254 



THEORY OF SEAKEEPING 



(o) More reliable evaluation of the demarcation lines 

 between moderate and severe ship motions. 



(6) Establishment of demarcation lines for each wind 

 speed and direction. 



(c) Comparison of seagoing qualities of various ships 

 at similar displacement/length ratios. 



An examination of the engineer's log is also suggested 

 in order to establi.sh the power reduction corresponding 

 to each demarcation line. Investigators' attention is 

 called to the fact that the weather log usually pro^'ides 

 more information on wind and waves than the deck log. 

 In general, all three logs should be examined: the deck 

 log, the weather log and the engineer's log. 



Tiie research suggested in the foregoing has a dual 

 ultimate purpose: 



(a) To indicate favorable ship forms and proportions. 



(6) To establish the engine power connnensurate with 

 the speed that .safely can be maintained in adverse 

 weather. 



Nomencloture 



The symbols listed at the end of Chapter 2 apply to 

 e(|uations connected with waves and ship motions. 

 Additional symbols used in Chapter 4 are as follows: 



DHP = delivered liorsepovver 



K, K' = amplification factors in heaving and pitching 



motions, Section 2.2 



/, III, n = directional cosines along .r, //, and z-axes 



N = propeller RPM 



SHP = shaft horsepower 



Sa = average apparent propeller slip 



7',( = time out of dock 



ir = weather factor 



A = ship displacement (weight) 



V = ship displacement (volume) 



/Clements, ecjua 



eciuation (22) 



Bibliography 



1 For the code of Abbreviations see page 1318 of 

 Chapter 3. 



2 All references listed under names of Kent and 

 Kempf in Chapter 3 are rele\'ant to the subject of Chapter 

 4. 



3 References preceded by 3 before the year will be 

 found in the Bibliography at the end of Chapter 3. 



4 Additional references and references particularly 

 pertment to the subject of Chapter 4 are listed below: 

 Aert.s,sen, G. (1957), "The Effect of Weather on the 



PerffH-mance of Cargo Ships," XSMB Symp., 1957, 

 pp. 388-401 and 931-950. 



Aertssen, G. (1959), "Sea Ti'ials on a Passenger-Cargo 

 Liner With Block Coefficient 0.672 and on a Large 

 Tanker With Block Coefficient 0.770," Trans. NEC, 

 vol. 75, 1958-59, pp. 165-190 and plates 1 to 4. Also 

 International Shipbuilding Fragress, \'ol. 0, no. 54, 

 I'ebruary 1959, pp. 76-91. 



Alien, W. G. and Sullivan, E. K. (1954), "Operation in 



Service of the Mariner-Type Ship," Trans. SNAME, 

 vol. 62, 1954, pp. 522-592. 



Bled.soe, Margaret D. (1958), "Speed Peduction in 

 Waves," DTMB 1083, April 1958. 



Bonebakker, .1. W. (1944), "tiber Dienstgeschwindig- 

 keiten von l''rachtschiffen." Schift' und ^V^^rjt, heft 

 1/2, .lanuar 1944, pp. 1-11. 



Bonebakker, J. W. (1951), "The Application of Statis- 

 tical Methods to the Analysis of Service Performance 

 Data," Trans. NEC, vol. 67, 1951, pp. 277-296 and 

 D115-D126. 



Bonebakker, .T. W. (1954), "Analysis of Model Experi- 

 ments, Trials and Service Performance Data on a 

 Single Screw Tanker," 7'mn.s. NEC, vol. 70, 1954, pp. 

 475-496. 



Clements, R. E. (1956-57), "A Method of Analysing 

 A'ovage Data," Trans. NEC, vol. 73, 1956-57, pp. 

 197-230 and D55-D64. 



Emerson, A. (1954), "The Application of Wave Resist- 

 ance Calculations to Ship Hull Design," INA, vol. 

 96, 1954. 



Inui, Takao and Maruo, Hajime (1957), Advances in 

 Calculation of Ware-Making Resistance of Ships, vol. 

 2 f)f 60th Anni\ersary Series, JZK, Tokyo, Japan, 

 1957. 



Jacobs, Winnifred R. and Lewis, Edward V. (1953), 

 "Cori'clation of Resistance Tests on Ship ^Models in 

 Short Waxes," SIT-ETT Note 222, prepared for 10th 

 ATTC, Cambridge, Mass., May 1953. 



Kempf, G., "Verhalten Verschiedener Schiifsformen im 

 Seegang," WRH, vol. 13, 1932, p. 176. 



Kempf, G. (1935), "Einfluss von Stampfbewegungen auf 

 den Fahrtwiederstand von Schiffen und den Antriebs- 

 giitegrad von Schrauben," JSTG, 36, band, 1935, pp. 

 199-224. 



Kent, J. L. (1958), Ships in Rough ]Vater, Thomas 

 Nelson and Sons Ltd., 19 East 47th Street, New York 

 17, N. Y. 



Korvin-Krouko\sky, B. V. and Jacobs, Winnifred R. 

 (1954), "Calculation of the Wave Profile and Wave- 

 making Resistance of Ships of Normal Commercial 

 Form by Guilloton's Method and Comparison with 

 Experiniental Data," SNAME, T. and R. Bulletin 

 No. 1-16, December, 1954. 



Kreitner, J. (1939), "Heave, Pitch and Resistance of 

 Ships in Seaway," Trans. INA, vol. 81, 1939, p. 203. 



Lewis, Edwai'd Y. (lU55a), "The Influence of Sea 

 Conditions on the Speed of Ships," Joiirn. ASNE, 

 vol. 67, no. 2, May 1955, pp. 303-319. 



Lewis, Edward V. (1955/*), "Ship Speeds in Irregular 

 Seas." Trans. SNAME, vol. 63, 1955, pp. 134-202. 



Lewis, Edward V. (1956a), "The Sea Speed of Cargo 

 Ships in Rough Weather Service," Intern. Shiphuild. 

 Progrs., vol. 3, no. 22, June 1956. 



Lewis, E. V. (1956*), "Status Report on Log Analysis 

 for Panel SO-3, SNAME," ETT Note No. 371, Janu- 

 ary 17, 1956. 



Lewis, Edward V. (1957), "Sea Speed of Victory Ship in 



