I won't comment on whether a light is needed or not. All I'll say is that we have unintentionally made more than one dinghy trip back to the boat at night without a flashlight. I wasn't worried much about us seeing things as we could see pretty well and we took it nice and slow. What I was worried about though is people not seeing us - especially the people that feel the need to run their dinghy full speed in the mooring field at night. So, my only advice, presuming you intend to use a light, is to make sure you don't forget it when you come in to shore since it will often be light when you are heading in but will turn dark while you are earring dinner.