THE EFFECT OF PROPELLERS ON THE STEERING OF VESSELS. 429 



In the next vessel reported, the Cervin, it will be seen that the 

 screw was well immersed, and hence would probably exert no great in- 

 fluence when reversed to turn the vessel to starboard. At the commence- 

 ment of all the trials, however, the wind was blowing with force 5 on the 

 starboard side of the vessel, and the effect of this would be to cause the 

 vessel, as long as she had way on, to turn to windward, and this, it will be 

 seen, is what happened; in every case the vessel's head turned to wind- 

 ward. Here also the reverse influence of the rudder was apparent, for 

 the vessel turned faster to starboard with the helm starboarded than with 

 it ported. 



August 25, 187T. 



S.s. Cervin, of South Shields, length, 287 feet ; breadth, 34 feet ; 

 depth, 24 feet ; tonnage, 1913. Propelled by two engines of 180 h.p., 

 combined ; screw right-handed, 4 blades ; diameter, 14 feet 9 inches ; 

 pitch, 17 feet; draught of water, forward 21 feet 4 inches, aft 21 feet 

 9 inches ; top of blade of screw immersed in water, about 5 feet ; wind, 

 E.N.E. ; force, 5 ; sea smooth. 



Trial No. 1 (helm hard a-port). — Ship's head N. by W., going full 

 speed ahead, 9-^ knots, the engines were stopped and reversed, and helm 

 put hard to port ; ship's head came up to N. by E. in 2 minutes, and 

 remained steady on that point ; way through the water ahead stopped in 

 3 minutes 40 seconds. 



Trial No. 2 (helm hard a-starboard) . — Ship's head N. by E., it came 

 up to N.E. by E., or 45 degrees, in 4 minutes, and way stopped. 



Trial No. 3 (going fast astern, screw started to drive her ahead, helm 

 a-port). — Head N. by W., fell off to N.N.W. in 1 minute 30 seconds. 



Trial No. 4 (with helm a-starboard).— -Head at N.E., fell off to N.N.E. 

 in 2 minutes. 



Trial No. 5 (full speed ahead, helm amidships) — Head N. by W., 

 went slightly towards west, then back to north, in 3 minutes. 



J. Gillie. 



