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[DG11]Windspeed values incorrect, too low, after some time, especially with more wind
06-10-19, 10:55 AM (This post was last modified: 06-11-19 03:06 PM by Chuck - Raymarine - Moderator.)
Post: #1
[DG11]Windspeed values incorrect, too low, after some time, especially with more wind
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.
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06-12-19, 07:35 AM
Post: #2
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi Koskam,

Thank you for your enquiry.

From your description it sounds like there is an issue with wind data to the itc5

We would suggest a more thorough check of the voltages at the bottom of the mast - there is usually a connection box there ti enable the mast to be unstepped. In particular, the red to Screen should be 8v, the yellow to screen should be between 2.5 to 6v. If this is the case, then the issue is likely the itc-5, if the voltage between the yellow and the screen is low, then this points towards the masthead unit or the mounting block connection at the top of the mast.

Kind regards

Derek
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06-18-19, 03:07 PM
Post: #3
RE: [DG11]Windspeed values incorrect, too low, after some time, espec. with more wind
Hi Derek,

Thanks a lot for your clear response which provided input for further investigation last weekend.

The red to screen voltage is 7.95, so that seems fine. The yellow to screen I measured at the ITC-5 as well as at the connection box below the mast (they are close to each other). Also at the cable from the mast the voltage was quite low and changing all the time, probably because of the pulses. So I used 2 different multi meters. One of them showed values between about 0.3 and 0.6 volt while the other at some moments peeked just above 1.0 volt, but only incidentally. The wind however was quite weak varying between 3 to at the most 6 knots. So it is not clear whether the pulses are too slow to get the voltage high enough or that also under these circumstances the voltage should be higher on a simple multi meter and this points to a problem at the mast top connection or the unit itself, as you pointed out.

I hope you have some further tips to investigate the problem to determine where the problem might be.

Thanks, Regards,
Kees.
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06-21-19, 08:52 AM
Post: #4
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi KosKam,

The masthead voltages sound too low, we suggest remove the unit from the top of the mast and create a short temporary cable to connect it to the itc-5, this link accessed here will help create this test cable.

This will definitely identify the fault.

Regards
Derek
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06-21-19, 01:15 PM (This post was last modified: 06-21-19 01:22 PM by Chuck - Raymarine - Moderator.)
Post: #5
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
I have a similar problem on a system with 3 X I70's, an e95, a P70 and instead of an ITC-5 I have an SR6 and an SPX30. When the wind exceeds 10-15 knots the wind speed often becomes erratic - sometimes showing 60-90 knots. Usually this happens 30-60 minutes into a sail. Then it will calm down for a few minutes and then go up again. I have installed the most recent software and tried reseting one of the I70's. I checked voltages at the pod and red to bare was consistently 7.92 volts at the dock - yellow or green to bare show 3 or 5 volts depending on wind speed and direction, and blue to bare was consistently 1.97 volts. Also I checked continuity and B tp G was 35 ohms on a 200000 ohm setting, Y to G 75 and B to Y 63 - all on 200,000 ohm settings so I don't think there is a short in the mast wire. Finally, I had sent the transponder and pod back to Ray marine and it came back as passed. I'm at a loss as to what to do next - - One hint of potential problem is when the I70 is in a state of showing normal speeds after having shown erratic readings, engaging the autopilot seems to drive the I70 into an erratic state. The boat speed and depth are never impacted. Do you have suggestions?
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06-25-19, 09:12 AM
Post: #6
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi Sogin,

Are you using a conventional Raymarine masthead unit or relying on the Sirius Weatherstation?

When it overreads is this apparent wind or true wind.

The software in the i70s will not have any impact on this - although it is always best advice to enaure all the system is using the latest current software version.

If the fault happens only when the autopilot is driving, this could point towards a power issue, where voltage dips or surges are being reflected in fluctuating voltages in the Autopilolt

regards
Derek
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06-25-19, 09:30 AM (This post was last modified: 06-25-19 09:35 AM by Chuck - Raymarine - Moderator.)
Post: #7
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
When it over reads it occurs on both TWS and AWS. However it also sometimes goes into a state of "0" AWS. This morning it showed normal wind speed readings but within ten minutes showed only "0" wind speed but Wind Direction was correct. Voltages from mast head unit are normal. The SR6 is used to collect SIRIUS weather and provide 6 switch ports. It is not the source of the wind speed. I tried to find a new wind pod this but instead could only find ITC-5 so I ordered one today and hope to install it the day after it arrives - hopefully on Thursday. If that does not resolve the problem then I think we have more serious issues behind my ability to resolve. The batteries are new (as of last year) Firefly's. They have never been below 70% STC and with respect to observations this year, the batteries were always at 95% or better STC. This vessel spends most of its time on shore power but is currently out in the harbor. If we have a voltage problem how can we track down the problem? Are there measurements to be made at the SPX30?
Thank you for responding
Mitch
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06-25-19, 09:53 AM
Post: #8
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi Sogin,

Thanks - so basically the issue is most likely the masthead Tx or the wind pod into which the masthead unit is connected. Replace the wind pod and recheck the voltages again, however, the voltages that you measured suggest there is a problem with the blue to screen cable at least and so you should get the masthead unit down from the top of the mast, and test the masthead unit direct with a short test cable - there is a link in the earlier thread to help make this cable.

regards
Derek
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07-03-19, 03:29 PM
Post: #9
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi Sogin and Derek,

Last week I went by the boat yard who installed the instruments and they exchanged the mast top wind unit with one that worked on a different boat and that one worked. Voltages measured with the multi meter were also clearly higher, between 1.5 and 1.9 volt, so not yet the 2.5-6 volt but clearly different. And as the wind values seemed clearly more reliable, the mast top unit was exchanged multiple times with our problematic one, it was clear the mast top unit was the problem.

So they did send us along the dealer in a nearby town (we could lend the car of the yard owner) and the unit was exchange under warranty with a new one. After installing that it gave the same higher voltages in the 1.5-1.9 range but I suppose that is a multi meter issue.

Now we are experiencing a fine wind meter again with wind values that seem to be according what we experience. ;-)

Unfortunately the AIS 700 unit stopped working but that is something for a different thread, at the moment I am upgrading all network component to the latest software versions to check whether that helps.

Derek, thanks a lot for your help as the voltage measurement helped to indicate the cable of the mast top unit itself was the problem.

Best Regards,
Kees.
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07-04-19, 08:18 AM
Post: #10
RE: [DG11]Windspeed values incorrect, too low, after some time, especially with more wind
Hi Kees,

Great news about the masthead wind, sadly they get a lot of bad press, but work harder than most onboard a boat, the top of a mast is a pretty hostile place, high 'g' forces, rapid movements and high shockloads, they also endure periodic seagull attacks too!
Aside from general maintenance to check the security of the main knurled nut, check for corrosion on the mounting block pins, you also need to consider the mast cable, some mast cables are supported inside the mast, others just hang from the top and so there are potential issues with fatigue too, so the voltage tests will help identify where the issue is more likely to be.

Yep - with the AIS700, please start a new thread, but a good starting point is update all software to the current version and thoroughly check connections, cables, and voltages!

All the best
Derek
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