I could not find a Hunter 37 manual with a list of lines. My recommendation is to attach a tag line and remove it and replace with same length assuming you are happy with that length. That way you can ensure you do not buy extra unuseable length. That is what I do when replacing my mainsheet. Hunter specifies 11 mm (7/16 inch) diameter Samson XLS (or equivalent) for the mainsheet for your boat size.I need to replace the mainsheet on my Marlow Hunter 37. Any suggestions on diameter and type of line?