Bruce,
I have almost always been asked to show a passport on the 4 or so trips I've done to Alderney... (not been for about 5 years though)
Plus, there is (or was) a mandatory requirement to wear a 'Q', (yellow) flag on entry into Alderney.
Double Plus, the Channel Islands are not part of the UK or the EU, and thus, since you are leaving and on return, re-entering the EU, your vessel becomes subject to customs requirements, (though not Immigration ones). That means you need to inform Customs on your return to the UK and the way I read it, it would be advisable to fill in a C1331 form before you leave.
I know most people ignore this and will tell you otherwise….. and I’ve only heard rumours of one case of a fine, travelling from the Channel Islands and entering the EU in France without notifying…. But if you want peace of mind, see here.
http://customs.hmrc.gov.uk/channelsP...ument#P34_2020
If you go straight to France, you just need the stuff Doug said.
I would stongly recomend getting the SSR!
Enjoy
Mike C