less than 18 feet the edge of the sanding serves as a well-marked danger line. Charts on which no fathom curves are marked must especially be regarded with caution, as indicating that soundings were too scanty and the bottom too uneven to enable the curves to be drawn with accuracy. Isolated soundings, shoaler than surrounding depths, should always be avoided, especially if ringed around, as it is doubtful how closely the spot may have been examined and whether the least depth...
Seite 25 - The gradual change in the variation must not be forgotten in laying down positions by bearing on charts. The magnetic compasses placed on the charts for the purpose of facilitating plotting become in time slightly in error, and in some cases, such as with small scales, or when the lines are long, the displacement of position from neglect of this change may be of importance. The compasses are...
Seite 16 - Low water is lower than mean low water about half the time, and when a new or full moon occurs at perigee the low water is lower than the average low water of springs. At the equinoxes the spring range is also increased on the coasts of Europe, but in some other parts of the world, and especially in the Tropics, such periodic low tides may coincide more frequently with the solstices. Wind or a high barometer may at times cause the water to fall below even a very low plane of reference. On coasts...
Seite 18 - The three-arm protractor or station pointer consists of a graduated brass circle with one fixed and two movable radial arms, the three beveled edges of the arms, if produced, intersecting at the exact center of the instrument. The edge of the fixed arm marks the zero of the graduation which enables the movable arms to be set at any angles with the fixed arm. To plot a position, the two angles observed between the three selected objects are set on the instrument, which is then moved over the chart...
Seite 19 - In all such cases angles should be taken to several objects, the more the better; but five objects is a good number, as the four angles thus obtained not only prevent any errors, but they at once furnish a means of checking the accuracy of the chart itself.
Seite 14 - The intrinsic power of a light should always be considered when expecting to make it in thick weather. A weak light is easily obscured by haze, and no dependence can be placed on its being seen.
Seite 26 - Use of Oil for Modifying the Effect of Breaking Waves. — Many experiences of late years have shown that the utility of oil for this purpose is undoubted, and the application simple. The following may serve for the guidance of seamen, whose attention is called to the fact that a very small quantity of oil...
Seite 53 - ... ready for use, and shall flash or show them at short intervals to indicate the direction in which they are heading; but the green light shall not be shown on the port side nor the red light on the starboard side.

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