Glossary

A heavy hook- or plow-shaped device, connected to the boat by a rope or chain rode, which is cast to the seabed to immobilize the vessel (anchoring).

The act of dropping anchor to secure a vessel or object to the seabed or riverbed.

It is the wind created by the boat’s movement and speed. This wind has the characteristic of always coming from the direction the boat is moving, affecting the true wind direction. If a motorboat moves forward at 20 knots, it will have wind of the same strength coming in over the bow, regardless of the direction it is heading.

In very general terms, it is the force exerted by the weight of the atmosphere on the Earth’s surface. Since air has mass, gravity pulls it towards the Earth, generating constant pressure on everything at the surface. Atmospheric pressure varies according to altitude and temperature. A higher temperature makes the air less dense and, as such, results in lower atmospheric pressure. (see cold front and warm front)

A high-strength steel cable that connects the top of the mast to the stern of a vessel, preventing longitudinal movement of the mast toward the bow and counteracting the force created by the forestay or genoa. The backstay can also be adjusted for better sail performance.

Maximum width of a vessel.

Part of the hull located between the bow and the stern, referring to the center of the vessel.

Intentional movement of the helm that turns the bow away from the wind direction.

Sailing towards the wind. Because sailing directly into the wind is not possible for sailboats, this point of sail involves sailing at close angles (30 to 45º) relative to the wind direction. In other words, to reach a point that is upwind, a sailboat will have to zigzag to that point. There are two types of beating: Close-hauled (the angle of attack closest to the true wind direction) and Close reach (a less sharp angle of attack relative to the true wind).

Canvas or other material cover that provides shade from the sun for a boat’s passengers.

Horizontal spar fixed to the mast used to secure the foot of the mainsail. The boom helps maintain the ideal shape at the base of the sail.

Mechanical part or rope system that controls the boom’s angle. It allows you to trim the mainsail by opening or closing the leech and, on larger sailboats, to hold the boom in a horizontal position when the sails are lowered.

The front part of a vessel, characterised by its pointed shape. The shape of the bow determines a vessel’s performance and behaviour.

Area of the hull or topsides of a vessel located between the bow and the beam.

Space below deck that allows you to stay inside the boat.

Space below deck that allows you to stay inside the boat.

A quick-opening metal piece that allows for the temporary fastening of a line to a specific point.

A maritime buoyage system used in navigation to indicate the location of the deepest and safest waters in relation to a specific submerged hazard. They are called cardinal marks because the safe direction to pass is relative to the cardinal points (North, South, East, and West).

A hydrodynamic surface similar to a keel, but generally lighter and sometimes movable or retractable. Its primary function is to prevent the boat’s leeway (displacement to the side opposite the wind) and improve directional stability, being very common in smaller vessels.

A metal or rigid plastic fitting, attached to the boat’s deck or to the dock, shaped like an anvil. It is used to secure mooring lines safely.

A device that prevents a line from running freely in the opposite direction when under load.

Coastal navigation carried out between seaports, generally along the same coastline. It differs from ocean-going (or long-haul) navigation in that it stays closer to shore, often using visual references on land—such as lighthouses, headlands, and geographical features—to help with orientation and course setting.

A specific area of a boat intended for the crew to gather. Located at the stern, its bathtub-shaped structure set into the hull allows easy access to the cabin. The cockpit is where all the essential elements for navigation are concentrated.

This occurs when a mass of cold, dense air advances, displacing a mass of warm air. Because it is denser and heavier, the cold air pushes the warm air upwards abruptly, causing strong and rapid instability. It creates clouds with significant vertical development (Cumulonimbus), associated with short, intense rainfall, thunderstorms, wind gusts, and a sharp drop in temperature.

A long pole with a hook at the end, very useful for assisting with docking manoeuvres, to pull or push the boat against the quay, or to retrieve lines and objects that have fallen into the water.

A system that lets you fine-tune the mainsail by tensioning the luff without touching the halyard (avoiding the time-consuming process of heading the boat into the wind). This adjustment delivers better performance depending on wind strength.

Natural movement of water in a given direction and with a given intensity. The current is directly associated with the tides and knowledge of it is essential for safe and comfortable navigation.

The surface of the hull where people spend time and handle the boat’s equipment.

Instrument used to measure the depth of the water where a vessel is navigating.

The action of bringing a boat close to a pontoon or quay, in order to tie and secure the vessel, for passenger boarding or disembarking or loading or unloading of goods.

It is the distance from the waterline to the deepest point of the keel. The draft determines the minimum depth required to navigate over the seabed.

A dangerous situation in which the anchor cannot bite into the seabed (or breaks free) and the boat, even though anchored, is dragged by the force of the wind or the current.

A subtle change in a vessel’s course caused by the movement of the current. A strong current can cause a boat to drift from its destination without having changed its heading, which will require constant corrections to the pre-established course.

It is the opposite of trimming in. The act of easing the sheet, reducing its tension and allowing the sail’s angle relative to the wind to open up.

An onboard emergency radio beacon that, when activated (automatically or manually), transmits an SOS signal with its location to the coast guard. This life-saving equipment is responsible for saving countless lives in the event of a shipwreck.

Inflatable high-density rubber pads that protect a vessel from contact with other boats or the mooring dock.

Lower edge of a sail, horizontal and parallel to the deck (staysail) or to the boom (mainsail). At the ends of the foot are located the tack and the clew.

A high-strength steel cable that connects the top of the mast to the bow of a vessel, preventing the mast from moving longitudinally towards the stern. It is also the cable along which the forestay sail (or genoa) runs when it is hoisted or lowered, and where the luff rests.

A meteorological front is the transition zone or boundary where two air masses with different temperatures, humidity levels, and densities meet.

A triangular sail located at the bow of the boat, with a foot length that extends past the mast. If it does not extend past the mast, it is referred to as a staysail. The genoa consists of three sides: the luff, the leech, and the foot. It is a sail used when sailing upwind. Due to its larger sail area, it is more effective in light winds.

A line used on a boat to hoist or lower sails. Halyards are lines that allow sails to be worked vertically, making them easy to identify as they run from the top of the mast to a fixed point on the deck.

The upper part of the sail, corresponding to the top, where the halyard is attached.

The determined direction of a vessel relative to geographic north. It can be determined by a compass or by a reference point.

Positioning the bow in the true direction of the wind, eliminating all pressure on the sails.

Intentional helm movement that brings the bow closer to the wind direction.

Manoeuvre to suspend the intentional forward motion of a boat, without it moving forward or backward.

Sideways tilt of the vessel, usually caused by the wind’s force on the sails or by uneven weight distribution on board. The keel, the hull’s weight, and sail trim help counteract heeling.

Crew member responsible for steering the vessel, handling the helm (via the tiller or steering wheel) and maintaining the desired course.

The act of raising the sails by handling a halyard.

The main structure of a boat that, in contact with water, allows it to float. The hull can be divided into three formats: monohull (one hull), catamaran (two symmetrical hulls side by side), and trimaran (two symmetrical hulls at the extremities and one asymmetrical hull in the middle).

A medical condition defined by the drop of the average core temperature of the human body below 35°C. A body enters hypothermia when it dissipates more heat than it can produce, occurring due to prolonged exposure to cold. Hypothermia is a serious occurrence that can lead to death, and the affected body must be warmed urgently and gradually, with the most practical and recommended technique being direct contact with another human body.

A triangular sail located at the bow of the boat, whose length does not exceed the distance from the bow to the mast. If it does, it is called a Genoa. The jib is composed of three sides: luff, leech and foot. It is a sail used when sailing close-hauled and, when properly trimmed, allows a tighter angle to the wind (close-hauled) and immediate power.

A maneuver used when sailing downwind to change tack, meaning to steer the boat in a direction where the wind causes the sails to shift from one side to the other.

A longitudinal structural member that runs along the bottom of the hull, acting as the boat’s “backbone”. On sailboats, the keel is usually deep and heavy to lower the vessel’s centre of gravity and prevent it from capsizing. It counteracts the force exerted by the wind on the sails.

In addition to being a unit of speed, the term “knot” also refers to the various types of loops, joins and turns made in ropes, which are fundamental for safety and manoeuvring on board. There are many types of knots (e.g. bowline, figure-eight knot, reef knot), and each has its specific function. Their main characteristic is that they are easy to undo or adjust, during or after heavy loading.

A unit of speed used in the nautical environment, equivalent to 1.85 km/h. One knot is equal to one nautical mile per hour, and this conversion is the appropriate way to estimate the duration of a passage based on a boat’s average speed. For example, if a sailor wishes to travel a distance of 20 miles at a cruising speed of 10 knots (or 10 miles per hour), they will know that it will take 2 hours to reach their destination.

The vertical aft edge of the sail, opposite the luff.

A term used to indicate or refer to the direction of the wind in relation to a vessel or buoy. It refers to the direction the wind is blowing towards.

A race measurement corresponding to the course between two buoys that make up the course. A one-lap technical race has two legs: the windward leg (the course between the starting line and the windward mark) and the leeward leg (the course between the windward mark and the finish).

Inflatable raft, appropriate for the size and maximum capacity of passengers, to be used in case of shipwreck or fire. It is an essential lifesaving resource for any vessel.

A tall, high-powered structure that emits unique light signals, alerting mariners to the presence of land. Lighthouses are vital for orientation and safety during night navigation.

The act of lowering or dropping the sails.

The vertical edge of a sail attached to the boat by a fixed element (mast or forestay). In some cases, on smaller sails, it is the line connecting the head to the tack.

A triangular (or similar) sail attached to the mast and boom. It is the main sail of a vessel and determines the boat’s heeling angle (lateral tilt) and its constant speed. It consists of three sides: luff, leech, and foot.

Vertical structure fixed to the hull of sailboats, supported by the shrouds, forestay and backstay, which supports the sails and other equipment related to sailing.

A distress call transmitted via radio or satellite, indicating an emergency involving danger to people or vessels. Upon receiving the signal via radio (channel 16), all vessels in the vicinity are required to respond to the request for assistance.

A set of ropes or lines used to secure a vessel to the dock.

A map used by sailors to navigate in coastal or oceanic waters. These charts include all the information necessary for safe navigation (depth, seabed composition, hazards, lighthouses, prevailing currents, and harbors of refuge).

A unit used to measure nautical distance. One nautical mile equals 1,852 metres, and one nautical mile per hour equals one knot of speed.

A station on a vessel that controls the handling of most lines used in sailing, through clutches resembling piano keys. The complexity of each station depends on the individual boat.

The longitudinal oscillating movement of a boat caused by waves, in which the bow and the stern alternately rise and fall.

Term that defines the boat’s position or angle in relation to the wind direction. The main points of sail are: close-hauled (into the wind), beam reach (wind abeam), and running (wind from behind).

Term used to refer to the left side of the vessel, in the stern-to-bow direction. The origin of the word is uncertain, but the most widely accepted theory comes from the English, who used it to refer to the side where land was (Port) when sailing down the Atlantic Ocean towards the south. In Portugal, it was adapted as Bom Bordo, because it was the side of the boat facing land and the safe, charted ports when navigating along the African coast. The opposite of port is starboard.

Area of the hull or side of a vessel located between the stern and the beam.

Sailing with the wind coming in from the beam. Sailing on a reach is sailing at a midpoint between close-hauled and running. It is a point of sail that allows fast and comfortable sailing, though it is potentially dangerous in the presence of breaking waves.

The act of reducing the sail area of a mainsail on a vessel. It is the appropriate procedure to follow when the wind strength exceeds the limit for using the sail at full capacity. By reefing, you can control the amount of pressure hitting the sails, making the vessel more manageable and navigation safer and more efficient.

A sporting competition involving boat races. Regattas can be divided into ocean, coastal, and technical categories. While the course of ocean and coastal regattas is determined by the distance between point A and point B, in technical regattas the circuit is determined by the distance between buoys deployed for that purpose.

A vessel’s steering device, similar to an oversized steering wheel. It is an alternative to the tiller and, as a rule, is used on larger boats.

The act of passing around a buoy in order to change direction to a new predetermined course.

A hydrodynamic or aerodynamic control device used to steer and direct the course of a vessel or aircraft. It consists of a flat or shaped surface (blade), mounted on a vertical hinged axis, which changes the vehicle’s trajectory by redirecting the flow of water or air passing through it.

Lightweight, durable material with a specific geometric shape, hoisted to enable a sailboat to sail. A sail works like an airplane wing, but vertically, creating, as the wind passes, a high-pressure zone on one side and a low-pressure zone on the other, generating lift that, with the help of the keel/centerboard and the rudder, moves the boat forward in the desired direction. There are various types of sails depending on their purpose, position, and wind strength.

If sailing close-hauled means sailing against the wind, sailing downwind means sailing with the wind. This is the point of sail where the wind enters from the stern and is associated with the gybing maneuver and the use of the spinnaker. In this point of sail, one can sail at a tighter angle with the wind entering over the quarter (Broad Reach) or at a wider angle with the wind entering directly over the transom (Dead Run).

The set of sails that make up a vessel.

Rope used on a boat to trim in or ease sails. Sheets are lines that allow sails to be worked horizontally. In the case of the spinnaker, they are called Alantas.

The corner opposite the tack, where the sheet is attached.

A set of steel cables, fixed to port and starboard, that support the mast in a transverse direction.

An opening in the deck, usually protected by a glazed surface. Its purpose is to allow light and/or ventilation into the cabin interior.

SOG tells us the actual speed at which a vessel moves over the seabed. It is speed over the ground, regardless of the water’s speed.

It is the speed at which a vessel moves through the water. This speed is commonly affected by the strength of the current. If a boat is travelling at 5 knots and the current is against it at 2 knots, the speed through the water is 5 knots, but the SOG is only 3 knots.

A balloon-shaped sail made of ultra-lightweight material, used for better performance when sailing downwind. The spinnaker, or ‘spi’, has the unique characteristic of extending almost entirely outside the boat, connected by a halyard at the top of the mast and by the sheets.

A horizontal spar extending from the mast toward the sides of the vessel. Each mast has several, from the base to the top, and their primary function is to strengthen and stabilize the mast, serving as the support point for the shrouds.

A mooring line used to secure a vessel, preventing it from moving forward or backward at the dock.

Term used to refer to the right-hand side of the vessel when facing forward. The origin of the word is divided, with the most widely used theories coming from medieval Nordic boats that used a long oar serving as a rudder (styriboard = rudder side) or from the English, when referring to the side where the unknown sea and the stars lay (Starboard), as their caravels sailed down the Atlantic Ocean heading south. The opposite of starboard is port.

The rear part of a vessel, located between the mast and the transom. It is the area opposite the bow.

The end of one side of a sail’s foot, which is secured to the hull or another fixed point on a boat.

Relative position to another vessel of the same type and with the same means of propulsion that gives us right of way.

A manoeuvre used when sailing close-hauled and you want to change tack. Although tacking means sailing in almost opposite directions, since each tack can involve a course change of around 90°, the direction of travel remains the same.

The act of sailing close-hauled in a zigzag, making successive tacks (turns) to reach a destination that lies directly upwind.

The cyclical movement of ocean and sea waters, resulting primarily from the gravitational influence of the Moon. This rising and falling movement of the sea level occurs approximately every twelve hours, and its intensity depends directly on the phase of the moon. This rise or fall causes the movement of the current.

Part of the rudder that allows the helmsman to handle the boat. An extension can be added to the tiller for more comfortable and suitable use by the helmsman.

Lines used to control the spinnaker’s position relative to the wind.

A line that supports the boom horizontally when the mainsail is lowered. On smaller boats, it is common to use the mainsail halyard for this purpose.

The part of a vessel’s hull that is above the waterline. It is the visible portion of a boat when it is afloat.

The rear part of a hull that marks its end. Many boats use this panel to display their name and port of registry. It is the opposite of the bow.

The act of adjusting the sails relative to the wind, i.e., tightening or easing the sails. The closer to the wind you sail, the tighter the sails will be; the more downwind, the looser they will be.

The act of pulling the sheet to close the angle of the sail in relation to the wind. The closer to the wind you sail, the more the sails need to be trimmed, that is, the closer to the center of the boat they need to be.

Natural wind coming from a specific direction.

The part of a boat’s hull that is below the waterline when it is afloat; in other words, the submerged part of the hull that is exposed to the living organisms in the sea.

This occurs when a mass of warm, less dense air advances, overriding a retreating mass of cold air. Because warm air is lighter, it rises smoothly and gradually over the slope of cold air, causing a slower and more continuous weather transition. It begins with high clouds (Cirrus) and evolves into low, dense clouds (Nimbostratus), resulting in moderate, continuous, and prolonged rainfall (reduced visibility or fog), followed by a rise in temperature.

The line where the hull meets the water when the vessel is loaded with its normal cargo and balanced. Below the waterline we have the underwater body, and above the waterline we have the topsides.

A cylindrical device designed to assist in handling lines that are under tension. Typically used to trim and ease sheets or halyards, and can operate manually via a handle or by electric power.

Natural horizontal movement of air in the atmosphere, caused by differences in atmospheric pressure and temperature between different regions of the planet.

An instrument installed at the top of the mast that indicates, at all times, the apparent wind direction relative to the boat. It is an essential tool for sailing.

Term used to indicate or refer to the direction of the wind relative to a vessel or buoy. It refers to the direction from which the wind comes.