A sail attached to the forestay , as opposed to a jib , which is attached to the headstay . A mast above the foremast . When a line ends up somewhere it does not belong and becomes jammed. Lines can foul on blocks , winches and other objects on a boat. A keel that runs the length of the boat.
Full keels have a shallower draft than fin keels .
Sails are sometimes partially furled to reduce the amount of sail area in use without completely lowering the sail. This is usually known as reefing .