I have a file on board that contains the following paperwork:
Bill of sale and other related boat ownership paperwork
Radio licences, fixed and mobile
Life raft information
EPIRB - Personal Location Beacon registration details
I've also got a set of certificates and membership cards:
Yacht Master Offshore certificate
All this critical info is summarised on a laminated sheet for quick reference as per the picture on the right.
I spell my boats name and my call sign using the phonetic alphabet that we all know and love. I do actually know the phonetic alphabet, but there is nothing like a bumpy sea and a nervous situation to make you forget it at the critical moment when in yacht masterly communication with the coast guard. They frequently ask you to spell your boat name and nothing would be more embarrassing than to fumble around and say "Right yes, PRINCIPIA, I spell, Papa, err, Romulus, no, Remus, um, oh yes sorry, I meant Romeo, Indian, N, what's N?, damn, erm, Nautilus, no, ah, I remember, November" and so on and so forth.
So my laminate has details about the boat, then details about me and then details about my venture. I'll have two of these knocking about, one always on the chart table.
I also have all the relevant manuals for the various bits of equipment on the boat.
I have ensured that details as registered with the authorities are all up to date. This includes:
CG66. Search and Rescue of HM Coastguard operate this scheme and while it is optional, you'd be mad not to register. You provide full details of your boat, contacts and emergency equipment so that, in an emergency they know exactly who/what they are dealing with. Web site is https://mcanet.mcga.gov.uk/public/cg66
PLB: I have decided to carry a Personal Location Beacon and this needs to be registered with the UK Distress & Security Beacon Registry. Again, you give lots of detail including your CG66 reference and all this is joined up by them. Web site is https://www.gov.uk/maritime-safety-weather-and-navigation/register-406-mhz-beacons
Radio licences. Again, you can check and update your details on line at https://services.ofcom.org.uk
If you buy a life raft and/or a EPIRB/PLB then make sure you register it with the manufacturer as it can extend the warranty and you'll probably get a reminder when servicing is due.