[CA] [CA11] Wind speed jumping

[YachtAlia]

We have an issue with the wind speed giving irregular readings.

We have a network on the boat with 2 x e165 displays, 8 x i70 displays and autopilot, AIS, VHF all raymarine and 2 Garmin repeater displays too.

The wind information is from a E22078 wind transducer wired through a itc-5 converter.

The cable has a join at the base of the mast and another 4 meter section to the itc-5.

I have recently replaced the Wind transducer, the mast head socket and the cable due to weather/corrosion/age damage.

The wind direction is fine.

The wind speed reads fine for 50% of the time but every 4-6 seconds spikes to 60-80 knots of wind, then returns to normal. This only occurs when we are at sea and the boat is moving/rocking. In the marina or flat seas it reads fine. The cable is secure in the boat and in trunking in the mast so not flapping about. The boat is a large catamaran so does not move wildly and I cannot believe the mast moves at 50 knots to create extra wind.

I can only guess that current is induced in the cable when we move about, but should the shielding not prevent this?

I have only recently joined the boat so do not know how it behaved before.

Any ideas appreciated.