Page 74 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

Chapter 3: Search and Survey 53
divers observe the seabed and record and mark material as they proceed (Figure 3.17). The swimline, ideally, should be positioned some distance above, but within good visual sight of the seabed. As a very general rule, the height above the seabed should be half the diver separation. This way each diver searches half of the search area belonging to the diver on either side. This ensures that any particular area is visually searched by two divers, and thus there is a high certainty of sighting an object. In some cases, it may be necessary to alter the distances to improve efficiency. However, it should be emphasized that a diver can all too easily overlook the presence of an artifact, which is probably heavily encrusted with marine growth. Secondly, the distance of the search above the seabed should not be too great or the divers will not be able to spot the artifacts.
Figure 3.17 Swimline schematic at Cape Andreas, Cyprus, showing four divers holding the swimline and the first diver following the jackstay. The team has been deployed from the boat at the surface starting from the buoy at the buoy line.