first of these depths (w^ter level at plus 1.75 feet MSL) is equivalent 

 to that at mean high water at Narragansett Pier, and is believed to 

 simulate ordinary storra conditions. The 8 foot level was selected as 

 that more nearly approximating a true hurricane condition. For each 

 water depth two wave periods (9 and 15 seconds) were tested for waves 

 up to 30 feet in height about 1 mile offshore (prototype). The actual 

 wave heights, periods, and water levels tested are given in Table 1. It 

 is to be noted that the values below and any other numerical values of 

 the model tests mentioned in this report are expressed as prototype 

 figures. 



TABLE 1 



TABULATION CF PROrOTYPE CONDITIONS TESTED 



Period (T) 

 (seconds) 



Wave Heights in Feet 

 Water aepth 1.75 feet above MSL 



9 

 15 



30 

 30 



25 



20 

 20 



15 

 15 



10 

 10 



Water depth 8 feet above MSL 



15 



30 

 30 



20 

 20 



15 

 15 



10 

 10 



Test Equipment and Procedure 



The model wave tank used for the tests was 96 feet long, 1-1/2 feet 

 wide and 2 feet deep. The wave generator was a vertical bulkhead -pus her 

 type and was powered by an electric motor controlled by vari-drive speed 

 control. 



Parallel wire resistance type wave gages and Brush recording equip- 

 ment were utilized to measure wave height and set-up. Measurement of 

 wave set-up employed a normal wave gage contained in a plastic stilling 

 basin just large enough to house the gage probes. Near the bottom of 

 the stilling basin a small hole allowed water to enter or leave the 

 stilling basin during the course of the wave action. The stilling basin 

 damps out the major portion of the wave oscillation and thus renders a 

 more accurate determination of the average still water level. 



The schematic drawing, Figure 3, shows four wave set-up measuring 

 stations. Actually, however, only two gages, one fixed and the other 

 movable, were utilized to measure wave set-up at the four stations. This 

 was done by leaving one gage in a fixed position for three constant con- 

 dition runs during which time the movable gage was shifted for the second 

 and third of the three runs. In this manner, three independent measure- 



14 



