SHIP MOTIONS 



197 



Legend 

 o Observations by Kent (23.24) 



• Suggesl-ed values by Kent (24) not result 

 of direct Observation 



+ Quoted by Bertain (14) from various 



Observers prior to 1873 

 ■ Observations by Schnadel (43.44) 

 A Observations by Bridges (48) 

 X Observations by Lockwood Taylor (34) 

 7 GLuoted by Gail!ard(20) from various 



Observers prior to 1904 

 D Observations by Vauglnan Cornish (19) 



• Observations on Ocean Vulcan Trials 



100 200 300 400 -500 600 700 



Wove Length in Feef 



600 



900 



1000 



1100 



1200 



Fig. 37 Maximum wave heights for various wave lengths (from Admiralty Ship Welding Committee, 1953) 



ship, its iii.strunu'iitatioii iiiid sca-dh.^crxatidii results. 

 The second lialf reported on wind-tunnel and towing- 

 tank results of tests made on a model of the SS Nissei 

 Mam. The lines and principal dimensions of the ship 

 are shown in Fi";. 42. The ship, completed in December 

 1951 , is drixen by a turbine with double-reduction gearing. 

 The ma.ximum continuous output is 4000 slip at 105 

 rpm, while the normal .service output is :i400 slip at 

 99 rpm. A single four-liladed jiropeller 17.2 ft diam 

 propels the vessel. 



The extensive instrumentation of the shii) is gi\-eii in 

 Table 8. There were two or three instruments for 

 measuring each characteristic of ship behavior. This 

 was a wise precaution because on previous voyages, such 

 as Schnadel's (1934) for instance, some important re- 

 cords were lost because of instrument failure in storm 

 conditions. 



The observational voyage totalled 129 days, from De- 

 cember 26, 1951 to May 3, 1952. This was the maiden 

 voyage of the ship from Yokohama to Vancouver, 

 Honolulu, Singapore, Bombay, Singapore and back to 

 Yokohama, a distance of 21 ,700 nautical miles. Through 

 most of the voyage the weather was mild, but the pa.s.sage 

 from Vancouver to Honolulu was very rough. Quoting 

 from the report: 



"Fully loaded with wheat, she sailed for India via 

 ^'okohonu\ at 17:30 on .lanuary 16, 1952, I'ollowing a 



south-west course along the boundary line in Load 

 Line Rule, turning dead west at point 34°55'N, 149°0'W, 

 at 5:20 on .lanuary 22nd, when she encountered heavy 

 storms e\'erv day, and terrific wind, with waves growing 

 in height. The \'oyage was so strenuous that the vessel 

 exhausted her fuel reser\-e and was obliged to abandon 

 the intention of proceeding direct to Yokf)hama and to 

 touch at Honolulu for bunker supjilies. 



"The ship turned toward Honolulu at 34°29'X, 

 170°25'W, at 1:30 on .January 2Sth, arri\-ing at Hono- 

 lulu at 9:15 on .January 31st. 



"Iiegular measurements of the ship's sea performance 

 were made three times daily at 9, 12 and 15 o'clock ha\'ing 

 regard to the light necessary for filming sea conditions. 

 After leaving Honolulu, regular measurements were made 

 only once a day at noon, as some members of the com- 

 mittee left the ship at ?Ionolulu, and very few recording 

 papers remained, and the sea conditions were thougiit 

 comparatively calm." 



The observational periods were of 3 min duration. 

 In addition progressive (step-wise) tests were conducted 

 six times during the \-oyage for measuring propulsi\-e 

 characteristics. 



The nature of wave measiu'ements is indicated by the 

 following quotation: "When the measurements were 

 taken, attention was concentrated on the irregularity 

 of the ocean waves thi'oiighout the whole voyage. The 



