1-10 DATASONICSVolume I System Manual June 1998provide the optimum beam pattern for tracking the tow vehicle with anacoustic positioning system. The optional pressure sensor is contained withinthe end cap and is exposed to ambient pressure through a port on the rim ofthe end cap.The nose is attached to the forward end of a pressure housing, theelectronics housing, which contains the sonar electronics. An end cap bothseals the opposite end of the housing and attaches to another housing, thesonar transducer housing, which is free flooding and contains the sonartransducers. The nose and end cap are secured to the electronics housingwith a closure bolt in the nose. The electronics housing also contains thevehicle’s tow point, and the sonar transducer housing contains the vehicle’stail fin.The tow vehicle’s towing arm, which is designed for rapid attachment anddetachment, contains a shear pin release mechanism, which is designed tocause the towing arm to break away from the tow point should a collisionoccur or should the tow vehicle become snagged. However, one end of arecovery cable is attached to the towing arm. The cable runs back along thetop of the vehicle to its stern. Should an obstruction cause the tension on thetowing arm to exceed 200 lbs, the towing arm will break away and the towvehicle will cartwheel one-half of a revolution, with the nose movingdownward and then backward, clearing the tow vehicle from the obstruction.This is shown in Figure 1-3. As the recovery cable remains attached, the towvehicle can be safely recovered. The tail fin will also break away should itcollide with an obstruction—and it is easily replaced.Sidescan Sonar Transducer ArraysThe sidescan sonar, which operates in the 190 to 210 kHz band, utilizes twotransducer line arrays that are installed in the free flooding transducerhousing. The arrays are aligned end to end, with one along each side of thetow vehicle. This arrangement provides a one-way horizontal beam width of1° and a vertical beam width of 50°. In addition, the down-look angle of eachtransducer array is adjustable from 0° to 20° in 10° increments.
