When doing long passages, or hard passages you need to be wary of the ever so common error, ID, 10 T.
Yes an IDIOT can cause so much damage. Just recently I had to fix a fuse in my Nav station. I am very proud of my abilities and have decades of experience working with electronics. However soon after this our AIS started having issues with sending out its position.
Now, it still did send its position but unreliably and our VHF signal seemed poor and often distorted, BUT was still working.
Just recently, fortunately before climbing the mast to clean aerial terminals, I discovered that when I had fixed the fuse I had put the AIS aerial and VHF connections on back the front, i.e. connected aerial to VHF and VHF to Aerial.