VHF alarm mystery

[10PoundHammer]

Three or four times now I have returned to my boat (we live out of town) and found the VHF on. Too often to have accidentally left it on.

Not a big deal except that today (Sunday) I got a call from the marina saying an alarm was sounding - no idea what it was - so I had to call the emergency number and ask the boat minder to head over and find out what was going on.

This is the first time the alarm has sounded, although I've noticed it beeps when the power is turned on if it's not subsequently "cleared." Weird.

I supposed I could remove the fuse when we're not there, but there must be a cause or reason.

Has this happened to anyone else? Any suggestions as to what causes it? Or more importantly how to fix it?

tx TPH

 

[Pilotnavigator]

A dsc emergency or mayday will cause the garmin to turn on and sound alarm. This surprised me a few times last summer. Only way I know is to hit the main power or at least trip the fuse to the radio.

 

[Red Raven]

This happened to me several times though it only happens if the radio is left on. What I have determined is the alarm is the DSC radio warning that it has no GPS coordinates. It has none because the rest of the instruments are turned off including the NMEA bus. I'm not sure why the radio is not on a the GPS or NMEA breaker so this wouldn't happen. Bottom line is I double check to make sure the radio is off when I leave the boat. Also, this will not happen if I turn off the house battery.

Curt

 

[Pilotnavigator]

That is one alarm, after a set time without gps data the radio will sound an alarm. This only happens if the radio is on and th plotter is off. The radio will also wake up even if off, as long as there is power to it when it receives a coast guard emergency message like a mayday. No way that I know of to stop this other than disconnect the power to the radio. Your u can check this by clamping a meter to the power line at the radio when off. It still draws current. It is off but still listening for some messages.

 

[knotflying]

On my boat if the house switch is off and I turn it back on the VHF and the autopilot display turn on automatically. Have you inadvertently turned the house bank off and then on again?

 

[Pilotnavigator]

If there is power to the radio, that means you turned it off by pressing and holding the PWR 16/9 button, then the radio will wake up if it detects a dsc emergency, it will sound an alarm to alert you to accept the alarm and hear the broadcast. Again this happened twice for,the first time since owning the boat last summer when there seemed to be an extraordinary number of mayday events up our way. Only way to stop it is to kill the power to the radio. The battery switch will do it. But if you are trying to run the fridge while away you may have to put in a separate switch just for the radio. In summary turning off the radio is like when I turn off my Samsung tv. It is still on and while it is off it downloads updates!