The NAVIKNOT Multisensor Speed Log Series is a new generation in a long line of Sperry Marine speed logs. The 350, 450 and 600 series offer unlimited flexibility and have been designed for all types and sizes of vessels.
The NAVIKNOT Multisensor Speed Log Series features two different-sized Control and Display Units (CDU) each with a large color TFT display and utilizes satellite-based technology (GPS) in addition to the traditional Doppler and electromagnetic sensors to provide the user with high-accuracy displays of dual-axis ground speed and/or single-axis water speed.
The NAVIKNOT Multisensor Speed Log Series is a new generation in a long line of successful Northrop Grumman Sperry Marine speed logs. The 350, 450 and 600 series offer unlimited flexibility and have been designed with the most modern computer tools for application on all types and sizes of vessels including cruise ships, container ships, tankers, megayachts and a wide variety of other crafts, both new build, and retrofit.
Flexible and Innovative
The speed log measurement capability at slow speed is vital for precise docking of tankers to oil loading and unloading facilities, as well as safe navigation in narrow channels or straits. Operation at high speed assists economical cruising in open seas. While retaining the measurement accuracy the time for installation and space required for installation will be reduced.
Control and Display Units
The innovative NAVIKNOT Multisensor Speed Log Series features two different-sized Control and Display Units (CDU) each with a large color TFT display and utilizes satellite-based technology (GPS) in addition to the traditional Doppler and Electromagnetic Sensors to provide the user with high-accuracy displays of dual-axis ground speed and/or single-axis water speed.
Electromagnetic Sensor (Single-Axis Water Speed)
The electromagnetic sensor houses a coil which, when energized with an AC current, produces a magnetic field around the sensor in the surrounding water. The ship’s motion through the water produces an electrical field perpendicular to the magnetic field and the ship’s motion. The resulting signal is picked up by the sensor electrodes and fed to the preamplifier, where it is converted into a digital format and transmitted to the NAVIKNOT electronics unit.
Doppler Transducer (Single-Axis Water Speed)
The Doppler transducer utilizes the Doppler frequency shift effect to determine the speed of a vessel through the water. The transducer emits high-frequency sound pulses in the fore and aft directions through two transmitter windows. Two receiver windows in the transducer detect the return echo of the sound pulses. A time delay between pulse transmissions ensures that echoes are received from the undisturbed water outside the vessel’s boundary layer. The signals are processed to determine the ship’s fore/aft speed vector. The preamplifier transmits the speed information in a digital format to the NAVIKNOT electronics unit.
Satellite Sensor (Dual-Axis Ground Speed)
The satellite sensor makes use of GPS satellite signals to determine a ship’s longitudinal and transverse ground speeds. Two GPS receivers and three rate gyros integrated in an electronics unit, and a dual antenna unit, determine a vessel’s heading velocity, course, and attitude. While the heading is referenced to the ship’s fore-and-aft line, the velocity and course represent the motion vector, i.e. the magnitude and direction of its motion overground.