head lights are seen, the situation should be perfectly clear by the time the side-lights are made out, and if danger of collision has been found to exist, a (the "giving way" ship) should be ready to act at once. She may give way by changing speed, or course, or both, but it is always simpler to change the course than to reduce the speed materially; and this has the further advantage that it gives notice to в of what has been done-provided the course can be changed sufficiently to open the red light. It will not usually be necessary to make so great a change as this, merely to insure passing astern, but it is very desirable to do it if в is not too far on the bow, as it immediately clears up the situation for both ships. The whistle signal required by the Rules of the Road, for a change of course, is an additional safeguard in this case, which could not be used for a mere reduction of speed. If, however, в is more than three or four points on the bow, it will suffice to slow as much as may be necessary to let her draw ahead, changing course later if it shall seem advisable.

In changing course to avoid collision, right rudder1 is required of A by the article which directs her, whenever possible, to pass astern of B. This is a survival of the old "Law of Port Helm” which has been the object of such violent denunciation from writers on the Rules of the Road. When confined, as it is by the present rules, to the ship having the other on her own starboard hand, this law is perfectly sound; but it was at one time regarded as applying to all ships under almost all circumstances.

2nd, If the vessels are dangerously close when they sight each other, A is relieved from the obligation to pass astern of B, unless it shall appear that this is the safest course that she can take. We shall find that, as a matter of fact, it is in a majority of cases the only course that can give her a hope of safety; and that right rudder1 is usually even more imperatively demanded of her in this case, than when the space available for manoeuvring is greater.

The first impulse of many officers in such a situation is to turn away from the danger, and at the same time to reverse the engines with full power. This course is much more likely to cause collisions than to prevent them. It may be right for в (the holding-on vessel) to turn away, if the emergency is such as to call for any action on her part; but if she does this, so far from reversing her engines, she should, if possible, increase her speed, as

1 Port helm.

her whole effort must be directed to getting across the bow of a as quickly as possible. On the other hand, A should reduce her speed, but should at the same time turn to starboard.

A vessel turning away from another vessel to avoid collision should always continue at full speed, as the effort involved in this course is an attempt to cross the other vessel's bow. To turn away and slow is the surest possible way of bringing about collision.

To make it clear why A turns toward the danger instead of away from it, we may refer to Plates 131 and 132, where в is placed, in the successive figures, on bearings from two to five points on A's bow, and showing a red light. In such a situation, the action to be taken will not depend upon the exact distance between the ships. This distance is here taken, for convenience of plotting, at 500 yards, but it may be more or less than this without modifying the principle involved, except in one special case to be hereafter considered.

As we cannot suppose that A in this case has time to watch for a change of bearing, or that she will have any information of B's course and speed beyond that given by a red and white light, we must consider that, so far as A's knowledge goes, в may be heading anywhere between the lines BX and BY. If, however, she is heading nearly along BX, she is safe to pass astern of A;' and if she is heading well off toward By, the danger of collision, although it may still exist, will be comparatively remote. The situation will not be one of serious emergency unless в is heading on some course within the sector SBT.

If A turns to starboard and reverses, using helm and engines together to the best advantage, she will follow the heavy line (approximately). If she has twin screws and reverses the inner one, at the same time putting her helm aport, she will follow the light line. In either case, if she does not turn clear of the danger sector, she will cut only a few of its lines (that is to say, only a few of the possible courses of B); and she will at the same time present her stem to B, thus reducing, at once, the danger of collision and the damage to be expected if collision occurs. If she

'It will be noted that A could, by turning with the starboard screw backing, collide with в even if в is heading along BX; but long before this could happen, A would see B's green light and would resume her

course.

turns to port, she not only cuts every one of the courses of B within the danger sector, but she throws herself across B's path broadside on, inviting the most fatal blow that one ship can give another.

If it be contended that, in placing the ships 500 yards apart, we have taken too great a distance for urgent danger, the answer is that at less than this we approach the case in which collision is not only imminent but almost inevitable and for which no hard and fast rules can be laid down. Whether, in such a case, it is safer to turn toward the danger or away froro it will depend largely upon the angle at which the courses converge, and when the vessels are very close together, we may assume that something will be known about this, since it is hardly to be supposed that two vessels within a few hundred yards of each other will not see something besides each others running lights. If it is seen that the courses converge as in Fig. 3, Plate 132, the ships being very close together, it is clear that each should turn away from the other, and stop. If A has twin-screws she would back the port screw full speed. If she has a single right-handed screw, it may be dangerous to back if B is very close.

In the case where A has в nearly on the beam, the importance of turning inward is less marked than when she is on the bow, and it is generally safe to slow or stop to let her draw ahead, or at least to let the situation declare itself clearly.

With regard to B's course when she finds herself called upon under Art. 21 to act for the avoidance of collision with a vessel on her port hand (A), she should, in most cases, turn away, with right rudder,1 and keep her speed or if possible increase it. But this involves presenting her broadside to A; and if the ships are so close that it is evident collision cannot be avoided, there is no question that B should turn inward, presenting her bow as nearly as possible to A, and stopping; remembering, if she has a single (right-handed) screw, that backing will throw her head to starboard and may defeat the object of the manœuvre. This is a situation for which it is impossible to lay down hard and fast rules; and all that is attempted here is to call attention to all the factors in the problem.

If B has twin screws, she should, if she puts her rudder to

1 Port helm.