422 eepokt— 1878. 



interfere with the action of the rndder during the interval of stopping y 

 and it is as regards this point that the most important light has been thrown 

 on the question of handling ships. It is found an invariable rule that, 

 during the interval in which a ship is stopping herself by the reversal of 

 her screw, the rudder produces none of its usual effect to turn the ship, 

 but that, under these circumstances, the effect of the rudder, such as it is, 

 is to turn the ship in the opposite direction from that in which she would 

 turn if the screw were going ahead. The magnitude of this reverse effect 

 of the rudder is" always feeble, and is different for different ships, and 

 even for the same ship under different conditions of loading. 



It also appears from the trials that, owing to the feeble influence of 

 the rudder over the ship during the interval in which she is stopping, she 

 • is then at the mercy of any other influences that may act upon her. Thus 

 the wind, which always exerts an influence to turn the stem (or forward 

 end) of the ship into the wind, but which influence is usually well under 

 control of the rudder, may, when the screw is reversed, become para- 

 mount and cause the ship to turn in a direction the very opposite of that 

 which is desired. Also the reversed screw will exercise an influence, 

 which increases as the ship's way is diminished, to turn the ship to star- 

 board or port according as it is right or left handed ; this being particu- 

 larly the case when the ships are in light draught. 



These several influences — the reversed effect of the rudder, the effort 

 of the wind, and the action of the screw — will determine the course the 

 ship takes during the interval of stopping. They may balance, in which 

 case the ship will go straight on, or any one of the three may predominate 

 and so determine the course of the ship. 



The utmost effect of these influences, when they all act in conjunction, 

 as when the screw is right-handed, the helm starboarded, and the wind 

 on the starboard side, is small as compared with the influence of the 

 rudder as it acts when the ship is steaming ahead. In no instance has a 

 ship tried by the Committee been able to turn with the screw reversed on 

 a circle of less than double the radius of that on which she would turn 

 when steaming ahead. So that, even if those in charge could govern the 

 direction in which the ship will turn while stopping, she turns but slowly ; 

 whereas in point of fact those in charge have little or no control over 

 this direction, and unless they are exceptionally well acquainted with the 

 ship, they will be unable even to predict the direction. 



It is easy to see, therefore, that if on approaching danger the screw 

 be reversed, all idea of turning the ship out of the way of the danger 

 must be abandoned. She may turn a little, and those in charge may 

 know in which direction she will turn, or may even by using the rudder 

 in an inverse manner be able to influence this direction, but the amount 

 of turning must be small, and the direction very uncertain. 



The question, therefore, as to the advisability of reversing the screw 

 is simply a question as to whether the danger may be better avoided by 

 stopping or by turning ; a ship cannot do both with any certainty. 



Which of these two courses it is better to follow, must depend on the 

 particular circumstances of each particular case, but the following con- 

 siderations would appear to show that when the helm is under sufficient 

 command there can seldom be any doubt. 



A screw steam-ship when at full speed requires five lengths, more or 

 less, in which to stop herself ; whereas by using her rudder and steaming 

 on at full speed ahead, she should be able to turn herself through a quadrant, 



