A GPS speedometer that shows true speed over ground and a compass heading on a single 85mm LCD display, with no sender, paddlewheel or through-hull fitting to install. Because it reads position from satellites, the speed isn't affected by water flow, tide or wheel size — it's the same accurate reading on the water or on the road.

Speed can be shown in knots, mph or km/h (0–99). It's especially useful where you need a dependable reading at low speed: on rivers and in speed-restricted zones it stays accurate down to around 1 knot, where a paddlewheel log struggles.

• 85mm (3⅜") diameter — fits a standard large-gauge opening
• Speed (SOG) and compass heading (COG) on a clear backlit LCD
• Units switchable between knots, mph and km/h
• High-sensitivity GPS aerial included — plugs straight into the gauge
• 12V, with a dropping resistor included for 24V systems
• IP56 — protected against dust and spray
• Choice of black or white face, with a stainless, black or white bezel

The aerial needs a clear view of the sky — mount it outside, or inside behind the windscreen — and plugs into the socket on the back; don't cut the cable. On power-up it takes about a minute to find the satellites, and because the reading comes from movement, the speed and compass only update once you're under way.

The display is for reference only and should not be used as your sole means of navigation.

Running on 24V? Fit the included resistor, or feed the dashboard from a voltage regulator for a cleaner, steadier supply (why this matters →). Prefer a traditional dial? See the analogue GPS speedometer →, or browse all speed gauges →.