sailing vessel in and out of port, navigating it to its destination, and securing it at anchor or alongside a dock. Important aspects of seamanship include employing a common language aboard a sailing craft and the management of lines that control the sails and rigging. Nautical terms Nautical terms for elements of a vessel: starboard (right-hand side), port or larboard (left-hand side), forward or fore (frontward), aft or abaft (rearward), bow (forward part of the hull), stern (aft part of the hull), beam (the widest part). Spars, supporting sails, include masts, booms, yards, gaffs and poles. Moveable lines that control sails or other equipment are known collectively as a vessel's running rigging. Lines that raise sails are called halyards while those that strike them are called downhauls. Lines that adjust (trim) the sails are called sheets. These are often referred to using the name of the sail they control (such as main sheet or jib sheet). Guys are used to control the ends of other spars such as spinnaker poles. Lines used to tie a boat up when alongside are called docklines, docking cables or mooring warps. A rode is what attaches an anchored boat to its anchor. Management of lines The following knots are commonly used to handle ropes and lines on sailing craft: Bowline – forms a loop at the end of a rope or line, useful for lassoing a piling. Cleat hitch – affixes a line to a cleat, used with docking lines. Clove hitch – two half hitches, used for tying onto a post or hanging a fender. Figure-eight – a stopper knot, prevents a line from sliding past the opening in a fitting. Rolling hitch – a friction hitch onto a line or a spar that pulls in one direction and slides in the other. Sheet bend – joins two rope ends, when improvising a longer line. Reef knot or square knot – used for reefing or storing a sail by tying two ends of a line together. Lines and halyards are typically coiled neatly for stowage and reuse. Sail physics The physics of sailing arises from a balance of forces between the wind powering the sailing craft as it passes over its sails and the resistance by the sailing craft against being blown off course, which is provided in the water by the keel, rudder, underwater foils and other elements of the underbody of