Re: Without an accurate watch
"It all depends on how precisely you need to know your position of course.". Indeed, If I still remember Slocum bought an old clock, boiled it in oil, and claimed there was no minute finger. Some claim it was his way to shove a minute this way or that way is not that important when there is plenty of water around you. There are radio stations just for giving the time signal, so with a short way radio and preferable a stop watch you could do well even without a time-peace. I do write with hand on experience.
Coat with old-fashioned knife screwdriver and some coins.