CHAPTER 56 



Observed Resistance Data for Models and Ships 



56 . 1 General Comments 297 



56.2 Resistance Data from Tests of Models of 



Typical Ships 297 



56.3 Systematic Resistance Data from Model 



Series; Taylor Standard Series with Con- 

 tours of fijj/A 298 



56 . 4 Japanese Fishing- Vessel Standard Series . . 300 



56 . 5 Gertler Reworking of Taylor Standard Series 



Data of 1954, with Contours of C^ . . . . 301 



56 . 6 Resistance Data for Very Fat Ships .... 303 



56.7 Systematic Resistance Data for Parallel- 



Middlebody Variations 306 



56 . 8 Resistance Data for Very Low Ship Speeds . 306 



56 . 9 Rate of Variation of Model Residuary Resist- 



ance with Speed 306 



56 . 10 Variation of Total Resistance of Model and 



Ship with Speed-Length Quotient .... 308 



56 . 1 1 Changes in Resistance with Changes of Trim 



and Displacement 312 



56.12 Measured Thrusts and Towing Pulls on Ships 312 



56.1 General Comments. This chapter gives 

 information as to the availabihty in the technical 

 literature of observed resistance data on models 

 and ships of many types, particularly those tested 

 as systematic or methodic series to determine the 

 effect of certain variables. Accompanying notes 

 indicate, where necessary, the location of the 

 lines or body plans of the models or ships. 



These data are supplemented by information 

 concerning the resistance of unusual ship forms or 

 of more-or-less standard forms run at unusual 

 speeds. 



Means are described for approximating the 

 resistance of ships when their exact shape is not 

 known, when they have not been tested at model 

 scale at the speed desired, or when their displace- 

 ments are different from the values for which 

 data are available. 



Some self-propulsion test data for typical 

 vessels, plus references to other published data, 

 are to be found in Chap. 60. In almost every case 

 these give the predicted effective power Pe for 

 the ship (or ship design) represented by the model. 



56.2 Resistance Data from Tests of Models of 

 Typical Ships. Attempts have been made from 

 time to time, by interested individuals, to list, 

 collect, and systematize the enormous mass of 

 pubhshed data on the resistance tests of models. 

 With so much time and energy devoted to this 

 particular field, in the model basins of the world 

 over the past seventy-five years, it is a pity that 

 only a fraction of the existing test data are in a 

 form usable for analysis and design, and in loca- 

 tions available to the naval architect and marine 

 engineer. 



The graphic data published by D. W. Taylor in 



the three editions of "The Speed and Power of 

 Ships" contain, in one form or another, the 

 resistance-speed curves of models representing 

 many forms and types of ships, usually as parts 

 of small groups or series. The period since World 

 War II has brought a reafization of the necessity 

 for more systematic presentation of data of this 

 kind, as witness the work of the Swedish State 

 Model Basin and of the David Taylor Model 

 Basin in reporting test data on numerous models 

 of vessels of a given class. There is also a wider 

 realization of the fact that, for analysis purposes 

 on the part of a number of workers, the most 

 comprehensive data on models and ships is none 

 too complete. 



A leader in this respect has been the Rome 

 Model Basin. In the annual reports of this 

 estabhshment ["Annali della Vasca Nazionale per 

 le Esperienze di Architettura Navale"], of which 

 Vols. I through XI are in the TMB library, there 

 are included very complete data sheets and 

 graphs giving the results of tests on selected ship 

 models of a rather wide variety of types. As 

 examples, there are included in Vol. X, published 

 in 1941, test results for six models constructed to 

 the order of various Italian firms. For these 

 models there are given: 



(a) Tables I and II, listing the principal dimen- 

 sions, form coefficients, and other data for from 

 one to five displacement and trim conditions on 

 each model 



(b) Tables III and IV, giving the observed drag 

 Rt and speed V for the six models, at different 

 displacements and trims, with water temperatures 

 and other necessary data 



297 



