Appendix A 
Surveying 
As in previous Duck experiments, surveying was a critical part of 
DELILAH. The CRAB was used to locate the instrument pipes and to survey 
the minigrid area. An additional survey was conducted of the bathymetry 
surrounding the FRF, out to a water depth of 13 m, using a combination of the 
CRAB and a survey sled. In this survey, referred to from here on as the “13- 
m-deep” survey, the sled was towed behind the FRF's amphibious Lighter 
Amphibious Resupply Cargo (LARC). Presentation of the data and 
descriptions of this survey and the minigrid surveys, as well as details about 
the survey equipment and sources of error follow. 
Coordinate System 
All survey data were collected relative to the FRF coordinate system, which 
has its origin located behind the duneline near the southern boundary of the 
FRF property. The baseline of this system (cross-shore distance = 0) is 
_ perpendicular to the FRF pier and is aligned 20 deg west of true north. 
Elevations were measured relative to the National Geodetic Vertical Datum 
(NGVD) of 1929. This datum is 0.42 m above Mean Low Water. 
Survey Equipment 
All DELILAH surveying was conducted with either a Zeiss Elta 2s * total 
station or a Geotronics Geodimeter 140-T* auto-tracking total station. 
Problems developed with each of these instruments, and it is important to 
understand what the problems were and their impact before using the 
DELILAH survey data. 
Zeiss Elta-2s 
The Zeiss system incorporates in one compact unit a first-order electronic 
theodolite, distance meter, microprocessor, rechargeable power supply, and an 
interchangeable solid state memory module. The instrument is manually aimed 
at a reflecting prism and a collimated infrared beam measures the distance and 
Appendix A Surveying 
Al 
