Sec. 52.3 



FLOW PATTERNS AROUND SHIPS 



241 



T,,- 0.689 F„- 0.205 



Fig. 52. C Observed Wave Profiles on Srap and Model for Paddle Steamer Minerva 



-Ship 



Paddle Steamer LUCINDA 

 Lw, -165 ft V = I2.325 nj^'^^^ Tq- 0.960 F„- 0.286 At-Rest Woterline, Positiojl. 



AP \9 ~\^ S lE 15 14 iS i^^ 1*1 10 9 8 7 6 5 4 3 2 1 

 Fig. 52.D Observed Wave Profiles on Ship and Model for Paddle Steamer Lucinda 



the bow-wave crest) at about 0.93L [SBMEB, 

 Mar 1953, p. 159]. The 7", value at this speed, for 

 an estimated length of 280 ft, is 1.077; Fn is 0.321. 



In the discussion of an old paper by Professor 

 J. H. CotterHl entitled "On the Changes of Level 

 in the Surface of the Water Surrounding a Vessel 

 Produced by the Action of a Propeller and by 

 Skin Friction" [INA, 1887, Vol. 28, p. 298], there 

 is some comment by Mr. F. P. Purvis concerning 

 the profiles of the waves alongside both models 

 and ships driven by paddlewheels. He mentions 

 an lESS paper for 1884-1885, having to do with 

 the paddle steamer Lucinda. Messrs. William 

 Denny and Brothers, Ltd., of Dumbarton, 

 Scotland, kindly furnished the author Avith 

 drawings showing wave profiles of the paddle 

 steamer Minerva as well as of the Lucinda. Figs. 

 52. C and 52. D were prepared from these drawings. 



E. P. Panagopulos and A. M. Nickerson, Jr., 

 give a partial wave profile (at the stern) as ob- 

 served on the large tanker Chryssi [SNAME, 

 1954, Fig. 13, p. 217]. 



52.3 Wave Profiles Alongside Models. It has 

 been customary, since the early days of model 

 testing in basins, to record the shape and position 

 of the wave profile along the model at selected 

 speeds. Typical modern photographs showing this 

 feature are reproduced in Figs. 78.A and 78.B. 

 Projections of the wave profiles on a transverse 

 plane are shown on the body plans for a number 

 of models on SNAME RD sheets 15, 16, 17, 18, 

 20, 95, 96, 97, and 98. RD sheet 144 shows a 

 wave profile projected on the centerplane. 



A rather familiar, but not often remembered 

 model wave profile is that first published by 

 W. Froude in 1877, in his first paper on parallel 

 middlebody [INA, 1877, Vol. XVIII, PL VI]. 

 It was reproduced by R. E. Froude four years 

 later [INA, 1881, Vol. XXII, Fig. lb, PL XVI]. 

 The model represented a ship having a length 

 of 500 ft, a beam of 38.4 ft, a draft of 14.4 ft, 

 and a length of parallel middlebody of 340 ft, 

 or 0.68L. It was run at a T, of 0.645, F„ = 0.192. 



Wave profiles of three models tested in the 

 Michigan basin at Ann Arbor are given by H. C. 

 Sadler [SNAME, 1907, Vol. 15, PL 10]. The 

 pubhshed data are among the few which state the 

 speed-length quotient at which the ship or model 

 was run. However, the values of T, were so low 

 that the profiles do not have prominent crests 

 and troughs. 



Wave profiles alongside a 39.37-ft self-propelled 

 steel launch (considered here as a large model) 

 are given by S. Yokota, T. Yamamoto, A. Shige- 

 mitsu, and S. Togino in Fig. 18 on page 328 of a 

 paper entitled "Pressure Distribution over the 

 Surface of a Ship and its Effects on Resistance" 

 [World Eng'g. Congr., Tokyo, 1929, Proc, Vol. 

 XXIX, Part 1, publ. in Tokyo, 1931]. Attention is 

 invited to the comments on pages 297 and 298 

 concerning difficulties encountered in recording 

 these profiles. Nevertheless, the published data 

 include profiles for two conditions, (1) with the 

 launch driven by its underwater propeller and 

 (2) with it driven by an abovewater airscrew. 



Three sets of wave profiles around models \vith 



