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Stowe Marine Gravity Switch

\Analogue Boat Speed

Dual Display

Wind Display

Quad Display

Compass Display

Digital Boat Speed

Magnified Wind Angle

NMEA gps repeater

clubhouse display

rudder display

loadcell display

 Download Installation Sheets     Download Demo Software

Gravity Change Over Switch

NMEA 2000 Version is now available. The Tack Change Over Switch allows two NMEA 2000, Simnet, Seatalk NG, or CANbus 'Smart' sensors such as the Airmar DST800 on one instrument system or display. Boat Speed and/or Depth PGN's are automatically routed from either the Port or Starboard transducer or boat speed sensor and output as a single source to the connected instruments. If the apparent wind information is available on the bus then the Tack COS will use this as priority for deciding which tack the vessel is on. If no wind PGN is available then the Tack COS has its own gravity change over switch built in. Installation couldn't be easier. Simply screw to the bulkhead and connect to the bus using the supplied NMEA 2000 connection.

The standard version Stowe Gravity Switch has change over contacts for use with more traditional sensors. However, it is no ordinary gravity change over switch. Running intelligent algorithms, the switch avoids unnecessary switching which causes inaccurate boat speed readings, delayed depth readings and early switch contact failure. With an inbuilt microcontroller, this switch prevents the unwanted switching between transducers whilst sailing in light breeze, downwind, motoring or while the boat is at rest.

The standard version works on gravity alone to calculate which transducer to use. There is also an NMEA version that takes NMEA wind angle data to calculate which tack the boat is on, but still using change overcontacts to switch traditional sensors. This version is especially useful in catamarans or other craft with very small heel angle.

These Stowe products have been designed to work with almost any manufactures speed or depth instruments.



Voltage Input 10 to 32 VDC

Current consumption 50 mA


 Rugged ABS case

 Silicone Gasket


105mm x 80mm x 55mm


Operating Temperature -25 to 75 C

Enclosure Rating IP67

CE approved

Design subject to change without notice

(c) 2007 Stowe Marine Limited