Hi,
Should beaches be digitsed as new areas or created from existing coastline boundaries and new line segments as relations. Those that I have checked were not created as relations but do share nodes with the coastline e.g. https://www.openstreetmap.org/edit?editor=potlatch2#map=15/52.3003/-10.0285.
Regards
Just as with other areas, there is no clear rule about when to use traditional areas and when to use multipolygon relations for beaches. Both mapping styles work, and the semantics are the same for both.
Personally, I prefer avoiding relations in those cases. I believe that areas that share nodes with the coastline are easier to understand for inexperienced mappers.