sailboat terms

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A to Z of Nautical Terms: A Complete Glossary of Boat Terminology

Are you a new boat owner? Whether you bought a jet ski or a 40-foot cabin cruiser, you’re going to need to understand the lingo while you’re out on the water. Here’s a glossary of basic nautical terms to have you sounding like a sailor.

Toward the stern of the vessel.

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

Around or near the stern of the vessel.

At a right-angle to the boat’s center-line.

Lashing the helm to the leeward side to ride out bad weather without the sails set.

The center of the deck of the vessel between the fore-and-aft.

Automatic Identification System.

Apparent Wind

The speed and direction of the wind combined with the boat’s movement and the true wind speed and direction.

To look behind the boat while driving in reverse.

Automatic Radar Plotting Aid.

Athwartships

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

The act of measuring the angular distance on the horizon circle in a clockwise method, typically between a heavenly body and an observer.

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.

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

Baggywrinkle

The teased-out plaited rope wound around the stays or shrouds preventing chaffing.

Iron or lead weights are fixed in a low-access area of the vessel or on the keel to stabilize the boat.

A flexible and lightweight strip feeds into the sail leech’s batten pocket, supporting the roach.

Ballast Keel

A ballast bolted to the keel, increasing the vessel’s stability to prevent capsizing.

The widest point of the vessel or a traverse member supporting the deck. On the beam, objects are at a right-angle to the center-line.

Taking the action of steering the vessel away from the wind.

To tag a zig-zagging approach into the wind or close-hauling with alternate tacks.

The object’s direction from the observer measured in magnetic or true degrees.

To fasten the rope around the cleat using a figure-8 knot.

Securing the sail to the spar before hoisting it or connecting two ropes using a knot.

A sleeping quarters on a boat or a slip occupied by a vessel in a marina or harbor.

The loop or bend in a knot.

The round, lower part of the hull where the water collects.

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

Boot-Topping

The narrow-colored stripe is painted between the topside enamel and bottom paint.

The heeling action of the boat when it slews to the broadside while running downwind. Abroach usually occurs in heavy seas.

Broad Reach

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

The partitioning wall in the vessel athwartship.

A measurement of distance equal to 0.1-sea mile, 185-meters, or 200-yards.

Center-Line

The center of the vessel along the aft-to-fore line.

Center-Board

A board lowers through a slot on the keel for reducing leeway.

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

Chart Datum

The reference level on the charts below which the low tide level. The sounding features below the chart datum. The datum level varies depending on country and area.

The metal, wooden, or plastic fitting used to secure ropes.

Close-Hauled

The skill of sailing close to the wind, also known as beating.

The lower, aft corner of the sail where the leech and foot meet.

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.

The direction that you steer the vessel in degrees. Mariners can use true or magnetic readings or use a compass to plot the course.

Close-Winded

The act of sailing a boat close to the wind.

The rope loop at either end of the line reef points or an eye in a sail.

The difference between the direction indicated by the magnetic meridian and the compass needle, caused by carrying metal objects aboard the vessel.

Sailing with the wind blowing to the aft, in line with the center-line of the vessel.

Displacement

The displacement hull design displaces boat weight in the water and is only supported by its buoyancy.

The weight of the water displaced by the vessel is equal to the vessel’s weight.

The rope used to pull down the spar or sail.

To float the vessel with the wind or current. Or the distance covered by the boat while drifting in the current, measured in time.

The distance between the lowest point on the keel and the center-line of the vessel measured as a vertical distance.

The sea anchor thrown over the stern of a life raft or boat or to reduce drift.

Digital Selective Calling (a function on Marine radios ).

A retractable keel drawn into the vessel’s hull.

Emergency Position Indication Radio Beacon.

Estimated Position.

Estimated Time of Departure.

Estimated Time of Arrival.

The fitting adjusting the feeding line allows you to change the direction of the lead line.

The raised border on cabin tables, chart tables, preventing objects from falling off the surface.

Measurement of water depth and rope lengths.

• 1 Fathom = 6-feet = 1.83-meters.

The vessel positioning plotted by two or more positioning lines.

The vertical distance between the top of the deck and the waterline.

The closest stay running between the masthead and stemhead, hankering the mainsail.

A large-size headsail is available in various sizes, overlapping the mainsail before hoisting in fresh to light winds on all sailing points.

Two concentric rings pivot at right-angles to keep objects horizontal despite the swaying motion of the boat.

Global Navigation Satellite System.

Global Maritime Distress and Safety System.

To change tack by turning the boat into the eye of the wind.

Booming out the headsail in a windward position using the whisker pole to hold it on the opposite side of the mainsail.

The fitting anchoring the mast to the boom, allowing free movement in all directions.

This metal rail surrounds the boat’s edges, allowing easy gripping to prevent falling overboard.

Turning the stern through the wind to change from one tack to another.

The spinnaker guy controls the steadying rope for the spar through the aft-fore position of the spinnaker pole. The foreguy keeps the spinnaker pole in the forward position.

Global Positioning System.

The rope hoisting the lower sails.

Highest Astronomical Tide.

The fitting for attaching the sail’s luff to a stay.

The deck opening provides the crew with access to the berth or cabin interior.

The streamlined surround of a forestay featuring the groove allows for the sliding attachment of the luff sides of the headsail.

Head-to-Wind

When the bow of the vessel points into the direction of the wind.

The forward motion of the vessel through the water.

The toilet.

The action of backing the jib and lashing the tiller to the leeward side in rough weather conditions. The heave-to encourages the vessel to reduce headway and lie quietly.

When the vessel exaggeratedly leans to one side.

International Maritime Organization.

International Regulations for Preventing Collisions at Sea.

International Telecommunication Union

The lines on weather maps joining places with equal atmospheric pressure.

The temporary device for replacing damaged or lost gear.

The line running from aft-to-fore on both sides of the vessel. The jackstays allow for the clipping attachment of safety harnesses to prevent being lost at sea when falling overboard.

A secondary, smaller, lightweight anchor.

A dual-masted sailboat featuring a mizzen mast that’s slightly smaller than its mainmast, with a stepped forward position of the rudder post/stock.

The center-line of the vessel features the attachment of the ballast keel, allowing for the lowering of the center-board.

Kicking Strap

The line for pulling down the boom or keeping it in the horizontal position when on a run or reach.

A short length of line attached to an important object that you don’t want to lose, such as the jet ski key. The lanyard can connect to your wrist or lifejacket.

The aft edge of the triangular sail. Both side-edges of a square sail.

Lowest Astronomical Tide.

The shore on which the wind is blowing.

The natural tendency of vessels to bear away from the direction of the wind.

Moving in a direction away from the wind. The direction in which the wind is blowing.

The vessel’s leaning to one side due to improper distribution of weight in the boat’s hull.

The leading edge of the sail. Luffing up is turning the head of the boat into the wind.

The sideways motion off course resulting from the wind blowing on one side of the hull and sails.

The instrument for measuring the distance and speed of a boat traveling through the water. It is also the act of recording the details of a voyage in a logbook.

Marinized engine

A car engine or motorbike motor adapted for use in watercraft.

Maritime and Coastguard Agency.

The keel socket locating the base of the mast.

Measured Mile

The distance marked on charts measures one nautical mile between islands at sea or onshore ranges.

The short after-mast on the yawl or ketch.

This imaginary longitudinal line circling the earth, passing through both poles, cutting at right-angles through the equator.

Mean Low Water Neaps.

Mean High Water Neaps.

Mean High Water Springs.

Mean Low Water Springs.

Maritime Mobile Service Identity.

The rope used for pulling out the sail’s foot.

Overall Length (LOA)

The extreme length of the vessel. The measurement from the aftmost point of the stern to the foremost points of the bow. This measurement excludes the self-steering gear, bowsprit, etc.

An emergency call requesting immediate assistance.

The bowline on a tender or dinghy for towing or making fast.

To gradually let out the rope.

The left-hand side of the vessel when looking forward.

Point of Sailing

The angles of the wind allowing for the sailing of the boat. Or the boat’s course relative to its direction and the direction of the wind.

Your vessel is on its port track when the wind is striking the boat’s port side first, and the mainsail is out to the starboard side.

Line of Position/Position Line

The line on charts shows the bearing of the vessel and the position where the boat mist lie. Or two positional lines providing a location fix.

The steel guard rail fitted to the bow to provide additional safety for the crew when working around the boat’s edge.

The steel guard rail fitted around the stern of the boat to prevent the crew from falling overboard.

The section of the vessel midway between the beam and the stern.

The difference in water levels between the high and low tides is the range of tides. Or the distance at which you can see the light.

The act of reducing the sail surface area through folding or rolling additional materials onto the forestay or boom.

Reefing Pennant

The sturdy line allowing you to pull down the leech cringle or luff to the boom while reefing.

When sailing with the wind blowing onto the beam, with all sailing points between close-hauled and running.

Riding Sail

The small sail you hoist to maintain the steerage way during stormy weather.

The imaginary line cuts through all meridians at the same angle. Or the course of the vessel moving in a fixed direction.

Rigging Screw

The deck fitting allowing for tensioning of the standing rigging.

The act of sailing with the wind to the aft of the vessel and with the sails eased into the wide-out, full position.

The curve in a leech sail extending beyond the direct line formed from clew to head.

Running Rigging

All moving lines like halyards and sheets used for trimming and setting sails.

Search and Rescue.

A vessel with two or more masts and the mainmast featured in the aftermost position.

Search and Rescue Transponder.

The toe-rail holes allowing water to drain off the deck.

The room in which the vessel can maneuver clear of submerged dangers.

The shut-off valve for the underwater outlet or inlet passing through the vessel’s hull.

This is French for “radio silence.” You’ll use it when reporting a distress call or incident at sea.

The act of hoisting a sail. Or how the sails fit or the direction of a tidal stream or current.

A procedure word for identifying safety calls.

A steel link featuring a removable bolt crossing the open end. The shackle comes in various designs, from “S” to “U” shapes and more.

The cables or ropes typically fund in pairs, leading from the mast to the chainplates at the deck level. These shrouds prevent the mast from falling to the side, and it’s part of your standing rigging.

The rope attaching to the boom to the sail’s clew allows for the trimming and control over the sail.

Skin Fitting

A through-hull fitting featuring a hole in its skin allows for air and water passing. The seacock is the accessory used for sealing the cavity when not in use.

A boat with a single-masted design for one headsail and one mainsail.

The general term for any metal or wooden pole on board a boat. The pole gives shape to the sails.

Safety of Life at Sea.

Speed Over the Ground

A lightweight, large balloon-shaped sail for running or reacting.

The horizontal struts attach to the mast and extend to the shrouds to assist with supporting the mast.

The act of joining wires or ropes using a weaving process interlacing the fibers in the cable or rope.

The sail will stall if the airflow over the sail surface breaks up, causing the vessel to lose its momentum.

Standing Part

The part of the line you don’t use when making a knot. Or the part of a rope you use to tie around the knot.

The metal post bolted to the deck in an upright position to support the guard railing.

Standing Rigging

The stays and shrouds provide permanent support to the mast.

Starboard Tack

The vessel is on the starboard tack when the boom is out to post, and the wind strikes the boat’s starboard side.

The right-hand side of the vessel when looking forward.

The rope or wire supports the mast in the fore-and-aft direction. It is a part of the standing rigging for your boat.

The sternward movement of the vessel towards the backward direction.

Steerage Way

The vessel has steerage when it reaches sufficient speed, allowing for steering or answering the helm.

The loop of rope or wire attaches the spar to the block to make a sling.

The railing around the vessel’s stern prevents the crew from falling overboard. Modern yachts do not have the elegant wooden railing of older models. Instead, they feature tubular steel or aluminum railings, called Pushpits.

Telegraph Buoy

The buoy marks the position of a submerged cable.

To pull on the end of the rope or cable, wound around a winch.

The compass mounted over the captain’s berth, allowing for the easy reference to what’s going on in the vessel’s helm.

The metal fitting forming eyes at the end of cables, wires, or ropes.

A description for any small boat, usually inflatable models. These boats will take supplies and people between a larger vessel and the shore.

Thermal Wind

The wind occurring from the difference in the heating of the sea and the land by the sun. The sun heats the land faster than the sea, resulting in the onshore wind from the sea replacing the air rising over the land, causing the “sea breeze” phenomenon.

Thumb Cleat

A small cleat featuring a single horn.

The wooden pegs featuring vertical pairs in the gunwale for constraining the oars for rowing.

Topping Lift

The rope linking the mast to the boom end. It supports the boom, allowing for its lowering and raising.

The progress on the vessel’s journey over the ocean. The trajectory line of the boat.

The sides of the hull between the waterline and the deck.

The netting stretching across the hulls of a catamaran.

A watch period or watch duty at the helm of the vessel.

Traverse beams forming part of the stern and fixed to the sternpost of a wooden ship.

Tricolor Lamp

A lamp displaying red in proper port sectors, green in the starboard sectors, and white astern. Some authorities permit the tri-color light on smaller boats instead of conventional stern and bow lights.

Turk’s Head

A decorative knot featuring variable numbers of interwoven strands that form a closed loop.

The direction and velocity of wind measured by stationary observers. Apparent wind is wind experienced by moving objects.

Sturdy steel fittings used for attaching standing rigging to the spar or mast.

The low, forward corner of the sail. Or the action of turning the boat through the wind to get it to blow on the other side of the sails.

Sailing close-hauled to work windward on an alternate course. The wind is on one side then the other.

The low strip of steel, wood, or strapping running along the edge of the deck. You’ll use it in combination with the hand railing to hold your feet to the deck to prevent falling overboard.

The rise and fall of the ocean are caused by the moon’s gravitational effect on the earth and the ocean.

The line moving from the mast had to the spar or the boom used in raising it.

To adjust the sail angle using sheets to achieve optimal efficiency from the sail. Or it describes the action of adjusting the load, influencing the fore-and-aft angle at which it floats.

The course of the boat making good on its travel plan. A fitting of on the boom or mast to the slide on the sail fit. The fitting along which the traveler runs for altering the sheet tension.

The speed and direction of the wind when anchored, stationary on the water, or land.

Turn Buckle

The apparatus used for tightening the standing rigging on the vessel.

A line used in raising something like a spinnaker pole vertically.

The vessel is underway when it releases it fastening to shore when it is not aground or at anchor.

See kicking strap.

The wind will veer when shifting in a clockwise direction. Veering can also mean paying out anchor rope or cable in a controlled manner.

Velocity Made Good

Very High Frequency

The disturbed water left behind (astern) the boat as it moves forward in the water, usually caused by a motor.

Weather Helm

The tendency of the vessel to turn into the wind.

The distance between the radio waves.

Weather Side

The side of the vessel to which the wind is blowing.

World Geodetic Survey of 1984 (most common chart datum).

A mechanical device featuring a cable or line attached to a motor. The winch pulls the boat aboard the trailer and helps with the vessel’s launch from the trailer. The winch also gives more pulling power to withdrawing nets or other apparatus from the water.

Whisker Pole

A lightweight pole used for holding the clew out of the headsail when on a run.

The winch features a vertical handle and a horizontal shaft used in hauling up the anchor chain.

The parts of the vessel that increase the drag on the boat. Examples would be the spars, rigging, etc.

The direction from which the wind blows toward the wind (the opposite way to leeward).

Cross Track Error. The perpendicular distance between two waypoints off track.

A dual-masted vessel with its mizzen stepped aft of its rudder post/stock.

John is an experienced journalist and veteran boater. He heads up the content team at BoatingBeast and aims to share his many years experience of the marine world with our readers.

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