Sec. 78.9 



MODEL-TESriNG PROGRAM FOR A SHIP 



Fig. 78.F Fish-Eye View of Arch-Stern Model in Circulating- Water Channel 

 Some cross flow is visible under the flat bottom of the side skegs. 



abreast the propeller disc. (This was not fully 

 accomplished; see Fig. 60. M). 



Actually, the transom-stern model was not 

 checked for flow in the circulating-water channel 

 because of the good flow pattern indicated on the 

 bare-hull model. The TMB work schedule was 

 such that the circulating-water test of the arch- 

 stern model was not made until all appendages 

 were fitted and the model was self-propelled. 

 Figs. 78. E and 78. F are through-the-water photo- 

 graphs of the after portion of the ABC arch- 

 stern model, TMB 4505-1, taken in the TMB 

 circulating-water channel. Other than a slight 

 cross flow under the flat bottoms of the skegs, 

 the water passes easily and regularly through the 

 tunnel and around the skegs. 



Sinkage and trim data on the transom-stern 

 model with appendages, when both towed and 

 self-propelled, are plotted in Fig. 58.B. Wake- 

 survey data are plotted in Fig. 60. M and analyzed 

 in Fig. 60.N. 



78.9 Self-Propelled Tests. Self-propulsion 

 tests are to be run on both models, carrying all 

 appendages except the condenser intake and 

 discharge, using stock propellers TMB 2294 and 

 1986, over the range of speed specified for the 

 resistance tests. The displacements are to be as 

 indicated in Table 78.c. It is not necessary to 



make SP tests with the stock propellers in the 

 partly loaded condition. 



It is desired that the Df correction [Bu C 

 and R Bull. 7, 1933, pp. 37-38] for all self-propul- 

 sion tests allow for a roughness of the clean, new 

 ship corresponding to a ACf of 0.30(10"^), as 

 applied to the ATTC 1947 or Schoenherr friction 

 values. No overload tests are required. 



When the results of the foregoing tests have 

 been worked up and evaluated, a new propeller 

 will be designed and built for the most promising 

 of the alternative designs. A new set of self- 

 propulsion tests is to be run, over the range of 

 speeds specified for the resistance tests: 



(1) At the full-load displacement, draft, and trim 

 condition 



(2) At the partly loaded conditions, with dis- 

 placement, draft, and trim by the stern to be as 

 specified subsequently. 



Fitting-room photographs are to be taken of the 

 sterns and after quarters of both models to show 

 the shape of the hull and arrangement of append- 

 ages. 



The new propeller for the transom-stern ABC 

 ship is designed in Chap. 70 by the Lerbs short 

 method. A new model was not built to this design. 



The stern appendages on the transom-stern 



