I suppose that this is yet another case of rampant Ludditeism...
We have long simply told interested parties that we would be out of touch for an indeterminate period, and that we would get in touch sometime in the future when it suited us and the opportunity was there. We are very firm that we have NO ETA, and that we do not want any notification of authorities because we have not been in touch. This may seem harsh, but it reflects our cruising style, and honestly, it seems to reduce any anxiety on the part of shore based folks. They have no expectations of contact and so don't miss it. Our family and friends have not seemed to object to this practice.
This system was developed after a well meaning friend (and a fellow yottie at that) notified the CG in Hawaii
when we were a few HOURS late on an ETA given by ham radio
several days prior, and at the end of a long ocean passage
(Bora Bora to Hilo). In those days the customs
clearance area was right next to the CG dock
Bay, and we were chastised a bit by the Coasties. Actually, they were pretty understanding and had not undertaken any SAR activities on our account, but it was a lesson for us.
The advent of various satellite
based comms systems makes notification pretty easy, and that is seductive. But then if there is a glitch in the system, all hell breaks loose. The well meaning folks ashore panic... and that includes the supposedly knowledgeable people here on CF (remember Boaties un-needed "rescue"?). So, we will remain mute for routine passages, but have good HF capabilities and the Big Red Button on the EPIRB
for real emergencies. YMMV.