Boom vang
Boom
Downhaul
Line
Main (sail)
Mast
Control loop
Bowsie
Eyelet
Mast tang
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.
mast [R37]: A tall spar, or arrangement of spars, erected vertically or near-vertically on the median line of a ship or boat.
