A Complete Glossary of Common Nautical Terminology A-C

Nautical terminology has been used for centuries as a universal language among seafarers. Many nautical terms and expressions entered the English language during the 16th and 17th centuries, as English became the dominant seafaring language. The Royal Navy, in particular, played a crucial role in developing and standardising nautical terminology, with its official publications and manuals on seamanship and navigation.

As a boat or ship owner, it is essential to understand the nautical terminology as it provides safety whilst out at sea, helps with navigation of the water and can assist with communicating with other seafarers on your journeys. Although this language may be older than many ships on the water today, it consistently evolves as new technologies and practices develop. So as a marine chandlery online, we are helping you out with a complete glossary of nautical terms we think you may find helpful during your adventures at sea.

Nautical Terms A

Abaft – This is the back end of the boat. For example, “the lifeboats were located abaft the ship.”

Aback – A sail position with the wind striking on its leeward side.

Aft – Around or near the back of the vessel.

Abeam – At a right angle to the boat’s centre line.

Able seaman – A merchant seaman able to perform all necessary duties on a vessel, often used to refer to junior rank in some naval professions.

Aboard – On or in the vessel.

About – To change direction or course, often by tacking, but is also known within drills for sailors. For example, a drill sergeant may command “about turn, ” meaning the crew must make a swift 180° turn in the opposing direction.

Above board – On or above the main deck. Colloquially it can mean in plain sight.

Adrift – Afloat on the water without attachment to the shore or seabed. It can also mean anything which isn’t fastened down or stored correctly.

Afore – Towards the front of the vessel.

Afterbrow – A part of a ship’s hull located aft (or behind) the ship’s prow or stem. The afterbrow is typically a raised part of the ship’s deck, providing extra visibility for the crew when navigating in reverse or manoeuvring in tight spaces.

Ahoy – A cry to draw attention. For example, it can be used to hail a boat or ship “boat ahoy”.

A-hull – Lashing the helm to the leeward side to ride out bad weather without the sails set.

Amidships – The verticle centre of the deck of a vessel between the fore and aft.

Aka – A structural section of a vessel that joins the hulls of a multihulled vessel together.

Alee – On the leeward side of a ship.

All hands – The entire personnel onboard a ship. Often commonly used colloquially as “all hands on deck”.

AIS – Automatic Identification System.

Astern – Towards the rear of the vessel.

Astarboard – Towards the starboard side of the vessel.

ARPA – Automatic Radar Plotting Aid.

Athwartships – At a right angle to the aft and fore line of the vessel.

Azimuth circle – an instrument used to take the bearings of celestial objects.

Azimuth compass – An instrument for determining the sun’s position concerning the magnetic north for directional purposes.

Nautical Terms B

Back – When the wind starts to shift in an anti-clockwise direction.

Back a sail – Sheeting the sail to the windward direction, so the wind fills the sail on the leeward side.

Backstay – The stay supports the aft from the mast, preventing its forward movement.

Back wash – Water forced astern by the action of the propeller.

Baggywrinkle – A soft covering for standing rigging which reduces sail chaffing.

Bailer – any device or container used to remove water that has entered the vessel.

Balance rudder – Usually a set of three or four rudders which operate simultaneously to manoeuvre a sternwheel steamboat.

Ballasts – Heavy material, often iron or lead weights, fixed in a low-access area to stabilise the vessel.

Ballast tank – A compartment filled or partially filled with water to help control the vessel’s buoyancy and is often found on submarines.

Bar – A mass of sand or earth raised higher than the general levels of the seabed by the motion of water. They are often found at the mount of rivers or harbours and can make navigation challenging.

Barber hauler – A technique of temporary rigging a sailboat lazy sheet to allow a boat to sail closer to the wind.

Beam – The widest point of the deck on a vessel.

Bear away – To steer the vessel away from the wind.

Beat – To take a zig-zag approach to the wind or close-hauling with alternative tacks.

Bearing – The horizontal direction of a line of sight between two objects on the earth’s surface.

Becalmed – When a sailing vessel cannot move due to the lack of wind and is drifting with a current that cannot be managed.

Belay – To fasten the rope around the cleat using a figure of eight knot.

Bend – To secure a sail to the spar before raising it or connecting two ropes using a knot.

Berth – A sleeping quatres on a boat or a location in a port or harbour used for mooring vessels whilst not at sea.

Bight – A loop in a rope or line without access to the ends.

Bilge – The compartment at the bottom of the hull where water collects and must be pumped out of the vessel.

Bird farm – A US Navy slang term for an aircraft carrier.

Block – The pulley fixed inside a plastic or wooden casing with a rope running around a sheave and changing to a pulling direction.

Bonnet – An additional strip of canvas laced to the foot of a sail to increase its area in light winds.

Boom – A floating barrier to control navigation into and out of rivers or harbours, but is also known as the spar attached to the foot of a fore and aft sail.

Boot-top – The area on a ship’s hull along the waterline and is usually painted a contrasting colour. This can help measure the weight of a boat, as we discovered in how large ships float.

Broach – When a sailing or power vessel loses directional control when travelling with a following sea. The ship turns sideways to the wind and waves and may capsize or pitchpole in more severe cases. Advice on dealing with heavy weather includes various strategies for avoiding this happening.

Broad reach – The point of sailing the vessel between a run and the beam reach with the wind blowing over the quarter.

Bulkhead – An upright wall within the hull of a ship, particularly a watertight, load-bearing wall.

Nautical Terms C

Cable length – A measure of length or distance equivalent to 1⁄10 nautical mile (608 feet; 185 metres) in the United Kingdom and 100 fathoms (600 feet; 183 metres) in the United States; other countries use different equivalents.

Center-line – The centre of a vessel along the aft to fore line.

Center-board – A wooden board or metal plate which can be pivoted through a fore-and-aft slot along the centre line in the hull of a sailing vessel. It functions as a retractable keel to help the boat resist leeway by moving its centre of lateral resistance.

Chaffing – Wear on a line or sail caused by constant rubbing against another surface.

Claw ring – The fitting slipping over the boom like a claw. It attaches to the main sheet after you finish reefing the sail.

Chartplotter – An electronic instrument that places a ship’s position from a GPS receiver onto a digital nautical chart displayed on a monitor.

Cleat – A stationary device used to secure a rope aboard a vessel.

Close-hauled – The skill of sailing close to the wind, also known as beating.

Clew – One of the lower corners of a square sail, alternatively on a triangular sail, the corner at the end of the boom.

Clipper – A sailing vessel mainly used for speed.

Close reach – The point where you’re sailing between the beam reach and the close-hauled or when the wind blows toward the forward of the beam.

Course – The direction in which you steer the vessel and the journey it intends to make.

Convoy – A group of ships travelling together for mutual support and protection.

Counter – The part of the stern above the waterline that extends beyond the rudder stock concluding in a small transom. An extended counter increases the waterline length when the boat is heeled, so increasing hull speed.

Cringle – A loop of rope, often at the corner of the sail, for fixing the sail to the spar. These are usually reinforced with a metal eye.

The Start of Your Nautical Journey

Although most of this terminology may not be helpful, understanding it can be essential for communicating with other vessels out at sea and is an excellent place to start before venturing into the waters. It can make emergency rescues more efficient and give you the skills to know more about your vessel and those you may encounter on your journeys.

Continue reading our glossary of nautical terms in, A Complete Glossary of Common Nautical Terminology D-L.

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