Furuno SC70 Satellite Compass with 0.4-degree Heading (No Cable)

The SC70 is Furuno's commercial-grade satellite compass, designed for vessels that need true heading accuracy down to 0.4 degrees for autopilot, radar / ARPA, scanning sonar, current indicator, chartplotter, ECDIS, and other heading-driven navigation systems. It's the part of the helm that owners often don't realize they need until a magnetic compass swings under a buoy in a current or a fluxgate compass goes off after a magnetic disturbance, both situations the satellite compass simply doesn't experience because it derives heading from satellite signals rather than from the Earth's magnetic field.

Multi-GNSS reception is the architectural foundation. The SC70 receives GPS (US), Galileo (EU), and GLONASS (Russia) satellite constellations simultaneously, plus SBAS augmentation from EGNOS (Europe), WAAS (North America), and MSAS (Japan). Using multiple constellations eliminates the problem of poor satellite geometry in any single constellation, the compass always has enough visible satellites for clean fix and heading data even in high latitudes, urban canyons, or near tall offshore structures that would block parts of the sky.

The data set the SC70 outputs goes far beyond heading. GPS position (latitude/longitude), Speed Over Ground (SOG), Course Over Ground (COG), and Rate Of Turn (ROT) are the standard navigation outputs. The 3-axis speed measurement, bow, stern, and longitudinal velocities, is the differentiator for berthing and dynamic positioning operations. When you're maneuvering into a slip with a current pushing the bow one direction and a wind pushing the stern the other, the SC70 reports how fast each end of the boat is actually moving, which is the data the joystick control system needs to drive thrusters and engines for a clean docking. Precision pitch and roll data is also output in analog and digital formats for sonar stabilization and vessel attitude systems.

Heading accuracy is specified at 0.4 degrees, which is the accuracy class that radar/ARPA, scanning sonar, and ECDIS systems need to function correctly. A traditional magnetic compass with proper deviation correction is typically accurate to 1-2 degrees, a fluxgate compass to 1 degree under good conditions, and a GPS-derived heading to 5+ degrees at low speeds (because GPS-COG only equates to heading when the boat is moving in a straight line at speed). The SC70 maintains 0.4-degree heading accuracy at zero boat speed, which is the regime where every other heading source falls apart.

Response speed (follow-up rate) is 40 degrees per second, which is twice the IMO high-speed craft requirement of 20 degrees per second. In practice that means the compass keeps up with the most aggressive maneuver any recreational or commercial vessel is likely to perform, including emergency evasive turns and dynamic-positioning hold corrections. There's no lag where the autopilot or radar overlay drifts off the actual heading.

IMO type-approvals are the credibility marker for commercial work. The SC70 is type-approved as a Transmitting Heading Device (THD), a GPS receiver, and a Rate-Of-Turn Indicator (ROTI), and complies with the relevant IEC and ISO standards. Commercial and pilot-vessel installations that need certified heading data for regulatory or insurance reasons can install the SC70 directly without searching for additional certified equipment.

The hardware architecture is three components: the SC701 junction box (the central interconnect and data switch), the SC702 display unit (heading and status display at the helm), and the SC703 antenna unit (the GNSS receiver plus internal angular rate and accelerometer sensors mounted on the radar mast or arch). All three ship with this kit. The antenna cable that runs between the SC703 and the SC701 is sold separately, sized to the actual installation distance. For owners retrofitting from an older Furuno SC-50, SC-55, SC-60, SC-110, or SC-120 satellite compass, the existing antenna cabling carries forward with the optional LAN_CNV adapter kit, which is a significant cost saving on the retrofit.

Maintenance is zero. No moving parts, no gyroscope to warm up, no fluxgate sensor to recalibrate after every magnetic disturbance. The SC70 simply needs power and the antenna cable run, and the compass is online with 0.4-degree heading accuracy for the life of the vessel. Power-up time is 90 seconds typical from cold start. Compare that to gyrocompasses that need hours to spin up to operating speed.

What's in the box. The SC701 junction box, the SC702 display unit, the SC703 antenna unit with internal sensors, mounting hardware, and the documentation pack. The antenna cable between SC703 and SC701 is sold separately. The LAN_CNV retrofit kit (for owners reusing old SC-series cable) is sold separately.