Design and optimization of an efficient overboarding mechanism for the drop/lift automation of an active/passive sonar system in a surface ship

An active/passive sonar system consists of 1) a transmitter towing cable for adjusting the depth of the transmitter towed body, 2) a receiving array for measuring sound waves, 3) a transmitter towed body for transforming sound waves and 4) an array cable for connecting a receiving array to a transmitter towed body. There is a need to develop an automated equipment to drop the active/passive sonar system into the deep sea from the surface ship and then lift it, since this consists of a cable with a length of over 1000m, a transmitter towed body, etc. With the research on the active/passive sonar system, a variety of mechanisms of the overboarding unit suitable for the limited environments have been developed. This paper suggests a new overboarding mechanism which is efficient in operation and maintenance of the sonar system. First, we analyzes the strengths and weaknesses of the existing overboarding mechanisms, and then suggest a new mechanism to improve these problems. For the proposed mechanism, we will treat with a technique to optimize the link length and the actuator length for the mechanism not to interfere in the hull's internal environment, to satisfy work ROM (Range of Motion) and to have good torque-angle properties. Our approach will be helpful for calculating the maximized output torque of the actuator for the actual application of a similar type of the proposed mechanism in practice.