BACKSTAYS - Long lines or cables, reaching from the rear of the vessel to the mast heads, used to support the mast.

BAILER - A device used in the event water needs to be emptied or bailed from a boat.

BATTEN DOWN - Secure hatches and loose objects both within the hull and on deck.

BEACON - A lighted or unlighted fixed aid to navigation attached directly to the earth’s surface.

BEAM - The greatest width of the marine vessel.

BEARING - The direction of an object expressed either as a true bearing as shown on the chart, or as a bearing relative to the heading of the marine vessel.

BELOW - Beneath the deck.

BERTH - A bed on a yacht, or a space in a port or harbour where a vessel can be tied up.

BIGHT - The part of the rope or line, between the end and the standing part, on which a knot is formed. BILGE - The interior of the hull below the floor boards.

BILGE - The bilge is the compartment at the bottom of the hull of a boat or ship where water collects so that it may be pumped out of the vessel at a later time.

BIMINI - Fabric fastened above the cockpit of a boat to provide protection from weather or the sun.

BITTER END - The last part of a rope or chain.The inboard end of the anchor rode.

BOAT HOOK - A short shaft with a fitting at one end shaped to facilitate use in putting a line over a piling, recovering an object dropped overboard, or in pushing or fending off.

BOOM - A spar used to extend the foot of a sail.

BOOM VANG - A sail control that lets one apply downward tension on the boom, countering the upward tension provided by the mainsail.

BOOT TOP - A painted line that indicates the designed waterline.

BOW - The forward part of a boat.

BOW LINE - A docking line leading from the bow.

BOWLINE - A knot used to form a temporary loop in the end of a line.

BOWSPRIT - A spar projecting from the bow used as an anchor for the forestay and other rigging.

BRAVO - Letter B in the Marine Radio Alphabet.

BRIDGE - The location from which a vessel is operated.

BRIDLE - A line or wire secured at both ends in order to distribute a strain between two points.

BRIGHTWORK - Varnished woodwork and/or polished metal.

BULKHEAD - A vertical partition separating compartments.

BUOY - An anchored float used for marking a position on the water or a hazard or a shoal and for mooring.

BURDENED VESSEL - That vessel which, according to the applicable Navigation Rules, must give way to the privileged vessel. The term has been superseded by the term "give-way".

BY THE BOARD - All that has gone overboard.