Trimming sails and different circumstances

by Christian Hatton
(Duncan, British Columbia, Canada)

For a while now I have wondered how square rigged ships trim their sails. I have seen in movies 10s of men pulling on long lines is this trimming a square sail? and did they have winches back in those days? And in some movies i have noticed the square sails luff like a spinnaker on a reach like modern ships? how would you know when to stop trimming a square sail? is it like a modern day spinnaker?

Look forward to hearing back

Christian