212

NICHOLAS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE

that if you see a side-light of another vessel ahead, the positions are
reversed, and the other vessel is in the act of crossing. Unless the
vessels are near each other, there is very little risk of collision in these
two cases, but care should be taken in the vessel having the other ahead
not to deviate from her course towards the direction in which the other
vessel is heading.

Again, if the bearing of a light does not change appreciably, it not
only shows that risk of collision exists, but it also gives a hint as to
the probable direction in which the other vessel is heading. It may be
stated as a general rule that the broader a light bears on the bow th

c.

A,

. a.

farther away must be the point of collision. Suppose you see, about
a point on the bow, the side-light of another vessel crossing, and let
us assume, for the purpose of illustration, that both vessels are going 10
miles an hour, that they are 2 miles apart, and are proceeding in such
lirections as to involve risk of collision. The point of collision would
be about 1 mile away, and would be reached (assuming that each
vessel kept her course and speed) in about 6 minutes. Had the light
jeen about 4: points on the bow, the collision point would have been
Jxmt 1^ miles away, and would have bften reached in about 9 minutes.