Sonar capability, primarily used to locate objects such as reentry cones which are initially out of camera range, is and integral part of the system. The sonar, in conjunction with a compass attached to the VIT frame, provides primary range and bearing from the VIT frame to the reentry cone. An acoustic beacon can be attached to the VIT frame which allows the ships dynamic positioning system computers to fix the position of the VIT frame relative to the ship. The VIT frame is deployed by latching its guide sleeve around the drill string. The drill string is used as a guide as the VIT is lowered to the sea floor by means of an armored coaxial cable attached to a special winch located in the ships moonpool area.
Power is transmitted down the coaxial cable to operate the underwater lights, camera and sonar.
The TV and sonar signals are then transmitted up the coaxial cable for display and recording on board the ship. The VIT can also be used to precisely locate spudding sites. Once located, the sites can be marked by dropping an identifying marker from the VIT frame itself, via an acoustic release.