xliv 

 AUGUST 14th, 1907. 



COLLISIONS AT SEA. 



HOW THEY ARE CAUSED. 



'HAED A-POET; FULL SPEED 

 ASTERN." 



A meeting of the Royal Society of Tas- 

 mania was held on August 14. Mr. Ber- 

 nard Shaw, I.S.O., presided over a gather- 

 ing which scarcely numbered a score, 

 owing to the meeting clashing with other 

 functions taking place in the city that 

 evening. His Excellency the Governor 

 sent a letter of apology for his non- 

 attendance. 



Mr. VV. F. Ward read a paper upon 

 "The effect of reversing the screw on 

 the steering qualities of a ship, with an 

 explanation of the Togo-Alice collision.' 

 He feared that neither the navy nor tlie 

 mercantile marine had yet assimilated 

 the vital facts bearing on collisions with 

 which he dealt. It this opinion were 

 wrong its expression could do no harm; 

 if right, much good should result. He 

 began with an illustration. One night 

 in April last, when the steamer Togo was 

 going down the River lamar, and tne 

 yacht Alice was steaming towards her, 

 both going at full speed, the captain of 

 the Togo judged that a collision was 

 practically inevitable, and gave the or- 

 ders "Hard a-port;'' ••Full speed astern. 

 These were promptly carried out, the 

 collision was duly brought about, and 

 ten valuable lives were lost. The cor- 

 rectness of these orders had not been 

 questioned, in or out of court, and it 

 might be assumed, therefore, that they 

 were generally regarded, even to this 

 day, as safe and proper under similar 

 circumstances of impending collision. Ho 

 would submit, however, reasons for be- 

 lieving that these two orders combined, 

 so far from making for safety, were, in 

 their combined effect, the actual and 

 direct cause of an otherwise avoidable 

 collision. Not only this, but that, in 

 similar circumstances, these orders were 

 wrong in principle, that they have led to 

 many collisions in the past, and unless 

 discredited, would lead to more in the 

 future. 



These reasons were founded on actual 

 experimental results obtained by a Brit- 

 ish Association committee, whicdi con- 

 sisted of Sir W. Thomson, F.E.S. (now 

 Lord Kelvin), Professor Osborne Rey- 

 nolds, F.R.S., Mr. J. E. Napier, F.R.S., 

 and Mr. W. Froude, F.R.S. 



FoUovvdng up a series of experiments 

 on models by Professor Reynolds (report 

 of B.A., 1875) this committee reported 



(187(J) as follows:— "The experiments of 

 the committee on large ships have com- 

 pletely established the fact that the re- 

 versing of the screw of a vessel, with 

 full way on, very much diminishes her 

 steering power, and reverses what little 

 it leaves, so that where a collision is 

 imminent, to reverse the screw a,nd use 

 the ruader as if the ship would answer 

 to it in the usual manner, is a certain 

 way of bringing about the collision, and 

 to judge from the accounts of collisions, 

 this is precisely what is done in nine 

 cases out of ten." 



Further, the committee went on to re- 

 port : "it appears that a ship will turn 

 faster, and for an angle of 30deg., in 

 less room when driving full speed ahead, 

 than with her engines reversed, even if 

 the ruciuer is rightly used. Thus when 

 an obstacle is too near to admit of stop- 

 ping the ship, then the only chance is to 

 keep the engines on full speed ahead, 

 and so to give the rudder an opportunity 

 of doing its work." 



The speaker illustrated his address 

 with diagrams. The first showed approxi- 

 mately the effect of reversing the screw 

 of one of the experimental vessels. The 

 screw was reversed at a point called E, 

 and the vessel was in position D at the 

 time when she had lost half her way. 

 Another point (C) showed the position 

 I'eached in the same time when the screw 

 v/as not reversed, the helm in each case 

 being hard a-port. By the time she had 

 lost all way this vessel was heading ^') 

 degrees to port of her original direction, 

 whereas had her screw not been revers- 

 ed she would have headed 60 degrees to 

 starboard, so that the total effect of le- 

 versing was to turn her through 90deg. 



The committee, he stated, said: "'A 

 glance at the diagram is sufhcient to 

 show what a fatal mistake it must be, 

 when a collision is imminent, to reverse 

 the screw, and then use the rudder as if 

 the ship would asnwer to it in the usual 

 manner." A second diagram was a 

 sketch applying these experimental re- 

 sults to fairly meet the evidence given 

 at the inquest, although much of this 

 Mas contradictory. The first point (A) 

 suggested the position the Togo would 

 have reached had her screw not been 

 reversed; the second (B) her possible po- 

 sition owing to reversal; and the third 

 (E) where her screw was reversed. The 

 Alice was heading for the bank, and the 

 Togo was shown striking her practically 

 at right angles, as stated by her captain. 

 That something like this must have 

 taken place was supported by the fact of 

 the collision occurring at right angles, 

 ifor it was known that the vessels' lielms 

 were both hard a-port. If both were 

 answering their helms properly it would 

 appear that, if they struck at all, they 



