Deeptowed photographic and acoustic surveys in the Pioneer Area in Central Indian Basin, resulted in collection of 52,295 photographs, 450 hours of video record and 1129 km of sub-bottom and side scan data. Data-processing involved two main approaches:
qualitative-delineation of areas with different features, such as nodules, crusts, biological activity etc., from observation of video record; and
quantitative - mapping of nodules and other seabed features from photographic and acoustic data. Mapping of nodules and other features (crusts, biological activity and sediment characteristics) was carried out by integrating the data from various sources, such as navigation, photographic and acoustic, keeping time as the reference, by specially developed softwares.
Extensive sampling and bathymetric surveys in the nodule areas of Central Indian Basin during the last decade resulted in allocation of 150,000 sq. km of "Pioneer Area II to India by the UNCTJOS III to carryout detailed exploration. However, further surveys were required using more sophisticated techniques that could provide new information and data in order to delineate commercially less viable areas within the Indian Pioneer Area, for 1:he purposes of relinquishment as well as candidate mine-site demarcation. The entire Pioneer Area was divided into 201 blocks of 15" X 15" and nodule abundance in these blocks were calculated from grab data by geostatistical methods. In all, 52,295 photographs were obtained along with 450 hours of video and 1129 km of sub-bottom and side scan data (Sharma et al., 1995).
System Description The deeptow system contains a tow-body, a depressor and connecting cables. The towbody weighs about 600 kg, and comprises 2 still cameras, one video camera, a light source (flash) of 1.3 k joules, altimeter of 100 kHz frequency, a stabilising fin, altitude control mechanism and three electronic modules.