The new TSS 440 has tracking range designed to be up to 50% greater than its predecessor, the TSS 340, which with nearly 200 in use around the world, is one of the most successful products of its kind. It is widely used by the oil, gas, and submarine cable industries to locate and survey pipelines and cables on or below the seabed at water depths of up to 3,000m. Development of the 440 was initiated to create a system that is capable of locating pipes and cables that are buried more deeply or laid in more difficult locations. The principal difficulty overcome by the VT TSS development team was the effect that seawater has upon the pulse-induction technology used by the TSS 340. The pulse-induction technique uses a system mounted on a remotely-operated vehicle (ROV) which flies as low as possible over the seabed. Powerful electromagnetic pulses generated by the TSS 340 pass through the seafloor and, on reaching a metallic object, cause electrical eddy currents to be generated within it. These currents create a small electrical discharge that the 340 measures and uses to compute the depth and position of the pipe or cable. It was noted, however, that it was not possible to increase the range of the 340 simply by increasing its power output. This is partly due to the physics of pulse induction which demand a ten-fold increase in voltage output to achieve a doubling of detection range. This problem is made worse by the mildly-conductive effect of seawater which also causes eddy currents to be generated within the water itself. These could be calculated for elimination but for the variations in water conductivity caused by changes in the height at which the ROV flies above the seabed. Variations in seawater temperature and depth also affect its conductivity and make its effect during a survey largely unpredictable. A new mathematical technique has consequently been developed at VT TSS following experiments performed to study the rate at which eddy currents decay in seawater. By developing a new calibration process for the 440 and by exploiting the difference in electrical response from the target and the surrounding water, it was possible for the VT TSS team to develop an algorithm that largely overcomes the problem. Depending on the size and shape of the target, the new tracker offers detection ranges 30-50% greater than the previous model. The increased range means that it can also deal with the potential errors that arise when a cable is in an open trench or passing through a rock berm, and the new system is expected to attract world-wide interest. Significant practical help in the development of the TSS 440 was provided by Statoil, DeepOcean, and Global Marine Systems which assisted with user input and the important sea trials