Katori (1982, 1983). Development of the trap has continued at CERC, including 

 mounting of the streamers on various types of racks (Kraus 1987) and optimi- 

 zation of the trap nozzle geometry (Rosati and Kraus 1988, 1989). Although 

 the wide -base SUPERDUCK racks shown in Figures 6 and 7 were stable under rela- 

 tively high waves, trap operators preferred the less awkward rectangular racks 

 used at DUCK85 (see Kraus, Gingerich, and Rosati 1989). 



20. The nozzles on the traps used at SUPERDUCK had a width of 15 cm and 

 a height of 2.5 cm, with a 9. 5 -mm- thick stainless steel "hood" 5.1 cm in 

 length (Figure 8). Nozzles were attached to the trap racks by 6.4-mm stain- 

 less steel mounting bars welded to the nozzles that were positioned in 

 circular fasteners on the trap frame and secured in place with duct tape 

 (Figure 7). 



21. During the DUCK85 data collection project (Kraus, Gingerich, and 

 Rosati 1989) , highly favorable sea conditions characterized by "clean" swell 

 with moderate wave heights facilitated extensive measurements of the variation 

 of the longshore sand transport rate through the surf zone. Traps were posi- 

 tioned from near the shoreline to the breaker line, with two current meters 

 located at representative locations in the surf zone, and sand transport was 

 measured for 5- and 10-min periods. These measurements resulted in a high- 

 quality data set on the cross -shore distribution of the longshore sand trans- 

 port rate, which could be integrated to obtain the total transport rate as a 

 function of representative wave and current conditions. This method of 

 measuring sand transport, in which traps are positioned across the surf zone, 

 is referred to as the Spatial Sampling Method (SSM) . 



2.5 cm 



15 cm 5 - 1 cm 

 Figure 8. SUPERDUCK streamer nozzle 



19 



