I believe that you do need to code it.
I'm looking at doing something similar next summer - but if you look at the inland wterways coding on the MCA website,
http://www.mcga.gov.uk/c4mca/mcga-gu...qs_iw_code.htm, annex 5 gives guidelines for beachcraft - which sounds like it would cover these sort of activities to get passengers out to the 'big' boat. It also seems to be quite a sensible way forward - not too OTT.
Cheers,
Dylan...