Reference• 18 min read• By Safety Anchor Alarm Team
Sailing Terms Glossary: 199 Nautical Words Explained
Sailing has its own vocabulary, and most of it is not decoration — each word exists because it removes an ambiguity that could cost you a boat. “Left” depends on which way you are facing; port does not. This is every term you are likely to meet on a charter, in a pilot book or in a forecast, defined in one or two sentences, with a table at the top of the words that sound alike and mean very different things.
If you learn only twelve words before your first sail
- Bow / stern
- front / back
- Port / starboard
- left / right, facing forward
- Windward / leeward
- the side the wind hits / the sheltered side
- Line
- any rope with a job
- Sheet
- the line that trims a sail in and out
- Halyard
- the line that hoists a sail up
- Tack / gybe
- turning the bow / the stern through the wind
- Heel
- the sailboat's lean under wind
- Reef
- reduce sail area when it blows
- Rode
- the chain or rope from anchor to boat
- Scope
- rode length ÷ depth — 5:1 by day, 7:1 overnight
- Under way
- not attached to the bottom or the shore
Those twelve make a skipper's briefing intelligible. The rest of this page is the reference you come back to.
The terms people mix up
Almost every misunderstanding on board comes from one of a dozen near-identical pairs. Learning the distinction is worth more than learning fifty new words, because these are the ones that produce the wrong action rather than a blank look.
| Confused pair | The difference that matters |
|---|---|
| Port / starboard vs windward / leeward | Port and starboard are fixed sides of the boat and never change. Windward and leeward depend on the wind, so they swap sides every time you tack. |
| Knot (speed) vs knot (rope) | A knot is one nautical mile per hour — the 'per hour' is already in the word, so 'knots per hour' is wrong. The rope kind is unrelated. |
| Rope vs line vs rode vs warp | Rope is the raw material. It becomes a line once it has a job on board, a rode when it connects you to the anchor, and a warp when it is used for mooring, kedging or towing. |
| Sheet vs halyard | A sheet pulls a sail in and out. A halyard pulls it up and down. Nothing on a boat is called a rope once it does either job. |
| Bowline vs bow line | A bowline (say 'boh-lin') is the knot that makes a fixed loop. A bow line is the mooring line from the bow to the dock. |
| Draft vs freeboard | Draft is how far the boat goes below the waterline — it decides where you can go. Freeboard is how far the deck sits above it, and decides how much windage you carry at anchor. |
| Anchoring vs mooring vs berthing | Anchoring uses your own ground tackle. Mooring means tying to someone else's permanent buoy and chain. Berthing is going alongside in a marina. |
| Spring tide vs neap tide | Spring tides have the biggest range and fall near full and new moon; neaps have the smallest, at the quarters. Neither is a season. |
| Under way vs making way | Under way means not attached to the bottom or the shore — a drifting boat with the engine off is under way. Making way means actually moving through the water. |
| Heel vs list | Heel is the lean the wind puts on a sailboat, and it comes and goes. A list is a permanent lean from weight or water inside the boat, and it is a problem. |
| Give-way vs stand-on vessel | The give-way vessel changes course or speed, early and obviously. The stand-on vessel holds what it is doing so the other one can predict it — until it is clear nobody is giving way. |
| Gybe vs jibe | The same manoeuvre — turning the stern through the wind. Gybe is the British spelling, jibe the American. |
A–Z glossary of sailing and boating terms
199 terms, defined in plain English. Where a word has a guide of its own on this site, the definition links to it.
- Abeam
- At right angles to the centreline of the boat — something abeam is directly off your side, neither ahead nor astern.
- Aftalso: after
- Towards the back of the boat. The aft cabin is the one nearest the stern.
- Aground
- Stuck on the bottom, with the keel or hull touching the seabed. Running aground on a falling tide is worse than on a rising one, because the water keeps leaving.
- Amidships
- The middle of the boat, either fore-and-aft or side-to-side. A helm held amidships is centred.
- Anchorage
- A place where boats can anchor with reasonable shelter and holding. A good anchorage is defined by the wind it protects you from, not by how pretty it is. Read more →
- Anchor bendalso: fisherman's bend
- The traditional knot for joining a rope rode to an anchor: two round turns through the ring, a half hitch passed under both of them, a second half hitch above, and the tail seized to the standing part. Read more →
- Anchor lightalso: riding light
- An all-round white light shown at the masthead or forestay when anchored at night, so other boats can see you. Required outside designated anchoring areas in most waters. Read more →
- Anchor watch
- Keeping check that the boat is staying where it anchored — traditionally a person on deck, now usually a GPS anchor alarm that wakes you if the boat leaves its circle. Read more →
- Apparent wind
- The wind you actually feel on the moving boat: the true wind combined with the wind created by your own speed. Instruments read apparent wind; sail trim responds to it.
- Astern
- Behind the boat, or moving backwards. Going astern means engaging reverse.
- Athwartships
- Across the boat, from side to side — the opposite axis to fore-and-aft.
- Autopilot
- A device that steers the boat to a set compass heading or wind angle. It holds a course; it does not keep a lookout.
- Backstay
- The wire running from the masthead to the stern that stops the mast falling forward. On many cruising boats it is adjustable to bend the mast and flatten the mainsail.
- Bareboat charter
- Chartering a yacht without a skipper or crew — you sail it yourself. The charter company checks your experience and usually your sailing qualification.
- Batten
- A stiff strip slid into a pocket in the mainsail to hold the curve of its trailing edge. Full-length battens run the whole width of the sail.
- Beam
- The width of the boat at its widest point. Also used for direction: a wave on the beam hits you side-on.
- Beam reach
- Sailing with the wind coming across the beam, at roughly 90° to the boat. Usually the fastest and most comfortable point of sail. Read more →
- Bear awayalso: bear off, fall off
- To steer away from the wind, so the boat turns towards a downwind course. The opposite of luffing up.
- Beating
- Sailing towards a point upwind by tacking repeatedly, since no boat can sail straight into the wind. The zig-zag adds distance — expect to sail 1.4 times the direct distance. Read more →
- Berth
- Two meanings: a bed on board, and a place where the boat is parked in a marina. Also 'give it a wide berth' — pass with room to spare.
- Bilge
- The lowest inside part of the hull, where water collects. A bilge pump empties it; a dry bilge is one of the fastest ways to notice a new leak.
- Bimini
- A folding fabric canopy over the cockpit that gives shade. Distinct from a sprayhood or dodger, which shelters the companionway from spray.
- Bitter end
- The very last of a rope or chain — the end attached to the boat. The reason the phrase matters: your anchor chain's bitter end should be secured, but with something you can cut.
- Block
- A pulley. Ropes run through blocks to change direction or to gain mechanical advantage when several are used together.
- Boom
- The horizontal spar along the bottom of the mainsail. It swings across the cockpit during a tack or gybe, which is why the name is a fair warning.
- Bow
- The front of the boat. The bow roller at its tip is where the anchor lives and where anchor scope is measured from.
- Bowline
- Pronounced 'boh-lin'. The knot that puts a fixed loop in the end of a rope, holds under load and unties afterwards. Not the same thing as a bow line, which is a mooring line from the bow.
- Bridle
- A two-legged rope arrangement that shares a load between two points — used on catamarans to take the anchor snubber to both bows.
- Broach
- An unwanted, sudden slew sideways when running downwind, where the boat rounds up and lies over. Usually the result of too much sail and a following sea.
- Bulkhead
- An internal wall that divides the inside of the boat and stiffens the hull. Structural bulkheads carry rigging loads, so damage to one is never cosmetic.
- Buoy
- A floating mark. Navigation buoys mark channels and dangers; mooring buoys are laid for boats to tie to instead of anchoring.
- Burgee
- A small triangular flag, usually a sailing club's, flown from the masthead. It also makes a useful wind indicator.
- Catamaran
- A twin-hulled boat. Cats sit flat rather than heeling, draw less water, and swing differently at anchor from a monohull because of their wide bows and light displacement.
- Chafe
- Wear caused by a rope rubbing against something. Chafe is the quiet reason mooring and anchor lines fail overnight, so anywhere a line crosses an edge gets protection.
- Chain locker
- The compartment in the bow where anchor chain is stowed. Chain that piles into a cone can jam the windlass on the way out.
- Chain stopper
- A hinged pawl on the foredeck that drops into a link and holds the anchor chain independently of the windlass. It exists so the static load at anchor goes into the boat's structure rather than the windlass gearbox. Read more →
- Chart datum
- The reference water level that charted depths are measured from — usually the lowest tide realistically expected. Real depth is charted depth plus the height of tide.
- Chartplotter
- A fixed navigation display showing your GPS position on an electronic chart. Many include an anchor drag alarm, though it measures from the boat's position, not the anchor's. Read more →
- Cleat
- A fitting with two horns that a rope is made fast to. The cleat hitch — a turn, then figure-eights, then a locking hitch — is the knot for it.
- Clew
- The bottom rear corner of a sail, where the sheet attaches. The other corners are the tack (bottom front) and the head (top).
- Close-hauled
- Sailing as close to the wind as the boat will go with sails trimmed in hard — typically about 40–45° off the true wind. Read more →
- Coachroofalso: cabin top
- The raised roof over the cabin, standing above deck level.
- COLREGs
- The International Regulations for Preventing Collisions at Sea — the rules of the road, covering who gives way, what lights and shapes are shown, and sound signals. Read more →
- Companionway
- The main entrance from the cockpit down into the cabin, usually a set of steps under a sliding hatch.
- Course
- The direction you intend to travel, in degrees. It differs from your heading once tide or leeway pushes the boat sideways.
- Current
- Horizontal movement of water. Tidal current changes with the tide; ocean current does not. Either will move you off course whether or not you notice.
- Davits
- The arms at the stern that hoist and carry the dinghy. Handy at anchor, vulnerable in a following sea.
- Dead reckoning
- Working out your position from a known point using course, speed and time elapsed — navigation without GPS. Still the backup when electronics fail.
- Depth sounderalso: echo sounder
- The instrument that measures water depth under the boat. Know whether yours reads from the waterline, the transducer or the bottom of the keel — the difference is the number that matters when it gets shallow.
- Dinghyalso: tender
- The small boat used to get ashore from an anchored yacht. At night it is towed short or lifted, so it cannot get under the hull or foul the propeller.
- Displacement
- The weight of the boat, equal to the weight of water it displaces. Heavy displacement means more momentum and more load on ground tackle in a blow.
- Dodgeralso: sprayhood
- The fabric shelter over the companionway that keeps spray out of the cockpit.
- Downwind
- In the direction the wind is blowing. Sailing downwind feels calm because the apparent wind drops — which is exactly why it is easy to carry too much sail.
- Draftalso: draught
- How deep the boat sits — from the waterline to the lowest point of the keel. It tells you where you cannot go; freeboard tells you how far the deck is above the water.
- Dragging
- When the anchor stops holding and ploughs along the bottom, letting the boat move downwind. It usually starts slowly and silently, which is why anchor alarms exist. Read more →
- Drogue
- A device streamed astern in heavy weather to slow the boat and keep it stern-to the waves. A sea anchor does the opposite job from the bow.
- Ease
- To let a rope out gradually under control — the opposite of trimming in. 'Ease the mainsheet' means let the boom out a little.
- Ebb
- The falling tide, when water flows away from the coast. Anchoring on an ebb means checking you will still have depth at low water.
- EPIRB
- Emergency Position Indicating Radio Beacon — a device that transmits your identity and position to search and rescue by satellite when activated. A PLB is the personal, smaller version.
- Fairlead
- A fitting that guides a rope in the right direction without chafe, typically where mooring lines leave the deck.
- Fathom
- Six feet, or 1.83 metres — the traditional unit of depth still printed on older charts. Not to be confused with a nautical mile.
- Fender
- An inflatable cushion hung over the side to protect the hull against a dock or another boat. Fenders belong at the height of what you are protecting against, not just over the rail.
- Fetch
- The distance of open water the wind has blown across. Long fetch builds bigger waves, which is why an anchorage that looks sheltered can still be rolly if it opens onto miles of open sea.
- Flake
- To lay a rope or sail down in loose folds so it runs out without tangling. Flaking chain on deck before dropping is how you avoid a jam at the wrong moment.
- Flood
- The rising tide, when water flows towards the coast. The opposite of ebb.
- Following sea
- Waves coming from behind. Comfortable until they start to steer the boat, at which point they invite a broach.
- Foredeck
- The deck area forward of the mast, where anchoring, sail changes and mooring lines are handled.
- Forestay
- The wire from the bow to the masthead that holds the mast up from the front, and which the headsail is set on.
- Freeboard
- The height of the deck above the water. High freeboard keeps you dry but gives the wind more to push on, so the boat sails around its anchor more.
- Furl
- To roll or gather a sail away. Roller furling rolls the headsail around the forestay; reefing is furling only part of it.
- Galley
- The kitchen on board. Gimballed cookers stay level while the boat heels.
- Genoaalso: genny
- A large headsail that overlaps the mast. Bigger than a jib and the workhorse sail on most cruising yachts.
- Gimbal
- A pivoting mount that lets something — a cooker, a compass — stay level as the boat heels.
- Give-way vessel
- Under the COLREGs, the boat required to take early and obvious action to keep clear. The other one is the stand-on vessel, which holds its course and speed. Read more →
- Gooseneck
- The hinged fitting that joins the boom to the mast.
- Ground tackle
- The whole anchoring system taken together: anchor, chain or rope rode, shackles, swivel, snubber and windlass. It is only as strong as its weakest shackle. Read more →
- Gunwale
- Pronounced 'gunnel'. The top edge of the hull where it meets the deck.
- Gybealso: jibe
- Turning the stern through the wind so the boom crosses to the other side. Same manoeuvre, two spellings — gybe in Britain, jibe in America. An uncontrolled one is the most dangerous routine event on a sailboat.
- Gypsyalso: wildcat
- The notched wheel on a windlass whose pockets are machined to take one specific chain size and pitch. It grips by shape rather than friction, which is why a chain of the right diameter but the wrong standard still jumps. Read more →
- Halyard
- The rope that hoists a sail up. A sheet pulls a sail in and out; a halyard pulls it up and down.
- Hank
- A clip that attaches the leading edge of a headsail to the forestay, on boats without roller furling.
- Hatch
- An opening in the deck with a lid, for light, air or access. Closing hatches is a pre-departure item precisely because an open one only matters once. Read more →
- Haul out
- Lifting the boat out of the water, for maintenance, antifouling or winter storage. Read more →
- Head
- The toilet on board — and also the top corner of a sail. Context does the work.
- Heading
- The direction the boat is pointing, in degrees. Not necessarily the direction it is travelling once tide and leeway are added.
- Head-to-wind
- Pointing straight into the wind, with sails flapping. It is where a tack passes through, and where you want the boat to stop when you drop the anchor. Read more →
- Headsail
- Any sail set forward of the mast — jib, genoa or staysail.
- Heave to
- A manoeuvre that parks the boat almost stationary by backing the headsail against a lashed helm. Used to wait out weather, reef, eat, or simply stop and think.
- Heel
- The sideways lean of a sailboat under sail. Normal up to a point; past it the boat slows down and gets harder to steer, which is the signal to reef.
- Helm
- The steering — wheel or tiller — and by extension the person steering.
- Holding ground
- The seabed's ability to hold an anchor. Sand and firm mud hold well, weed and rock badly. Charts abbreviate it: S sand, M mud, R rock, Wd weed. Read more →
- Hull speed
- The theoretical maximum speed of a displacement hull, set by its waterline length. Adding power past it mostly makes a bigger wave, not more speed.
- Inboard
- Inside or towards the centreline of the boat. Also an engine installed inside the hull, as opposed to an outboard hung on the transom.
- In irons
- Stuck head-to-wind with no steerage way, sails flapping — usually the result of a tack that ran out of momentum.
- Jacklinealso: jackstay
- A line or webbing strap run along the deck that a harness tether clips to, so you can move fore and aft while staying attached. The single most useful piece of gear for sailing alone at night. Read more →
- Jib
- A headsail that does not overlap the mast. Smaller than a genoa and the sail of choice as the wind builds.
- Jury rig
- A temporary repair improvised from what is on board. 'Jury' here means makeshift, and has nothing to do with courts.
- Kedge
- A second, smaller anchor — and the act of using one, typically laid out by dinghy to pull the boat off after running aground or to stop it swinging.
- Keel
- The weighted fin under the hull that stops a sailboat sliding sideways and keeps it upright. Its depth is your draft.
- Ketch
- A two-masted rig with the shorter mizzen mast forward of the rudder post. A yawl is similar but has its mizzen further aft.
- Knot
- A speed of one nautical mile per hour — about 1.85 km/h. Because the 'per hour' is already inside the word, 'knots per hour' is wrong. The rope kind is a different word entirely.
- Lazy jacks
- Light lines from the mast to the boom that catch the mainsail as it comes down, instead of letting it fall over the deck.
- Lazy line
- A light pick-up line in a marina berth, handed to you at the quay, leading out to a permanent ground chain on the seabed. It replaces your own anchor when Med mooring — and, like a mooring buoy, it is ground tackle you did not lay and cannot inspect. Read more →
- Lee shore
- A shoreline that the wind is blowing onto. It is the anchoring situation that turns a dragging anchor into a wreck, and the reason shelter is judged against the forecast, not the current breeze.
- Leech
- The trailing edge of a sail. The leading edge is the luff, the bottom is the foot.
- Leeward
- Pronounced 'loo-ard'. The side away from the wind — the sheltered side. Windward is the side the wind hits.
- Leeway
- The sideways slip a boat makes through the water as the wind pushes it. Add it to tidal set and your track over the ground is not your heading.
- Lifeline
- The wire running around the deck at waist height, supported by stanchions, that stops people going over the side.
- Line
- What a rope is called once it is on board doing a job. Sheets, halyards and mooring lines are all lines.
- List
- A persistent lean to one side caused by weight or flooding, not by wind. Heel comes and goes with the wind; a list stays.
- LOA
- Length overall — the boat's total length, which is what marinas charge by. LWL, the waterline length, is what determines hull speed.
- Log
- Two things: the instrument that measures speed and distance through the water, and the written record of a passage. Both answer the same question later — where were we, and when.
- Luff
- The leading edge of a sail; also what a sail does when it flaps because it is not trimmed in enough or the boat is pointing too close to the wind. To 'luff up' is to steer closer to the wind.
- Mainsail
- The sail set behind the mast, on the boom.
- Mainsheet
- The rope controlling how far out the boom, and therefore the mainsail, is let. The primary throttle of a sailboat.
- Make fast
- To secure a line so it will not run — usually to a cleat, bollard or winch.
- Marina
- A harbour with pontoons or berths, shore power and water. The alternative to anchoring, at roughly a hundred times the price.
- Mayday
- The spoken distress call on VHF, used only when there is grave and imminent danger to a person or the boat. Pan-pan is the level below it: urgent, but not life-threatening.
- Med mooring
- Tying stern-to (or bows-to) a quay with the anchor laid out ahead to hold the other end. Standard practice across the Mediterranean and a completely different skill from anchoring free. Read more →
- MOB
- Man overboard. Also the button on a GPS or chartplotter that instantly marks the position, which is the first thing to press and the easiest thing to forget.
- Mooring
- A permanent ground weight, chain and buoy that a boat ties to. Picking up a mooring is not anchoring — you are trusting someone else's tackle, and its service history is rarely posted. Read more →
- Multihull
- A boat with more than one hull — catamaran (two) or trimaran (three).
- Nautical mile
- 1,852 metres, or about 1.15 statute miles — one minute of latitude. It is why the latitude scale at the side of a chart is also its distance scale.
- Neap tide
- The tide with the smallest range, around the first and last quarter of the moon. Spring tides, with the largest range, come near full and new moon — neither has anything to do with the seasons.
- No-go zone
- The arc of roughly 45° either side of the true wind where a sailboat cannot sail. Getting into it accidentally is how you end up in irons.
- Offshore
- Away from the coast, out of sight of land, or an area beyond the reach of quick assistance. Also used of wind blowing from the land out to sea — which makes flat water and hides its own strength.
- Outboard
- An engine mounted on the transom or on the dinghy. Also means towards the outside of the boat, away from the centreline.
- Outhaul
- The control that pulls the clew of the mainsail out along the boom, flattening the bottom of the sail.
- Painter
- The rope permanently attached to the bow of a dinghy for towing and tying up. Its correct length at anchor is 'short enough not to reach the propeller'.
- Pan-pan
- The VHF urgency call — a serious situation that is not yet life-threatening, such as a failed engine in open water. One step below mayday.
- Passage
- A journey from one port or anchorage to another. Passage planning is the process of deciding the route, timings, tides, weather windows and bolt-holes before leaving. Read more →
- Pay out
- To let chain or rope run out deliberately and under control — what you do with the rode as the boat falls back from the anchor. Read more →
- Pilot bookalso: pilot, cruising guide
- A written guide to a coastline: harbours, approaches, anchorages, hazards and local rules. It covers what the chart cannot say in symbols.
- Pitching
- The fore-and-aft see-saw motion as the bow rises and falls in waves. Rolling is the side-to-side version; yawing is the swing from side to side in direction.
- Point of sail
- The boat's angle to the wind — close-hauled, close reach, beam reach, broad reach or run. It determines how the sails are trimmed and how the boat behaves.
- Port
- The left side of the boat when facing forward. It is a fixed side and never changes, unlike leeward and windward, which depend on where the wind is. Its light is red. Read more →
- Preventer
- A line rigged from the boom forward to the deck to stop an accidental gybe when sailing downwind. Cheap, unglamorous, and the reason many heads are still intact.
- Pulpit
- The stainless guardrail at the bow. The one at the stern is the pushpit.
- Quarter
- The part of the boat between the beam and the stern. A wave on the port quarter is coming from behind and to the left.
- Q flag
- The plain yellow flag flown on arrival in a new country before clearing customs and immigration, meaning the boat requests free pratique — permission to land.
- Rafting up
- Tying alongside another boat rather than to the dock. Lines go ashore as well as to the neighbour, and crossing the other boat's foredeck is the etiquette.
- Reach
- Any point of sail between close-hauled and running — close reach, beam reach or broad reach depending on the angle. Read more →
- Reef
- To reduce sail area in stronger wind by partly lowering and securing the mainsail, or rolling away part of the headsail. The old rule holds: the moment you wonder whether to reef is the moment to reef.
- Rode
- Everything between the anchor and the boat — all chain, or rope with a length of chain at the anchor end. Not a word for rope in general: rode is specifically anchoring rope and chain. Read more →
- Rigging
- The wires and ropes that hold the mast up and control the sails. Standing rigging (shrouds, stays) is fixed; running rigging (halyards, sheets) moves.
- Rolling hitch
- A hitch that grips lengthwise along a chain or an already-loaded rope, where a loop knot would simply slide. The knot for rigging a snubber onto chain or taking the strain off a jammed line. Read more →
- Rudder
- The blade under the stern that steers the boat, turned by the wheel or tiller. It only works while water is flowing past it, which is why steering dies as the boat stops.
- Rhumb line
- A course of constant compass bearing — the straight line drawn on a chart between two points.
- Scope
- The ratio of rode paid out to the total depth from the bow roller to the seabed. 5:1 for a lunch stop, 7:1 overnight, more in wind — too little scope is the most common cause of dragging. Read more →
- Sea anchor
- A parachute-like device streamed from the bow in heavy weather to hold the boat head to the waves and slow its drift. A drogue does the opposite, from the stern.
- Seacock
- The valve on a hole through the hull, letting you shut off water to or from a fitting. Knowing where every one of them is, and that they still turn, is basic seaworthiness.
- Set
- Two meanings. To set the anchor is to dig it in by pulling back on it until it holds. Tidal set is the direction the current carries you. Read more →
- Shackle
- A U-shaped metal connector closed by a pin, used to join anchor to chain and chain to rode. Its pin gets moused or wired so it cannot unscrew itself.
- Sheet
- The rope that controls how far a sail is let out — mainsheet, jib sheet. Sheets trim sails in and out; halyards raise them.
- Shroud
- The standing rigging wires running from the masthead or spreaders down to the sides of the boat, holding the mast up sideways.
- Slack water
- The short period around high or low tide when the tidal current has stopped before turning. The easy moment to enter a narrow harbour or a tide-swept anchorage.
- Snubber
- A short length of stretchy rope taking the load off the anchor chain and windlass, absorbing shock loads as the boat surges. It also stops the chain grumbling through the hull all night. Read more →
- Sole
- The floor — of the cabin or the cockpit.
- Spinnaker
- A big, light, balloon-shaped downwind sail. An asymmetric spinnaker or cruising chute is the easier-to-handle version.
- Spreader
- The horizontal struts partway up the mast that push the shrouds outwards, giving them a better angle to support the mast.
- Spring line
- A mooring line running diagonally fore or aft along the dock, stopping the boat sliding back and forth in its berth. Bow and stern lines alone will not do it.
- Spring tide
- The tide with the biggest range, near full and new moon, when highs are higher and lows lower. Nothing to do with springtime — the name comes from the water springing up.
- Squall
- A sharp, short-lived increase in wind, often with rain and a wind shift. Squalls arrive faster than you can reef, which is why you reef when you see one coming.
- Stanchion
- The upright post on deck that holds the lifelines. Not a handhold to swing your weight on.
- Stand-on vessel
- Under the COLREGs, the vessel that maintains course and speed while the give-way vessel keeps clear — until it becomes obvious the other boat is not acting. Read more →
- Starboard
- The right side of the boat when facing forward, marked by a green light at night. Like port, it is a fixed side that does not change with the wind. Read more →
- Stay
- A wire supporting the mast fore and aft — forestay at the front, backstay at the back.
- Stem
- The vertical leading edge of the bow, where the two sides of the hull meet.
- Stern
- The back of the boat.
- Stow
- To put away properly and securely, so it stays put when the boat moves. Anything not stowed is on the floor within an hour of leaving.
- Swell
- Long, regular waves generated by distant wind, which keep running after the local wind has gone. An anchorage can be windless and still uncomfortable if swell wraps into it.
- Swing circle
- The circle the boat sweeps around its anchor as wind and tide change direction — its radius is the rode paid out plus the length of the boat. Fitting yours between the neighbours is the whole art of picking a spot. Read more →
- Tack
- Three meanings. To tack is to turn the bow through the wind; your tack is which side the wind is on (port or starboard tack); and the tack of a sail is its bottom front corner.
- Tender
- Another word for the dinghy. Also describes a boat that heels easily under sail — the opposite of stiff.
- Tiller
- A bar attached directly to the rudder for steering, instead of a wheel. Push it left and the boat turns right.
- Topping lift
- The line from the masthead to the end of the boom that holds the boom up when the mainsail is down.
- Transit
- Two fixed objects ashore lined up one behind the other. If they stay lined up, you are not moving sideways — the cheapest and most reliable check that an anchor is holding. Read more →
- Transom
- The flat surface across the stern of the boat, where the name and often the outboard, boarding ladder or bathing platform live.
- Traveller
- The athwartships track that the mainsheet block slides along, letting you change the boom's angle without changing sail twist.
- Trim
- Adjusting the sails for the wind angle — and also how the boat sits in the water fore and aft.
- Trip line
- A light line from the crown of the anchor to a small float, used to pull the anchor out backwards if it snags on rock or a cable.
- True wind
- The actual wind over the water, as a stationary observer would feel it. What the forecast talks about — the boat feels apparent wind instead.
- Under way
- Not attached to the bottom or the shore — so a boat drifting with the engine off is under way. 'Making way' is different: it means actually moving through the water.
- Upwind
- Towards where the wind is coming from. The direction that takes the longest to get to.
- Vangalso: kicker, kicking strap
- The control pulling the boom down, stopping it lifting and the mainsail twisting off when sailing downwind.
- Veer
- A wind shift clockwise — north to north-east. The opposite, anticlockwise, is backing. Also to veer chain is to pay it out.
- VHF
- The marine radio band used for ship-to-ship and ship-to-shore calls. Channel 16 is the international distress, safety and calling channel, monitored by rescue services.
- Wake
- The disturbed water trailing behind a moving boat. You are responsible for the damage yours does, which is why speed limits exist in anchorages and marinas.
- Warp
- A heavy rope used for mooring, kedging or towing — the British term you will meet in pilot books and marina offices.
- Waypoint
- A position stored in the GPS or chartplotter as a point on a route. A route is a chain of waypoints; the leg between two of them is where the hazards live.
- Weather helm
- The boat's tendency to turn into the wind, felt as constant pull on the wheel or tiller. A little is safe and desirable; a lot means you are carrying too much sail.
- Weigh anchor
- To lift the anchor off the bottom and get under way. 'Weigh' as in lift a weight — nothing to do with 'way' or with weighing anything.
- Winch
- The drum that gives you the mechanical advantage to pull sheets and halyards under load. Turned by a removable handle, which goes back in its pocket rather than over the side.
- Windlass
- The powered winch on the foredeck that raises and lowers anchor chain. It lifts the anchor; it is not a cleat, so the load at anchor goes on a chain stopper and a snubber instead. Read more →
- Windward
- The side the wind is coming from — the exposed side. Leeward is the sheltered one. Both change the moment the wind does, which is what makes them different from port and starboard.
- Yaw
- Swinging from side to side of the intended course. At anchor, a boat that yaws across the wind snatches at its rode and can trip its own anchor. Read more →
- Yawl
- A two-masted rig where the small mizzen mast is aft of the rudder post. A ketch carries its mizzen further forward.
- Zincsalso: sacrificial anodes
- Blocks of soft metal bolted to the shaft, prop and hull that corrode instead of the expensive underwater metal. Once they are half gone, they are replaced. Read more →
Why the vocabulary is worth the effort
Every one of these words replaces a sentence, and does it without ambiguity. “Ease the mainsheet” is three words for “let the rope controlling the big sail out gradually, under control, without letting it run” — and it means the same thing shouted into the wind from the foredeck as it does over a chart table. That precision is not tradition for its own sake. It is what lets a crew who met on Saturday morning work a boat safely by Saturday afternoon.
The anchoring words earn their keep faster than most. Scope, rode, swing circle and holding ground are the four that decide whether your night at anchor is restful or not, and they are the ones that come up in every anchorage conversation. If you only follow one set of links from this page, follow those into our complete guide to anchoring a boat.
And when the words are learned, the last problem is still the same one sailors have always had: you cannot watch your own anchor while you sleep. Safety Anchor Alarm holds the anchor point you set and wakes you the moment the boat leaves its circle — so the vocabulary you needed at 3 a.m. is just “dragging”, and you hear about it early.
Safety Anchor Alarm
GPS-powered anchor monitoring for iOS. Sleep peacefully at anchor knowing you'll be alerted the moment your anchor drags.
Download FreeFrequently Asked Questions
What is the difference between port and starboard?
Port is the left side of the boat when you are facing forward, and starboard is the right side. They are fixed sides that never change, which is why they are used instead of left and right — a crew member facing aft still knows exactly which side you mean. At night, port shows a red navigation light and starboard a green one.
What does windward and leeward mean?
Windward is the side of the boat the wind is hitting; leeward (pronounced 'loo-ard') is the sheltered side away from the wind. Unlike port and starboard, they are not fixed to the boat — they swap sides every time you tack, because they describe your relationship to the wind, not to the hull.
Why is a boat's speed measured in knots?
One knot is one nautical mile per hour, or about 1.85 km/h. The name comes from the old practice of measuring speed by streaming a knotted line astern and counting how many knots ran out in a fixed time. Because 'per hour' is built into the word, saying 'knots per hour' is incorrect.
What is the difference between a rope, a line and a rode?
Rope is the material as it comes off the reel. Once it is on board doing a specific job it is called a line — a sheet trims a sail, a halyard hoists one, a mooring line ties you to the dock. Rode is the specific name for the chain or rope that connects your anchor to the boat.
What is scope in anchoring?
Scope is the ratio between the length of rode you have let out and the total depth of water measured from your bow roller to the seabed at high tide. A minimum of 5:1 is normal for a daytime stop and 7:1 for overnight, meaning five or seven metres of chain for every metre of depth. Too little scope is the most common single cause of an anchor dragging.
Put the words to work
The guides where these terms do the heavy lifting.
Anchoring
Seamanship
Overnight & safety