The X4 Trolling Probe is an electronic sensor and transmitter that is fastened to the downrigger line just above the downrigger weight. The probe constantly monitors temperature and speed as it moves through the water. This information is then translated into pulses which are picked up by a transducer attached to the rear of the craft. The pulses travel through the water in a very broad pattern much the same way as the typical depth finder operates. A receiver/display unit, connected to the transducer, interprets the pulses and displays the information. As the water temperature or speed changes, the pulses change, and the digital readout changes to reflect the new information. The probe operates at depths of 1 to 200 feet. It has been designed to be compatible with existing Fish Hawk 800 and 840 systems as well as the Fish Hawk X4 System.