NOTES ON THE PERFORMANCE OF THE S. S. TYLER. 89 



Besides the Old Dominion Steamship Company and the builders of the vessel, 

 Naval Constructor D. W. Taylor and the Newport News Shipbuilding Company had 

 a hand in preparing the lines of the vessel. 



Turning to the propeller side of the question, the propulsive efficiency at 12^ 

 knots is seen to be some 63 per cent, which, I think will be admitted, is a good per- 

 formance. 



In warship trials, an accurate curve of effective horse-power is generally avail- 

 able, but only very rarely for merchant ships; this fact renders the Tyler's trials 

 decidedly more interesting. 



The propeller data will be found in Table i ; the builders were responsible for 

 its design. 



The mean depth of water on the course was some 165 feet; information from 

 shoal water trials shows that this is an ample depth for the draught and the speeds 

 attained; the results are therefore not complicated by shoal water effects. The 

 mean depth on the approaches was about 1 10 feet and this figure also is reasonably 

 satisfactory. The approaches refer to a length of one mile each side of the range 

 buoys. Minimum suitable depth for this vessel is about 125 feet. The service in 

 which these vessels are engaged is a coastwise one, between New York City and 

 Norfolk, Virginia. 



Plates 49, 50 and 51 show clearly the easy entrance and run and the conse- 

 quent absence of heavy wave-making. These photos are by Mr. Higgins. 



Since the vessel has been in service she has made frequent trips at a mean 

 draught of 17 feet, and has made a speed of slightly over 12 knots between the 

 lightships. I hope Mr. Higgins will be able to supplement these figures with later 

 data on her sea performances. 



Table i. 



Hull and Machinery Data. 



m. 



Length over all 344 ft. o 



Length between perpendiculars, W. L 331 ft. o in 



Beam, molded 47 ft. o in 



Depth, molded ; 315 ft. o in 



Draught, aft, on trial 17 ft. 1 1 in 



Draught, forward, on trial 15 ft. 1 1 in 



Draught, mean, on trial 16 ft. 1 1 in 



Trim by stern 24 in 



Corrected displacement (long tons) 4,875 



Freight earning deadweight (long tons) 2,350 



Block coefficient ,650 



Longitudinal coefficient 682 



Wetted surface (square feet) 20,000 



