and bar form, with a shallower area existing south of the photopole line and a 

 deeper region just north of the photopoles. Spilling breakers mainly predomi- 

 nated in the south region, while plunging breakers occurred to the north. The 

 bathymetry became smoother during the course of the data collection period, 

 making the breaking wave conditions more uniform from north to south. The 

 surf zone bottom consisted of a fine-grained sand substrate with a median 

 grain size of 0.17 mm. 



17. The mean water level referenced to NGVD was obtained at 6-min 

 intervals from a tide gage located at the seaward end of the FRF pier (Appen- 

 dix A, Table A3). The maximum tidal variation observed during the project was 

 approximately 1.4 m (Figure 3). Local mean water levels across the surf zone 

 are tabulated in Ebersole and Hughes (in preparation) for individual data 

 collection runs. 



Surf zone currents 



18. Water flow was measured with two 2 -component Model 551 Marsh - 

 McBirney electromagnetic current meters. The meters were mounted on tripods 

 and connected to shore by cable to recorders located in the instrument 

 trailer. The tripods (Figure 5) were made of 1.9 -cm stainless steel rods and 

 stood approximately 1.5 m high. The lower ends of the tripod legs were sunk 

 into the bed to a depth of about 10 cm by shaking the tripod back and forth 

 and applying downward pressure. A tripod with current meter attached was 

 easily moved by two individuals, permitting its rapid relocation in the surf 

 zone in response to varying tide level, wave conditions, and current charac- 

 teristics. An adjustable collar on the tripod held the metal cylinder housing 

 the meter electronics and preamplifier, allowing vertical adjustment of the 

 current meter sensor. The flow meter sensor was placed 20 to 30 cm above the 

 bed in all deployments. The horizontal axis of the current meter was aligned 

 with its y-component parallel to the trend of the shoreline. The current 

 meters sampled at 5 Hz and recorded for a 10- to 84-min period, depending on 

 the length of the sand- trapping run. 



Data collection procedure 



19. Longshore sand transport rates were measured by means of portable 

 traps such as shown in Figure 6. A schematic of the trap is given in Figure 7 

 with only two streamers shown for clarity. The sand collection element of the 

 trap consisted of a metal frame or nozzle to which a cylindrical bag of 



16 



