70-1 



HYDRODYNAMICS IN SHIP DESIGN 



Sec. 73.26 



velle Turbonavi Veloci (Preliminary Notes on 

 Variations, due to Reciprocal Influence, in the 

 Power Absorbed by the Cooling (Condensing) 

 Water and by the Propulsion Plant in High-Speed 

 Turbine-Driven Ships), Ann. Rep. Rome Model 

 Basin (in TMB library), 1936, Vol. VI, pp. 67-76 



(13) Orlando, M., "La Circolazione ai Condensatori nel 



Naviglio Veloce (The Circulation in the Con- 

 densers of High-Speed Ships)," Ann. Rep. Rome 

 Model Basin (in TMB library), 1936, Vol. VI, 

 pp. 76-90 



(14) Reilly, J. R., and Hewins, E. F., "Condenser Scoop 



Design," SNAME, 1940, pp. 277-293; 301-304. 

 This is an excellent, comprehensive, detailed dis- 

 cussion of the problem of designing inlet and dis- 

 charge scoops, with a great deal of e.\perimental 

 and design data and an example worked out for a 

 pair of inlet and outlet scoops. The text is supple- 

 mented by numerous flow diagrams. 



(15) TMB Report R-43 of September 1941 entitled "The 



Effect of the Flow of Water Through Condenser 

 Scoops on the Resistance of a Destroyer Model." 



(16) A theoretical discussion of the water flow into scoops 



of various shapes, in which flow nets have been 

 prepared by conformal and Schwartz-Christoffel 

 transformations, is given by C. Igonet in ATMA, 

 1945, Vol. 44, pp. 447-466. So far as known no 

 translation is available. 



(17) BuShips Translation 529, of article entitled "Esper- 



ienze Aerodinamiche su Modelli di Booohe di 

 Presa per I'Acqua di Raffreddamento dei Con- 

 densatori Marini (Aerodynamic Tests on Models of 

 Intake Scoops for Cooling Water of Marine 

 Condensers)," by Dr. B. Lattanzi and Dr. E. 

 Bellante, Aerodynamic Laboratory of Guidonia, 

 26 Jul 1941 



(18) Frick, C. W., Davis, W. F., Randall, L. M., and 



Mossman, E. A., "Experimental Investigation of 

 NACA Submerged Duct Entrances," NACA Rep. 

 ACR A5I20, Oct 1945 



(19) Breshn, J. P., and Ellsworth, W. M., Jr., "Progress 



Report: Research on Main Injection Scoops and 

 Overboard Discharges," TMB Rep. 793, Sep 1951 



(20) Spannhake, W., "Comments and Calculations on the 



Problem of the Condenser Scoop," TMB Rep 790, 

 Oct 1951. 



Pertinent design notes on discharge openings 

 are given by E. P. Worthen, with a drawing of the 

 device used on the Manner class of the 1950's 

 [SNAME, 1953, Fig. 43, p. 201]. 



73.26 Design and Installation of Galvanic- 

 Action Protectors. It can not be expected that 

 carefully shaped bossing and skeg terminations, 

 strut arms and hubs, rudder posts, and other 

 fixed appendages will give creditable hydro- 

 dynamic performance if cluttered up with 

 excrescences in the form of galvanic-action pro- 

 tectors, studs, nuts, and what not. It appears 

 probable that these protectors will have to be 

 fitted for some time to come. Their installation 



should call for a measure of design and construc- 

 tion effort comparable to that devoted to the 

 bossing, strut, and propeller design. The use of 

 partly recessed zinc plates, socket-head cap 

 bolts, shoulder nuts, and similar devices is one 

 step toward improvement, indicated in Fig. 73. S. 



Limit Line for Wastage Before (?eplacement 



Chamfer Outside Edaes All Around Reaordlcss of 



Flow Direction 

 Elastic 



Nf45dei] 



Stop Nut 



y'inch Stud 



MQ>y Be End-Welded Studs With Arc-Initiating Material 2 

 ^45 (^q All Dimensions ore in Inches 



Fig. 73. S Proposed Fairing and Attachment of 

 Galvanic-Action Protectors 



Certainly there appears little excuse, in an age 

 which prides itself on its technologic achieve- 

 ments, for the addition of fully protruding 

 protectors on any ship which spends a reasonable 

 proportion of its life underway. 



In areas of the waters of the world where 

 corrosion of the steel hull plating is exceptionally 

 severe, this corrosion is often reduced to small 

 proportions by bolting rows of plates or blocks of 

 anodic materials directly to the shell plating 

 [Kurr, G. W., "Check Costly Hull Corrosion," 

 Mar. Eng'g., Nov 1954, pp. 57-60, also p. 12]. 

 The added drag of these excrescences is un- 

 doubtedly large. However, it might well be less 

 than the added friction drag of the loose bottom 

 paint and the severely pitted plating surfaces 

 which would be encountered without the anodic 

 protectors. 



Other methods involving external devices in 

 the form of appendages, temporary or permanent, 



