Page 78 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

Chapter 3: Search and Survey 57 immediately possible to see area that had been missed and to plan the fol-
lowing day’s survey to take this into account.
E. GPS SEARCH
In shallow water there is no reason why an underwater GPS system could not be used. All that is necessary is that the system should be waterproof, the diver should have access to the controls, and the antenna should float on the surface. In places where there is not a strong current it would be pos- sible to maintain the antenna on a cable running from the surface to the diver unit within a 5-m radius of the operator’s position. This would give access to reasonably accurate underwater location and, more important, the ability to utilize the simple tracking systems that most GPSs have.
IV. OTHER VISUAL TECHNIQUES
Several techniques are available to search for deep-water wreck sites. It must be pointed out immediately that the cost and logistic problems of working in deep water have to be carefully considered along with the objec- tives of the exercise. It may well be that even if a site is discovered in deep water, it may not be feasible to study it properly, let alone excavate it. With the advent of mixed gases and technical diving, the operational threshold of conventional archaeology is slowly extending into deeper water. For example, Bass et al. (1984) operated with conventional SCUBA to a depth up to 70 m in Ulu Burun, Turkey. Similarly, his work at Tektash was con- ducted at 42 m for three seasons. Naturally this requires resources and infra- structure, so if sites are going to be worked at this depth the ability to search for them is also necessary. Although the logistics of a survey are quire dif- ferent from a full-scale excavation, they are, nevertheless, serious. So any system that reduces the logistics of divers is worth considering.
A. SUBMERSIBLES
Several systems have been used that involve putting a person in some form of submersible. At the simplest level, a single, manned, one- atmosphere capsule, towed behind a boat, has been used in deep-water searches in the Mediterranean off Turkey (Bass and Katzev, 1968) and else- where in the Mediterranean (Frey et al., 1978). Otherwise, a number of exotic manned submarines and one-atmosphere diving suits have been