Appendix F 
Instrumented Sled 
The instrumented sled was equipped with a O- to 25- psir (psi relative to one 
atmosphere) Senso-Metrics pressure gauge, a resistance wire wave gauge, and 
five current meters arranged vertically. The current meters were mounted at 
elevations 0.35, 0.60, 1.00, 1.35, and 1.75 m above the bed on a diagonally 
sloping beam (Figure 7 of the Introduction section). The beam was parallel to 
the shoreline, so the meters were aligned at approximately the same cross-shore 
coordinate. The meters were spread over an alongshore distance of 
approximately 3.5 m. The sled was deployed so that the lower end of the 
beam was in the up-drift direction of the longshore current to reduce flow 
interference, such that the current meters were up-drift of the beam. A 
common timing pulse was used for all current meters to reduce interference 
between instruments for this close proximity deployment. They were aligned 
to measure longshore and cross-shore components of the current when the sled 
was towed out normal to the shore. The sled was also instrumented with a 
digital compass for orientation measurement, and a Met One anemometer. The 
data were transmitted via radio modem to a personal computer located in a van 
on the FRF pier. 
The sled was pulled offshore with the CRAB (Figure 8 of the Introduction 
section) and then incrementally retrieved, stopping at several cross-shore 
locations, with the FRF’s forklift. The sled was towed offshore past the 
breaker zone to a depth of approximately 3 m, typically to a cross-shore 
coordinate of 245 m. The runs were along a line just north of the primary 
cross-shore array and the retrieval stops were made adjacent to an instrument 
in the array, with three to eight stops for each cross-shore transect. Locations 
of the sled and the start time for each run are given in Table Fl. The position 
and orientation of the sled were recorded using an electronic total station which 
sighted two prisms located on the sled mast. 
At each sled position, data were collected for 34 min (except for run 
#SL1910A which was only 8 minutes long due to low battery). The collection 
period of 34 min was selected to provide a balance between the time needed for 
stable statistics on each run and to maintain a short enough transect time to 
assume Stationarity of the incident waves. 
Appendix F Instrumented Sled 
F1 
