What do you do when your furl sails?

It means to roll them up & tie them to the spars (or yardarms, as the case may be).

Stealth: At night, they are more difficult to see.

Sails catch the wind which propels the boat forward2nd Answereer says:Previous answerer has been tricked by a trick question:IN REALITY the wind foils around the the sail and PULLS the boat forward....

Strictly speaking, a boat's sails serve to catch the wind, propelling the boat forward. They can be adjusted in a number of ways using things like sheets, halyards, topping lifts, cunninghams, and...

Britiain