In the West Delta operation, the receivers were placed about 165 feet apart. Each 4-C unit weighs 75 pounds. The Schlumberger proprietary OBC system is called the Nessie 4-C multiwave array, which debuted for the company in the North Sea in 1996, according to Jason Robinson, the company's business development manager. This is where S-waves can often help to clarify the image. Infill shooting unnecessary.
Permanent emplacement is possible.
Having the second recording ship meant non-stop shooting for the source boat. One boat was always ahead of it laying cables, and one boat was always behind, recording and picking up the cables. Then the two vessels switched roles, back and forth, all day long, in north-south swaths across West Delta. By having cloned recording vessels we are constantly ahead of the shooting vessel. This is why we have been consistently efficient.