In addition to the farmland that populated Old Mans, the town's trees provided much of the wood for the shipbuilding trade centered in neighboring Port Jefferson. A shipyard existed in Old Mans for a time, but this was moved to the naturally deeper harbor of Port Jefferson. Riggers, sail-makers, ship carpenters and others lived in Mount Sinai and commuted to Port Jefferson. Grist mills were located somewhere along Pipe Stave Hollow and Crystal Brook Hollow roads. Records indicate that a number of windmills were located on the hills overlooking the harbor.