Threaded Mode | Linear Mode

koskam

Since a few weeks we have a new boat with a new set of Raymarine instruments. The instruments are newly installed and at first everything seemed to work fine.

But having sailed with some more wind it appeared the wind speed started to show incorrect speed values. Especially in gusts the shown wind speed decreased to below 10 knots where the gusts were clearly over 20 knots. So during gusts wind speed decreased instead of increased (sailing to the wind, transducer on mast top in a forward facing position).

Transducer is E22078 connected through an ITC-5 to a i70s display. The display is okay, I have checked it through a multiplexer that converts the values to NMEA readings which drive a repeater able to display these (ICS Nav6, Navtex receiver with repeater functionality).

I have noticed the following symptoms:

- When just arrived at the boat and instruments were switched on, gusts were showing fine, over 30 knots during some showers, while docked.
- Half an hour later wind gusts increased but the meter did not show higher wind speeds than about 15 knots.
- This is the same as experienced during 2 earlier weekends, initially wind speed shows fine but after some time shows incorrect speeds, a clearly lower value than actual wind speed is shown. Switching instruments off and on does not help (as if something has warmed up and does not function correct anymore).
- This resulted in the strange behavior that when sailing a week ago to the wind with increasing wind speed, finally Bft 5 with gusts Bft 6 (reported on VHF), the AWS decreased to 0.0 constantly where TWS became equal to speed through water, 7.0 knots (SOG 6.7). Only when back in our berth there was some wind speed shown again but still only Bft2-3 speeds. I have attached a picture from this situation, wind is shown in the midst of the 3 i70s's.
- I have tested the voltages as described in a different post and those seem okay, although I cannot measure the individual pulses (voltage for wind speed was reported varying between about 2.5-3.5 volt with calm winds, less than 10 knots).
- Of course the transducer 'wheel' is turning around fine, it is new and clearly rotates faster with more wind and it also works fine initially when the instruments are 'cold' started.
- When the ITC-5 is switched on the wind led remains constant lit. The speed and sea temperature transducer led initially is also constantly lit, but after some minutes it changes to a continuous pulse. This is while not sailing, so no speed through water (showing up as 0.0). This behavior is repeated when switching off and on again. Does this blinking indicate a problem or is this normal when not sailing?
- Last observation from yesterday was with very calm winds, varying between 2- 4 knots, there were some short 'flashes' of wind speeds between 10-15 knots while there clearly was no wind increase in reality. I have recorded this in a short film with my phone as this was such strange behavior the other way around.
- Wind angle is showing fine all the time.

What can I do to further research this problem? The wind transducer seems to work fine when we freshly arrive at the boat and switch the instruments on but after some time the problem comes up, what can cause this. ITC-5 is on software version 1.12 and I cannot find anything that sounds alike this problem.