Hi Wolfgang

Something like this once happened while Atica was on the hard (and I was 5200 miles away!). Of course the usual suspects were all checked, but no avail.

It turned out it was an alarm that sounded from the bow-thruster area: a high pitch beep, not too loud, every 5 seconds or so.

I was reported it was somehow related to "low-battery”, since the boat had been  unplugged from shore power. As soon as the plug was reconnected, it stopped.

Good luck

Roque

Atica

Amel 54