My purpose is the same as the life raft principle i.e. I'd rather have maps for any time that 'I have no other choice' scenario than not have the maps and need them. I think there are a lot of marinas that are relatively 'safe' to go into at night but it can still be a real trial to find the guest slip. Especially after a long sail. If I had my way I'd only sail in perfect weather on warm sunny days. The sea and mother nature sometimes don't give me what I want. Maybe I'm not asking nicely enough.