3J2 KirilOLLS's SEAMANSHIP AND NAUTICAL KNOWLEDGE
•motion through the water as if she was being towed at the rate of 3
or 4. knots in still water It is sometimes helpful to look at the
subject in this light, and to regard the anchor as towaig the ship through
the water.
Effect of the tide,—The effect of the tide is least when the ship
is stem on to it, and increases as she comes athwart, being greatest when
broadside on. The strain on the cable is, therefore, least when the ship
is stem on to the tide with the anchor right ahead To keep her thus,
however, would necessitate steering her as if under way, and under
ordinary circumstances where there is no likelihood of dragging, this is
not necessary or convenient because if left to herself with the helrr* amid-
ships she would yaw about; it is best to give her a sheer to one side of
her anchor with the helm, so that with the helm and cable together the
ship will be kept fairly steady.
When, however, the tide is strong and holding ground bad, and there
is any risk of dragging the anchor, only very little sheer should be given,
as the more sheer a vessel is given the greater is the tension put on the
cable. Under these conditions, therefore, in order that the ship may
be kept as steady as possible, it may be advisable to steer the ship as il
under way.
"When a vessel is sheered to one side of the anchor, and the tide
coming on the wrong bow shoots her across to the other side of her anchor
she is said to "break her sheer." It must be borne in mind that it is not
a steady continuous strain which is most likely to start the anchor, but
the easing up and * sudden tightening, such as would occur if a vessel
broke her sheer, or if she is rising and falling in a heavy swell or sea.
Wind and tide.—The effect of strong winds on a vessel at anchor
may be considerable, especially if she is light. If the wind and tide are
ahead the effect of the two will be combined, and if there is a risk of
driving the precautions already stated should be taken:
When the wind and tide are in opposite directions the ship is affected
by the difference of the forces, and by judicious management the strain
apon the cable may be considerably reduced. Suppose the ship to be
tide rode with the wind aft; the effect of the wind will be to ease the
strain upon the cable. Imagine now that the wind increases until
it has a greater effect than the tide; the ship then begins to forge ahead
towards her anchor. She must be steered clear of the anchor until
she is ahead of it, when the cable will bring her up again. Be careful
to keep her head on to the tide by meeting her with the helm, as though
the wind may be strong enough to drive her up against the tide whefc