points on the Narragansett Pier shoreline) were plotted using the 

 hydrographic data on the U. S. Coast and Geodetic Survey boat chart 

 H-8315. The locations of the Your points mentioned above, indicated 

 in Figure 2 (map inset), were selected so as to blanket the Narra- 

 gansett Pier shoreline. The general location of this area is shown 

 on U. S. Coast and Geodetic Survey chart 1210. The actual profiles 

 extend from the MHW line to a water depth of 90 feet (MLW). The two 

 profiles at each of the four points on the shoreline referred to 

 above. Figure 2 (map), have bearings of N 73° W and N 62° W, respec- 

 tively. These directions were chosen to correspond with storm wind 

 directions for the 1938 hurricane at 1400 and 1500 EST respectively, 

 as determined from the isotach charts (Figure 1). As shown in Figure 

 2 (map) the four profiles at the two locations in the northern sector 

 have a sandy shoreline, whereas the four profiles at the two locations 

 in the southern sector have a rocky shoreline. 



The profiles described above were superposed on a common plot for 

 each direction and averaged in order to arrive at a profile which would 

 be representative of the average offshore hydrography at Narragansett 

 Pier (see Figure 2). The averaging process was carried out by select- 

 ing a common (equal) distjuice seaward of the MHW line for each profile 

 and then averaging the respective depths of the several profiles at 

 this point. This process was repeated until a sufficient number of 

 points had been obtained to plot the average profile. The average 

 profile determined from the data is shown on Figure 3 (dashed line). 



Model Beach Installation 



The average offshore profile at Narragansett Pier, derived as 

 described in the preceding section, was divided into four straight line 

 sections, making construction of the simulated profile in the wave tank 

 more convenient. The selected scale of 1 to 75 was a compromise among 

 several factors. These were tank dimensions, distance offshore or 

 depth where bottom has a significant effect on the wave characteristics, 

 and the assurance of' sufficient depth in the model to permit generation 

 of the wave heights desired for testing. 



The actual bottom surface of the model profile was smooth concrete 

 (3 to 1 mixture of fine sauid and cement). The concrete layer 1/4 to 

 1/2 inch thick was applied directly to a sand foundation previously 

 molded to the approximate slopes desired. As seen ftom Figure 3, the 

 straight line portion of the beach slope farthest seaward was not modeled 

 to scale but was arbitrarily selected and installed as a 1 on 16 slope. 

 in selecting this slope for the most seaward section of the model pro- 

 file, the assumption was made that the wave chjiracteristics in the two 

 systems, natural Jind model, were similar at the shoreward end (top) of 

 the 1:16 slope. The prototype water depth at this, point was 50 feet. 



Wave and Water Level Conditions 



Two water depths were investigated for wave set-up in the test pro- 

 gram. These were for water levels at 1.75 and 8 feet above MSL. The 



