requires a boat crew of two and a four-man coring crew to navigate the 

 vessel and operate the 5-ton crane used to lower and raise the core 

 apparatus between the deck and sea floor. The three legs on the barge, 

 which are hydraulically operated from the pilot house, enable the barge 

 to be raised above the sea and swell to provide a stable coring platform. 



d. Data Collection Planning . Before the field data collection 

 effort, tentative offshore seismic survey tracklines were established 

 and plotted on navigation charts of the survey area. Position, spacing, 

 and length of the tracklines were determined by several factors. A pri- 

 mary concern was spacing the lines to achieve maximum coverage of the 

 study area. The inshore boundary was approximately the 5 -meter depth 

 contour which is about the minimum depth for obtaining good quality 

 seismic profiles; the seaward boundary was about 8 kilometers offshore 

 which was judged to be the economic limit for sand transport to project 

 beaches . 



A second factor was to lay out the seismic lines so that buried 

 stream channels, relict barrier islands, tidal shoals, river deltas, and 

 other geologic features with a high potential for containing sand would 

 be crossed and show on the seismic profiles. Preliminary core sites 

 were selected on the basis of bathymetric information; however, final 

 core sites were chosen after all the seismic data were collected and 

 subjected to preliminary interpretation. After the survey tracklines 

 were selected, the locations of the shore stations for the navigation 

 system were determined. Of high priority were stations at elevated 

 positions (for adequate line-of-sight) which also offered good triangu- 

 lar position in relation to the survey ship and adjacent shore stations. 

 (Optimum geometry is achieved when the angle of range intercept of the 

 vessel is greater than 30° and less than 150°; optimum range angle 

 intercept is 90°.) After shore stations were determined and plotted on 

 map sheets, their positions were accurately surveyed. A total of eight 

 shore navigation stations were used along 85 kilometers of coast. Occa- 

 sionally, positions and spacing of the predetermined tracklines were 

 altered to gather additional information on geologic features such as 

 buried stream channels, sediment contacts, and sea floor outcrops of 

 possible sandy material. 



After approximately 435 kilometers of seismic profile records was 

 collected, preliminary analysis and interpretations were made to select 

 coring sites with the greatest potential, based on past experience, for 

 retrieving sandy material. Use of seismic data to decipher geologic 

 conditions before selecting final core sites enables their selection to 

 be based on the best information available. Thus, this procedure maxi- 

 mizes the usefulness of both sources of data and provides the most 

 efficient use of funds. 



During phase II the Vollert, with the positioning system on board, 

 was used to relocate fix positions selected as coring sites. This was 

 done by duplicating the range values from the shore stations. The 

 YolZevt first maneuvered until one of the ranges was duplicated and then 



17 



