GENERAL SCHEME ANALYSIS OF THE LIGHTWEIGHT ACOUSTIC DEEP-TOW SYSTEM FOR GAS HYDRATE EXPLORATION

This paper presents the general scheme of a lightweight acoustic deep-tow system for gas hydrate exploration. The selection of the towing mode is one of the key problems. The gravity type of towing system is easily being operated with poor stability, and the weak positive buoyancy type of towing system is of good stability, but complex in operation. This paper demonstrates the performance of the two types of acoustic deep-tow system, and analyzes the ways to enhance the stability of the gravity type of deep-tow system. The results show that the pitch stability of the gravity type of towing system is much behind the weak positive buoyancy type of towing system, and the measures being taken to improve the stability is not effective. Secondly, in this paper we discussed the other methods, such as bathymetric sidescan sonar, sidescan sonar, multi-beam bathymetric sonar, subbottom profiler, acoustic doppler velocity log and other sonars, which are usually equipped in deep-tow systems, and have obtained the quasi-quantitative requirements for the stability of the towing platform. By consideration of platform stability, requirements for supporting equipment, development experience and cost factors, we recommended the weak positive buoyancy type of towing system for better detection results, and the overall design of the system is presented.