Common: latticed wooden frame over which sail-cloth was fixed to suit strength of the wind. Double shuttered: sails with shutters on both leading and trailing sides of their whips. Patent: sails with shutters capable of automatic adjustment by the striking gear even whilst rotating. Single shuttered: sails with shutters on the trailing edge only. Spring: sails with hinged timber shutters, set before operating the mill, and connected by a spring-loaded lever which allows the shutters to open if struck by a gust of wind.

Southeastern Automated Integrated Libraries

The sailmaker is meant.