Erratic or dead wind readings? Before you climb the mast or buy a new sensor, a five-minute multimeter test at the instrument will tell you whether the fault is in the transducer, the cable, or the display. Here's how to do it safely.
When to run this test
Run through this check if your wind display shows no wind data, a frozen angle, a stuck or wandering wind speed, or readings that drop out intermittently. It applies to Raymarine analogue wind systems — the ST40, ST60/ST60+, i40, i50 and i60 instruments that use the short-arm or long-arm wind vane. These sensors use a five-conductor connection: red, blue, green, yellow and a bare screen (shield).
What you'll need
- A digital multimeter set to DC volts (use the 20V range if your meter is manual-ranging).
- The wind display connected and powered — the display supplies power to the masthead, so it must be on to test.
- Access to the transducer's terminals at the back of the instrument or at the cable junction.
Safety first: you are working with low-voltage DC only, but take normal care around the electrical panel, and never carry out this test with anyone aloft or working at the masthead.
How the sensor works
The display sends a steady supply voltage up to the masthead. The wind vane returns two directional signals — one for the port side of its travel, one for the starboard side — and a separate wind-speed signal that pulses faster as the cups spin. By measuring each wire against the screen you can see at a glance which part of the circuit has failed.
The test: what to measure
With the display powered on, gently back-probe each terminal (push the meter's positive probe into the rear of the crimp terminal) and put the negative probe on the screen/shield. Measure each in turn:
| Wire → Screen | What it is | Expected reading (DC) |
|---|---|---|
| Red | Masthead power from the display | ~8V, steady |
| Blue | Port directional element | 2–6V, changes as the vane turns |
| Green | Starboard directional element | 2–6V, changes as the vane turns |
| Yellow | Wind-speed signal | 0–5V, rises with speed |
Tip for the speed reading: at anything above a light breeze the meter averages the pulses and won't settle. Do this part by turning the cups slowly by hand, or in very light wind, so you can see the voltage step with each pulse.
Reading the results
- No ~8V on red — the fault is on the display or supply side, not the masthead sensor. Check the display's own power and connections before doing anything aloft.
- Good 8V on red, but a directional or speed wire sits at a constant 0V — likely a break or short in the cable, or a corroded masthead connector.
- A wire stuck at a constant high voltage — often a vane fault, a short in the cable, or water sitting in the masthead plug creating a partial short between pins.
- Directional voltages that don't change as you turn the vane — points to the vane unit itself or its cable rather than the display.
The usual culprits
On older installations the problem is very often water ingress at the masthead plug, a cable chafed through at the spreaders or mast base, or corroded crimp terminals behind the instrument. It's always worth inspecting and cleaning the masthead connector with a magnifier before condemning the sensor — a dab of corrosion is a common and cheap fix.
What to do next
If the test points to the display or supply side, start there. If you have a healthy 8V feed but the vane signals are dead or frozen, the masthead transducer or its cable is the likely cause. We stock the genuine replacement sensors, including the Raymarine RSW Smart Performance short-arm wind transducer and complete wind packs such as the i60 wind pack with short-arm vane.
Not sure what the numbers are telling you? Send us your readings and our team will help you pin down the fault before you spend on parts.
These figures are typical for Raymarine analogue wind vanes and are provided as a general troubleshooting guide. Always confirm the correct values and wiring for your specific instrument against its official Raymarine manual, and if in doubt contact Hudson Marine Electronics or a qualified marine electronics engineer.
