You may well have used, or at least be aware of, the Coastguard CG66 scheme. This was a form you filled in with details of you and your boat, as well as contact numbers of next of kin, and submitted to the MCGA. This provided the Coastguard and rescue services with important information about you and your boat in the event that you got into trouble.
The problem is it's an outdated and very manual system, and the Coastguard have now officially adopted the RYA's SafeTrx mobile app as a replacement. See this article for full details (new window).
You may have already installed the SafeTrx app, but if not there is now even more reason to do so. If you don't have an Android or Apple phone, you can still register all the details of your boat and emergency contacts online here. If you don't have a login you can register for one on that page (RYA membership is not required).