Saw someone on a canal forum in the UK recently who documented how they'd received a letter addressed simply [Name of Boat] [Name of town they were in a few wee

Saw someone on a canal forum in the UK recently who documented how they'd received a letter addressed simply [Name of Boat] [Name of town they were in a few weeks earlier ] via a combination of a postman and a boater who knew which direction they were headed in. Just as well their boat wasn't called Kingfisher or Meander...