Yes, it’s a useful piece of paper to have as an aide memoir for navigation marks, distress signals etc.
No, it won't make your boat 'legal' in French waters; and there's the grey area.
The EU has spent millions of the taxpayers (your) money coming up with the Recreational Craft Directive, which was meant to provide accountability for design, construction and usage standards. Kayaks were rightly excluded from this directive, as it was aimed at sailing yachts and motor boats which is why you come up with daft statements like the climbing back in mentioned above. The FFCK (frog BCU) notes on the interpretation of this particular point, basically say that although a practised person with a paddle float could re-mount in this manor, the very core of sea kayaking is helping one another, and therefore the way they would expect you to re-enter a boat would be with support from within the group. This now leads to the situation as to whether you are testing the boat, or the paddler??
In the UK, you just jump in your boat and go paddling; end of (legally).
In France, although the RCD still applies (and excludes kayaks), they made it a condition of going past 300 metres from a shore that the boat should comply with Cat C, which is a bit like moving the goalposts. All is not lost however, as if your boat complies with the rules from another member state, then it will be allowed in their waters. This is the paradox however, as although your boat may be legal here, you can't actually use it. In most cases, being presented with a foreign bit of paper will put off all but the most vicious Affaires Maritime inspection, but the problem is that they can't get their heads round the concept that there isn't a small army of civil servants issuing every kayak with a bit of paper (again, at the taxpayers expense) in the UK.
Add to this, that the rules were changed in April this year, and that most of the AFMAR bunch haven’t even seen a sea kayak, let alone know the rules for it and it starts to get funny. I though for a laugh I would get a piece of paper for my 25 year old Anas Acuta, and duly went to see my local AFMAR bod last week. First of all she insisted that I had plans of the boat, and wasn't going to be swayed by the fact that it was probably in the head of someone in West Greenland, handed down from generation to generation. She also wanted sales paperwork, certificate of conformity (despite the fact it was built before the RCD was even thought of). Her solution was an inspection by Lloyds or suchlike costing x thousand. Failing that, her helpful advice was that I may as well chuck it the bin. I’ve since got the relevant forms from the FFCK website, and plan to brighten up her day some time next week.
So, whilst the sticker is a legal requirement on a French boat, I would actually avoid putting it on a UK boat, as in the event of an inspection it might be deemed that you have tried to comply with French regs and failed, where as without it you can just stick to the “it’s a UK boat” line in you best home counties accent.
And yes; you can’t paddle at night here. A problem that causes me sleepless nights at lease 3 times a week as I paddle home under the moon’s… and harbour master’s watchful gaze….. ;-)
Rules; Great, but I couldn't eat a whole plate of them....