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were on the bridge. One man was on the look-out from the starboard side of the bridge. His ordinary place was on the forecastle-head, but he was not placed there that night, as there was a heavy head sea, and the vessel was shipping water. His attention was called to a light by the look-out man. It was almost ahead about a mile and a half off. He could not at first distinguish whether it was red or green, as it was dim; but when he made it out to be a green light it bore two to three points on the port bow, and it was only three or four lengths off. He heard no order given to the man at the wheel when the light was first reported; but when witness found that it was a green light he ordered the helm hard aport. If the steamer had starboarded at this time she would have gone right over the yacht. The • Owl' had been going at the rate of six or seven knots; but when she collided there was no way on her, the engines having been reversed. After tho yacht went down the captain ordered a boat to be got out, but subsequently countermanded the order, on the ground that more lives would be lost, as it was not fit to go out. At the close of his examination the witness stated that he would not have gone out in a boat on such a night as that, even if the captain had ordered him-a remark which appeared to greatly astonish the nautical assessors."
He ported his helm to bring his ship round to starboard, but he also reversed his screw; and as he says nothing about having again starboarded his helm, it would appear that from the time of reversing the screw until the collision (time enough to stop the ship), she had moved straight forward or inclined to port. Had he not reversed his screw, but kept on full speed, it is clear the collision could not have happened, for at the time the collision did happen his ship would have been more than her own length away from the spot where the collision occurred. He admitted himself that to have starboarded his helm must have brought about the collision, so he ported his helm and reversed his screw, which, as it had the same effoct, did bring about the collision.
From the Committee's report just read, it appears that a ship will turn faster, and for an angle of 30°, in less room when driving full speed ahead, than with her engines reversed, even if the rudder is rightly used. Thus when an obstacle is too near to admit of stopping the ship, then, as was done in the case of the • Ohio,' mentioned in my paper last year, the only chance is to keep the engines on full speed ahead, and so to give the rudder an opportunity of doing its work.
These general laws are of the greatest importance, but they apply in different degrees to different ships; and each commander should determine for himself how his ship will behave. A ship’s ordinary steering-power may soon be learnt in general use, but not so the effect of stopping ; there is thought to be a certain risk in suddenly reversing the engines, which any one in charge of a ship will shrink from, unless he knows it is recognized as part of his duty.
It is also highly important that the effect of the reversal of the screw should be generally recognized, particularly in the law courts; for in tho present state of opinion on the subject, there can be no doubt that judgment would go against any commander who had steamed on ahead, knowing that by so doing he had the best chance of avoiding a collision, or who had ported his helm in order to bring his ship’s head round to port, with the screw reversed. It seems to me, therefore, that it would be well if steps could be taken by this Association to bring the matter prominently before the Admiralty, the Board of Trade, and those concerned in navigation.
So far as the capabilities of each individual ship are concerned, there is no insuperable difficulty or risk about the experiments, and to have determined these will be a great point. When the officers know exactly what can be done in the way of turning their ships, and how to do it, the chances of accidents must be greatly reduced.
But at all events for fighting ships it is desirable that the officers should have experience beyond the mere turning powers of their own ships. When two ships are mancuyring so as to avoid or bring about a collision, each commander has to take into account the movements of his opponent. To enable him to do this with readiness, it would be necessary to have friendly encounters. A fight between two ships whose captains had never before fought, would be like a tournament between two novice knights who had never practiced with pointless spears; and such a contest, although not unequal, must be decided by chance rather than skill.
Unfortunately sham fights or tournaments between ships with blunt rams would be about as dangerous as a real fight; and the chance of an accident would be far too great for such friendly tournament, however important, ever to become an essential part of the training of a naval officer, as they were of the knights of old. For although, should war arise, the danger from want of experience may be even greater than the danger of an accident in gaining such experience by friendly fights, yet, as the chance of war is always remote, the former risk would be preferred; and this is not all.
As yet there has been no such thing as a ramming fight between steamships ; so that not only are our officers without actual experience, but even the rules by which they are instructed to act (the rules of naval tactics) are based entirely on theoretical considerations, and hence are very imperfect.
Now there appears to me to be a means by which experience of the counter-maneuvring powers of ships, as well as the manœuvring powers of single ships, could be ascertained without any of the risk and but little of the cost attending on the trials of large ships, and which, if not equal to an actual fight, would be very useful as a means of training the officers.
If small steam-launches were constructed similar to the ships, so that they represented these ships on a given scale (say one tenth linear measure), and their engines were so adjusted that they could only steam at what we may call the speed corresponding to that of the larger ships, then two launches would maneuvre in an exactly similar manner to the large ships, turning in one tenth the room ; and the time which the manœuvres with the launches would take would only be about half that occupied by similar manoeuvres with full-sized ships. The only points in which it would be necessary that the model should represent the ship would be in its shape under water and as regards the longitudinal disposition of its weights. The centre of gravity should occupy the same position amidships, and the longitudinal radius of gyration of the model should bear the same proportion to that of the ship as the other linear dimensions. In other respects the model might be made as was most convenient. It might be made of wood, and so strengthened that two models might run into each other with impunity.
There would not be much difficulty in so strengthening the models, as the speed of the models would be very small. For instance, if the speed of the ship were 134 knots, then that of the model would be 41 knots.
The study of the qualities of ships from experiments on their models has not until recent years led to any important results. But this in great part was owing to the fact that proper account had not been taken of the effect of the wave caused by the ship and the consequent resistance. It was not
Report Brit. Assoc. 1876.
Diagrams for Report of B.A. Committee on Steering.
This shows approximately the effect of reversing the screw
This shows approximately the effet of reversing the screw
known that the waves set up by the model bear the same relation to the size of the model as the waves set up by the ship do to the ship when, and only when, the speed of the model is to the speed of the ship in the ratio of the square root of the ratio of their lengths.
Since this fact has been recognized, most important information has been obtained by experimenting on models. Mr. Froude, by recognizing this law, has been able to bring the comparison of ships by means of their models to such a degree of perfection, that he can now predict with certainty the comparative and actual resistance of ships before they are constructed, and the great practical value of his results have been recognized by the Admiralty.
What I propose is virtually to extend these experiments on models so as to make them embrace the steering-powers of ships as well as their resistances. The manner of experimenting would have to be somewhat altered. Steam-launches would have to be substituted for dummy models; but the principle of the experiments would have to remain the same, and the speed of the launches must be regulated by the same law as that of the models. · The turning qualities of such launches might be verified by comparing them with the turning qualities of the ships as found by actual experiment; and then the models might be handed over to the officers of the ships, and they might practice encounters and maneuvres until they knew not only what they could do with their ships, but what it was best to do in order to outmanæuvre each other, and this without any cost or risk.
The behaviour of the models would be in all respects similar to that of the ships, the only difference being that the manœuvres would be on a smaller scale; and the scale of the manoeuvres would be the same as that of the models, so that the step from the models to the large ships would be easy ; and familiarity with the working of the ships as well as the models under ordinary circumstances would prepare the officers for using the ships in an actual fight as they have been accustomed to use the models in their friendly encounters. The scheme here proposed has its parallel in military schools. Although “autumn manæuvres” and sham fights afford soldiers a much better opportunity of preparing themselves for battle than any thing at present within reach of the sailors, still the war game appears to be growing in favour, and this is nothing more than practising mancuvres in miniature.
Independently of their value as a means of training naval officers, such models would afford a means of studying naval tactics. From them might be learnt the way in which a ship should strive to approach another of nearly equal power and speed, so as to use her ram to the greatest advantage ; and of tbis as yet but very little can be known; and, except on models, it can only be learnt from experiments on the ships.
Important as are the laws which have been verified by the Committee on the steering of screw-steamers, it appears to me that the most important lesson to be learnt from their investigation is, that there is nothing capricious in the behaviour of these ships. To realize the value of this lesson the investigation must be followed up; and it appears that the best way to do this would be by the aid of model launches on the plan thus roughly sketched out.