Wind Anenometer Gone Wild

[Benny]

Finally launched the boat and motored her across Lake Ontario to Toronto Island to her new berth - no wind until Toronto Harbour just approaching the marina when a few good gusts piped up. All of a sudden my Raymarine ST40 wind display alarms started beeping and it showed 30 kinots of wind and climbing to 80! The gusts may have been 20 to 25 so I shut the alarm off but it went off again and the display was reading all over the place between 20 knots and 60 knots of wind. Couldnn't figure itr but docked the boat and squared away and shut down my elecgtronics. The next day, I noticed on the electrical panel that the three mast lights - steaming, anchor and fordeck (spreader) indicator led's beside the toggle switches were glowing faintly. Thought I might have a short so i started by tracing all wires to the foot of the mast and no problem. Took apart the thru-deck fittings and thought this solved the problem because the faint lights went out. Replaced it - the lights went back on when i connected it. OK then I circuit tested the wires coming fron the mast and found a slight current in each but when I disconnected them one by one , the other two would stay lit. There was also no problem when I turned each light on - they lit up on the mast as they should with no breaker trip.

I spent all day trying different configurations and finally it dawned on me. The anenometer while spinning is sending a signal which is a low current to the display and it must have somehow got shorted together with the common ground wire for the three mast lights at the top of the mast with the anchor light ground wire - which is connected to the other grounds for the other two lights and then runs as a single wire to the thru deck connector. This then sent a small current back to the circuits through the lights and to the toggle breaker switches which powered the indicator LED lights but only faintly.

This is what I think is happening. Before I risk life and limb going to the top of the mast, does anyone else think this might be the problem. BTW I disconnected all batteries and shore power so there was no currwent in the panel from any source and the LED's were still glowing. It's either as I think or the boat is haunted. Any thoughts on my analysis?

Thanks for the help, Randy

[hellosailor]

Randy, did you cheat and try to double up or gang some of the wires? The Raymarines that I'm familiar with use their own dedicated multi-conductor line coming down from the anemometer, there is no way it can interact with the masthead lighting unless something has been shorted out. Which would mean a trip upstairs to find out what was pinched or chafed.

IIRC it is a two-conductor shielded wire pair, like common microphone or PA system wiring, with no connection to anything except the Raymarine instrument bundle at the nav station.

[GordMay]

Did the (3) faint mast light LEDs go dark, when you disconnected the anemometer wires?
As Hello’ notes, the anemometer cable should be shielded.

Is the common Negative Return wire upsized from the (3) Positive Light feeds? Although this has nothing to do with your current problem (pun intended), it illustrates one of the problems with common negatives (another being the loss of multiple circuits when 1 wire fails).

[Benny]

Thanks for the replies Hellosailor and Gord.

The raymarine cable is isolated from the masthead light wires except they exit the same hole at the top of the mast and I think they may be shorted by a screw tip or the anenometer plate has some movement which wore through the sheilding of both the ground wire and the anenometer cable and is connecting them electrically.

The faint lights still appear even when the anenometer cable is disconected from the thru deck fitting at the foot of the mast. This led me to think that the anenometer cable has shorted into the ground of the masthead light wire and is carrying a small current due to the rotation of the anenometer through this ground wire which is common to the three lights on the mast. Unfortunately, I used a common ground for the mast lights - separate from the anenometer cable - duh - but it was already in place and in my rush to get the boat in the water, decided not to change the wiring this year - stupid I know because it is always the thing you choose not to do because it will be OK for now that bites you in the arse. Also because the readings of the wind display are going crazy.

Anyhow I would like to know if anyone thinks this could happen with the anenometer sending a current through the ground for the lights if the two got shorted together somehow. Also it has not been calm but later this week if the anenometer is not spinning, I will know for sure if the LED's don't glow.

Thanks for the help, Randy

[Vasco]

Randy,

If you are in Toronto Island there are antennas there (don't know if it's a radio station or what) that makes led's glow and also screws up all the electronic instruments. Whenever we go in the cut from the harbour west of Toronto Island Marina we switch the electronics off as all we get is error messages. It's in the air!! I guess you're lucky your hair isn't standing up. Check with your neighbours in the marina.

[hellosailor]

Rick's idea (RFI) would be a neat answer. But if the problem is a short, and not RFI, I'd be concerned that turning on one of those masthead lights might put too much voltage, or reverse voltage, into the anemometer--which could blow it out.

Something to check & look into before using those masthead lights.

[Benny]

Rick - Wow - that's exactly where it happened but only the wind display went crazy and only the three LED's on the mast lights are glowing. I'll check it out later this week when i turn on all the electronics and see what happens. Due to the Island airport being right there, I wonder if they have any problems with instruments or maybe the interference originates there for security reasons.

Thanks for the info, Randy

[Benny]

Thanks for the warning Hellosailor but it's too late for that - hopefully no damage is done.

Regards, Randy

[Vasco]

Randy,

The antennas are strung on Centre Island in the swamp by the school. If you are in a slip in the south part of the marina I would think they are affecting you. Best way to check is to take the boat out into the harbour a ways. The glowing should stop. One last word of advice... wear your lead shorts when in the marina.

[svHyLyte]

The effects of radiation from nearby radars can be dramatic. Rather longer ago than I care to recall we had an experience on a return trip from Catalina Island to Long Beach. While blasting along on a very broad port reach in pretty strong air with our ST4000 steering, the yacht suddenly made a 90 deg right turn and gybed us into a hove-to position on starboard before I could disengage the autopilot clutch. Fortunately we were undamaged. After collecting ourselves, gybing back to port and getting back under way, not two minutes after we re-engaged the autopilot, it again suddenly tried to turn us to starboard, although I was able to release the clutch and keep us on track. A few minutes later, while on the top of a wave, we observed a US Navy guided missle frigate off our starboard bows within a mile or two. With the autopilot still enabled--but the clutch disengaged--I realized that every time we rose over a wave-top the drive motor spun like crazy, but then subsided once we were down the back into the hollow.

This action continued for some time, until the ship was hull down on the horizon, after which the autopilot resumed its normal dependable operation. Later, at our yacht club, a friend commented that he'd had a similar experience with his system and that whenever sailing near Angles Gate, if he saw a Navy ship heading in or out, he belayed his autopilot as the ship's radars seemd to have an influence on their operation. We never had another experience like that but then, we never had the autopilot on when we encountered another Navy ship!

Cheers,

sv HyLyte

[Benny]

Rick - lead shorts - that's funny - but not necessary - had the BIG V years ago -. Yes I'm going over on Wednesday and will take the boat out into the harbour and see what happens.

Regards, Randy

[DeepFrz]

RFI makes more sense than a short from your wind anemometer to ground. Your LED's are not, or should not be connected between the lights and ground, rather they should be connected across the circuit at your breaker panel. However, as you have found out a common ground wire makes troubleshooting more complicated.

You may want to check the shielding on your wind instrument cable though to see if the RFI is getting in through a break in the shielding.

[senormechanico]

RFI is very possible, although my first vote is for a bad ground connection.

Steve B.