Sailing Catamaran Glossary
Sailing Catamaran Parts Glossary
A quick-reference guide to the essential components, rigging, and gear found on modern sailing catamarans.
Designed as a practical tool for sailors, crew, and owners – useful for understanding, maintaining, and operating every part of a catamaran with confidence.
Abeam
A direction at a right angle to the boat’s centreline – directly out to the side (athwartships). If something is “abeam,” it’s level with the middle of the vessel on either port or starboard side.
Example: “The buoy is abeam to port.”
Aft
The rear part of the vessel, toward the stern. On a catamaran this includes the aft sections of both hulls and the cockpit/transom area.
Aft Quarter (Quarter)
The rear section of the vessel’s side, roughly between the beam and the stern. The term “quarter” refers to one of the two aft sides: port quarter or starboard quarter.
Example: “The dinghy is tied off the starboard quarter.”
On a catamaran, this area often includes the sugar scoops, davits, and access to stern moorings.
Amidships (or Midships)
The central part of the vessel, halfway between the bow and stern. On a catamaran, “amidships” usually refers to the midpoint of each hull or the middle section of the bridge-deck.
Did you know?: Weight distribution amidships is critical for performance – excess bow or stern loading can affect pitch and bridge-deck clearance.
Anchor
A heavy metal device dropped to the seabed to hold the boat in position. Catamarans normally use a bridle to spread the load between hulls and help the boat to sit steadily on anchor.
Anchor Bridle
A pair of lines that attach to both bows and the anchor chain, distributing load and reducing yaw at anchor.
Asymmetrical Spinnaker
A large, light sail for broad reaching and off-wind sailing. Easier to handle than a symmetrical spinnaker and often flown from a bowsprit.
Athwartships
A direction or alignment running from side to side, perpendicular to the vessel’s centreline.
On a catamaran, this can mean from one hull across to the other – for example, a beam or traveller track runs athwartships. The Windelo 54 owner’s cabin features an athwartships berth.
Catamaran note: The athwartships structure (crossbeams, bridge-deck, and bulkheads) provides key torsional stiffness between the hulls.
Autopilot
An electronic or hydraulic steering system that automatically maintains a set course without manual helm input. On catamarans, it usually controls both rudders through a linkage or hydraulic ram, and is invaluable for long passages.
Backstay
A rigging cable supporting the mast from aft. Most modern catamarans omit it, relying on swept spreaders.
Barber Hauler
A line and block system used to adjust the lead angle of a jib, staysail, or spinnaker sheet – pulling it inboard or outboard to fine-tune sail shape. Very useful on multihulls for optimizing sail trim across wide beam angles. On some boats such as the Outremers, they use a “3D” system so that you can adjust in-out, up-down and forward-aft.
Beam
1. The overall width of the vessel.
2. Structural cross-members connecting the two hulls, adding rigidity.
Bimini / Hard-top
A canvas or rigid cover over the cockpit for shade and weather protection. Often with solar panels and sometimes loungers or even a fly/lounge built in.
Block
A pulley with one or more sheaves (wheels) used to change the direction of a line and reduce load. Found in running rigging systems like mainsheets, halyards, and vangs. High-load blocks are essential on wide-beam cats.
Boom
The horizontal spar at the foot of the mainsail, pivoting on the mast’s gooseneck.
Bow
The forward end of each hull.
Bowsprit
A spar projecting from between bows for flying light wind sails like gennakers or Code 0s. They will have a ring to attach a furler.
Bridle.
A Y-shaped line or stay arrangement, e.g., an anchor bridle or martingale bridle, used to distribute load evenly.
Bridle Mainsheet System (A-Frame)
Instead of a traveller, some catamarans use a bridle mainsheet – a Y-shaped line setup that anchors to starboard and port of the centreline of the boom, distributing mainsheet loads and simplifying boom control. This reduces deck clutter but limits fine traveller adjustment. It protects against accidental gybing well.
Bridgedeck
The deck platform connecting both hulls. It carries the salon and cockpit and affects clearance (slamming resistance).
C-Shaped Daggerboards (C-Foils)
Curved daggerboards shaped like the letter “C,” designed to generate both lateral resistance (to reduce leeway) and vertical lift (to partially raise the hull and reduce drag).
Unlike straight daggerboards, C-shaped foils provide a degree of hydrofoil assistance without fully lifting the boat out of the water. They’re seen on some modern high-performance multihulls such as the HH52 and Rapido 53X.
Advantages: Improved speed and stability, reduced pitching, and better efficiency at high speeds.
Trade-off: More complex to build and maintain; their curved profile requires precise engineering and careful handling when raising or lowering.
Cleat
A metal or composite fitting used to secure lines such as mooring lines or halyards.
Clew
The lower aft corner of a sail, where the foot and leech meet. The sail’s outhaul (main) or sheet (jib) usually attaches here.
Clutch (Rope Clutch)
A deck-mounted line-holding device that grips a rope under load, allowing lines to be tensioned on a winch and then locked off. Found on halyards, reefing lines, and sheets, often leading to the helm on catamarans for single-handed control.
Code 0
A large, flat light-air sail between a genoa and a gennaker in design; great for close-reaching to reaching in light winds.
Code 55
A flatter, higher-load reaching sail built for tighter apparent wind angles – for when you’re close-reaching.
On catamarans, it replaces a genoa for high-speed close reaching, maintaining shape under high loads.
Design note: Stronger luff cable and higher-modulus cloth than the Code 65; optimized for apparent wind pressure and minimal stretch. North Sails do a good range.
Code 65
A medium-light reaching sail designed for angles between the Code 0 and the Code 55.
It’s slightly fuller than a Code 55, maintaining good shape as wind angles open up.
Material: Medium-weight laminate or nylon for durability and controlled stretch.
Code 3
A reaching sail for moderate to stronger breezes.
Often built from durable laminate. Being heavier, you can leave these sails up furled longer. Incidence have a good example.
Code 5
A downwind asymmetric sail suited for reaching and broad reaching.
Good for heavier-air reaching when stability and control are more important than maximum lift. Commonly set on its own furler forward of the bowsprit.
Cockpit
The working and lounging area aft of the salon, where the helm, winches, and sheets are controlled.
Cunningham
A line used to tension the luff of the mainsail and control sail shape by adjusting draft position. On a catamaran, this helps flatten the large mainsail in higher winds without over-tightening the halyard.
Daggerboard
A retractable board in each hull that improves upwind performance and reduces leeway. Not all cats have them.
Davits
Lifting arms or a frame (often on the stern) used to hoist and stow the tender above the waterline.
Deck
The walking surface covering the hulls, foredeck, cockpit, and bridge-deck.
Dual-Speed Winch Controls
Winches with two selectable gear ratios – one for fast retrieval (low load) and one for slow, powerful grinding (high load). Electric versions often have variable speeds; essential for handling large catamaran sails efficiently.
Emergency Tiller
A manual steering arm that can attach directly to the rudder post if the main steering system fails.
EPIRB (Emergency Position Indicating Radio Beacon)
A satellite distress beacon that transmits the boat’s location to rescue services when activated. Mounted near the helm or in the grab-bag – mandatory offshore safety equipment.
Fenders
Inflatable or foam bumpers used to protect the hull from docks or other boats.
Floating Line
A rope made of buoyant material that floats on water, used for tying off on rocks, mooring, towing, or safety retrieval. Prevents fouling in twin props or rudders, which is important on catamarans.
Foot (of sail)
The bottom edge of a sail between the tack and clew.
Foredeck
The forward deck area, typically between the bows or ahead of the salon. Often includes trampolines or sun-pads.
Forestay
A forward-running cable that supports the mast and carries the luff of the jib or genoa.
Gennaker
A hybrid sail between a genoa and a spinnaker, used for reaching and easy to furl.
Genoa
A large overlapping headsail whose foot extends past the mast for extra area.
Gooseneck
The pivoting joint connecting the boom to the mast.
Gybe
A sailing manoeuvre in which the stern of the boat passes through the wind, causing the mainsail and boom to swing from one side to the other. It’s the downwind counterpart to tacking.
On a catamaran, gybing must be done carefully due to the wide boom arc and large sail area – controlled gybes often use the mainsheet and traveller to control the boom across the gybe (or using the bridle mainsheet system).
NB: Always bring the mainsail toward the centreline before initiating a gybe to reduce shock loads on the rig and prevent accidental (uncontrolled) gybes.
Halyard
A rope or line used to raise and lower sails. Examples: mainsail halyard, jib halyard.
Hatch
A watertight opening in the deck or cabin top for ventilation or access below.
Head
1. The top corner of a sail.
2. Marine toilet.
Helm
The steering position – wheel or tiller – wheels are often elevated on catamarans for better visibility.
Hull
One of the two main bodies of a catamaran that provide buoyancy and hydrodynamic shape.
Jib
A non-overlapping foresail, often self-tacking for easy handling.
Jib Luff
The forward edge of the jib, attached to the forestay or furling gear.
Lazybag (Stackpack)
A sail bag attached to the boom into which the mainsail drops when lowered, supported by lazy-jacks.
Leech
The trailing edge of a sail, from head to clew. Adjusted by sheet tension to control sail twist.
Leeward (pronounced LOO-erd)
The side or direction away from the wind – the “downwind” side of the vessel.
On a catamaran, the leeward hull is the one opposite the wind, often carrying most of the load when sailing upwind.
Example: “The tender engine is on the leeward side.”
Tip: When manoeuvring or anchoring, always consider how the boat will drift leeward with the wind. Careful anchoring and sailing off a lee shore.
Long Floating Line
A buoyant line used for towing or rescue; floats on the surface to avoid propeller fouling.
Luff
The forward edge of a sail (attached to mast or stay). Also a verb – when a sail flaps or spills wind.
Main Halyard
The halyard used to hoist the mainsail.
Mainsail
The primary and usually largest sail, attached to the mast and boom.
Mainsheet
The control line that trims the boom and mainsail’s angle to the wind.
Martingale
A rigging bridle under the bowsprit or between hulls that supports the bowsprit under load.
Mast
The tall vertical spar that supports sails and rigging.
Mooring Lines / Warps
Ropes used to secure the boat to a dock, pontoon, or buoy.
Nav Display (Navigation Display)
The electronic screen showing navigational data such as chartplotter maps, wind, depth, AIS, and autopilot information. Typically mounted near the helm on a catamaran.
Off the Bow
A direction reference meaning ahead of the vessel but not directly forward – typically 10° to 45° off the centerline.
Example: “There’s a vessel 30 degrees off the port bow.”
Used in navigation, collision avoidance, and lookout reporting.
On the Quarter
When something (like wind or waves) comes from behind and to the side – roughly 45° off the stern.
Example: “We’re running with the wind on the starboard quarter.”
A comfortable sailing angle for catamarans because it combines downwind power with stability.
Paddle Wheel (Boat Speed Sensor)
A small impeller mounted through the hull that measures boat speed through water, feeding data to onboard instruments for True Wind Speed (TWS) and True Wind Angle (TWA) calculations.
Your nav system will also monitor GPS-based speed (SOG). The difference will give you the current speed.
Tip: make sure you clean regularly, especially if you spend prolonged periods in marinas.
Parasailor
A downwind sail similar to a spinnaker but with a vented “wing” section that stabilizes airflow; easier to handle short-handed. Also “Wingaker”
Port
The left-hand side of the vessel when facing forward.
Reefing Cringle
A reinforced eyelet in the sail for passing lines during reefing to reduce sail area.
Reefing Line
The line used to pull down a section of the sail during reefing.
Reefing Tack Hook
A metal hook or fitting (usually mounted near the gooseneck on the mast) used to secure the forward reefing point – the tack cringle – of the mainsail when reefing. It holds the sail’s new tack firmly in place after reefing taking the load from the halyard.
Reefing Tack Line/Strap
A line used to pull down and secure the tack (forward lower corner) of the mainsail when reefing, sometimes led aft to the cockpit for single-handed operation. It replaces the tack hook. On some cats (Nautitech 40, ORC57) this is simply a strap that you deploy through the cringle at the mast.
On many new catamarans, single-line reefing systems combine the tack line and reefing line into one continuous line for safety and simplicity. The downside is that these can be long (especially the third reef).
Rig / Rigging
The entire system of mast, stays, shrouds, halyards, and sheets used to set and control sails.
Rotating Mast
A mast designed to pivot slightly around its base to align with airflow, reducing drag and increasing sail efficiency. Common on performance and racing catamarans.
Trade-off: More efficient but mechanically complex; requires careful rig tuning.
Rudder
A vertical steering blade, typically one on each hull, linked to the helm.
Running Rigging
All moveable lines used to control sails and spars – includes halyards, sheets, reefing lines, vangs, and control lines. On catamarans, running rigging is often led aft to the helm for ease of handling.
Saildrive
A compact propulsion system that combines the gearbox and propeller shaft in a single unit extending from the engine through the hull. The propeller sits directly below the engine, reducing vibration and improving efficiency.
On catamarans, saildrives are common because they simplify installation in each hull, allow for twin-engine layouts, and provide smooth, quiet operation.
Maintenance tip: Check and replace saildrive seals regularly to prevent water ingress and check for galvanic corrosion. Check your sacrificial anodes regularly.
Self-Tacking Jib
A jib on a curved track that tacks automatically, simplifying short-handed sailing.
Shaftdrive
A more traditional propulsion setup in which the engine’s gearbox drives a long shaft running aft through the hull to an external propeller.
Less common on modern production catamarans (where saildrives dominate) but still found on some models like the Max Cruise Marine 45 and Windelo 54 (electric hybrid). Shaft drives can handle higher torque, are more robust and are easier to service for long-range cruisers.
Tip: Ensure proper alignment and shaft seal maintenance to prevent vibration or leaks.
Sheet
A rope controlling the trim of a sail (e.g., jib sheet, mainsheet).
Single-Line Reefing
A reefing system allowing both luff and leech of the sail to be reefed with a single control line.
Spinnaker
A large, light, symmetrical downwind sail used for running before the wind.
Spinnaker Halyard
A dedicated halyard used to hoist and lower the spinnaker (or gennaker). Usually exits the mast near the top and leads down to a winch.
Tip: Keep it separate from the main halyard to avoid chafe and tangles when dousing or furling downwind sails. You can use this halyard for lifting jobs at anchor.
Stanchion
A vertical post supporting lifelines or guardrails around the deck for crew safety.
Standing Rigging
All fixed wires or rods that support the mast, such as forestay, shrouds, and backstay (more common on monohulls). Catamarans often have wide shroud bases for lateral stability and high compression loads.
Starboard
The right-hand side of the boat when facing forward.
Stay / Stays
Standing rigging wires supporting the mast. Include forestay, backstay, and side shrouds.
Staysail
A smaller sail set between the mast and forestay; good in heavy air or as an inner headsail.
Stern
The rear end of the vessel, often where the cockpit or sugarscoops are located.
Sugar Scoops
Stern extensions or swim platforms on each hull, extending the waterline length and providing water access and dinghy boarding.
T-Rudders
Rudders with horizontal hydrofoil surfaces at the base, forming a “T” shape. The vertical section steers the vessel as usual, while the horizontal foil generates lift to reduce drag, control pitch, or even lift the hull partly out of the water.
On high-performance or foiling catamarans, T-rudders help stabilize fore-and-aft motion (pitching) and improve speed by decreasing hull drag.
Trade-off: They add mechanical complexity and are more exposed to damage in shallow water or when grounding, so cruising catamarans typically use conventional spade rudders instead.
Tack
1. The lower forward corner of a sail.
2.To change direction by turning the bow through the wind.
Tell-Tales
Small strips of yarn or ribbon attached to sails or shrouds to show airflow. Properly aligned tell-tales indicate optimal sail trim – critical for fine-tuning large sails on a catamaran.
Tender (Dinghy)
A small auxiliary boat used for shore trips, usually stored on davits or the aft platform.
Topping Lift
A line running from the masthead (or near the mast top) to the end of the boom, supporting it when the mainsail is lowered. It keeps the boom from dropping into the cockpit and can also fine-tune the boom’s height when reefing or adjusting the mainsail.
Traveller
A sliding track system that changes the attachment point of the mainsheet, to fine-tune sail trim. Position to windward when close-hauled and to leeward when on a broad reach or to spill power from the sail.
Trampoline
A netting area between hulls at the bow that allows water drainage and lounging space. Also called nets, tramps.
Vang (Boom Vang)
A tackle or hydraulic strut controlling the vertical movement of the boom and shaping the mainsail. Not often seen on a catamaran. You may see one on a Leopard.
VHF (Very High Frequency) Radio
A marine communication system used for short-range ship-to-ship and ship-to-shore communication, including distress calls on channel 16. Often paired with AIS and GPS on modern helm displays.
Warps
See Mooring Lines – longer or heavier lines used for mooring or towing.
Wind Sensor – Masthead
An electronic sensor mounted at the top of the mast that measures Apparent Wind Speed (AWS) and Apparent Wind Angle (AWA). The data feeds the navigation display or sailing instruments to show wind direction and speed relative to the boat’s heading.
On catamarans, masthead wind sensors are critical as you need to monitor apparent wind closely for reefing.
Tip: Regularly clean and calibrate; mast vibration and salt build-up can distort readings.
Windlass
A powered device (electric or hydraulic) used to raise and lower the anchor and chain. Usually mounted on the foredeck or in an anchor locker, with foot switches or helm controls.
On catamarans, the windlass must handle higher loads due to larger anchors and twin-hull windage. It often works with an anchor bridle to take the strain off the windlass when at anchor.
Tip: Regularly rinse with fresh water and inspect electrical connections – salt corrosion and chain twist are common maintenance issues.
Winch
A geared mechanical drum used to haul or ease lines under load, e.g., sheets, halyards.
Windward
The side or direction from which the wind is blowing – the “upwind” side of the vessel.
On a catamaran, the windward hull is the one facing the wind and may lift slightly under sail on high-performance designs.
Example: “Throw the windward aft line to the dock.”
Note: Being aware of windward helps with sail trim, helming, and right-of-way rules at sea.
Wingaker (Light-Air Spinnaker)
A light-air downwind sail (asymmetrical spinnaker) with a vent optimised for very light downwind conditions.
Practical Tips
1. Boat Familiarisation: Walk around your catamaran and label stuff where needed (eg reefs 1, 2, 3 on the clutches)
2. Maintenance Mapping: Group them into categories (rigging, deck gear, sails, safety, anchoring) and schedule checks.
3. Sailing Vocab: Use as a tool for charter guests or team sailing. Make a simplified version for your crew.