boom (jib/main) [R04]: A spar (pole), along the foot of a fore and aft rigged sail, that greatly improves control of the angle and shape of the sail.
boom vang (US) [R05]: A line or piston system on a sailboat used to exert downward force on the boom and thus control the shape of the sail. This is a kicking strap in the UK.
bowsie [R06]: A simple device with three holes used for tensioning lines on a model yacht.
control loop [R10]: A loop of line or wire placed around a mast or boom to help maintain sail shape.
downhaul [R13]: A device used to tighten the luff of a boom-footed sail by pulling downward on a eyelet in the luff of a mainsail above the tack. This is also known as a Cunningham.
eyelet [R14]: A small round hole (metal) in the corners of a sail to thread a string through.
line [R32]: Used on model yachts for things such as sheets and topping lifts.
mainsail (main) [R35]: The largest sail on a sailboat, crucial for propulsion, is attached to the mast and controlled by the main sheet.
mast [R37]: A tall spar, or arrangement of spars, erected vertically or near-vertically on the median line of a ship or boat.
