Aft
The rear of the boat.

Aft cabin
Sleeping quarters at the aft or rear section of the boat (sometimes called a mid-cabin when located beneath the helm).

Alee
The side of a boat or object away from the direction of the wind or Leeward side.

Aloft
Above deck in the rigging.

Amidships
Centre section of a boat.

Anchor
A heavy (usually) metal object, of various shapes, on a strong rope or chain connected to the boat, that is dropped from a boat into the water to prevent the boat from moving away.

Anchor roller
A device consisting of a wheel within a framework that is designed to guide an anchor when it is lowered or raised. Sometime also referred to as a bow roller.

Anchorage
A location intended or suited for anchoring.

Anti-fouling paint
A special ablative paint applied to a boat’s hull to reduce marine growth.

Apparent wind
The direction and velocity of wind as felt in a moving boat.

Astern
The direction toward or beyond the stern.

Athwart
Perpendicular to a boat’s centreline.

Aweigh
An anchor that is off the bottom.

Backing down
Manoeuvring in reverse, e.g. when offshore fishing while attempting to land a fish.

Backstay
A support for the mast to keep it from falling forward.

Bail
To remove water with a bucket or pump.

Bait station
Area on a fishing boat for preparing bait.

Baitwell
Compartment on a fishing boat for holding live bait.

Ballast
Weight added to a boat to increase displacement. Typically added to the bottom of a boat to improve stability.

Beam
Measurement of a boat at its widest point.

Bear off
To turn away from the wind.

Bearing
Direction to an object.

Beating
Sailing upwind.

Berth
A place to sleep aboard a boat. Also a position at a port or marina where a boat may be secured.

Bilge
Lowest section inside a boat’s hull where water collects.

Bimini
A canvas cover over the helm or cockpit area.

Bitt
Vertical post extending above the deck to secure docking lines.

Boom
A spar attached to a sail at its foot.

Bow
Forward portion of a boat.

Bow eye
A stainless-steel U-bolt on a boat’s bow stem used to secure tow lines or trailer winch hooks.

Bow stop
Rubber blocks on a boat trailer into which the boat’s stem rests.

Bowrider
A runabout boat with open-bow seating.

Bowsprit
A spar or section extending forward of the bow on a boat.

Breakaway lanyard
Emergency safety cable on a boat trailer that activates trailer brakes in the event the trailer becomes detached from the tow vehicle while underway.

Bridge clearance
Distance from waterline to the underside of a bridge. (MHWS)

Bulkhead
Wall in a boat that often bears weight and supplies hull support.

Bunks
Beds on a boat. Also, long carpeted sections of a boat trailer that support the boat’s weight.

Buoy
An anchored floating object, often used as a navigation aid or to mark a mooring spot.

Burgee
Small flag that bears a yacht club’s symbol.

Camber
Curvature of a sail, or curvature of anything else such as a boat.

Can buoy
Cylindrical navigation buoy with a flat top.

Capsize
To flip a boat over.

Capstan
A winch used for hauling heavy objects such as anchors.

Cast off
To unfasten all lines in preparation for departure.

Casting platform
Elevated deck clear of obstruction used by anglers to make casts.

Catamaran
A twin-hulled boat.

Cavitation
Aeration causing Inefficient low-pressure pockets on propellers which form bubbles that collapse against the blades resulting in premature wear.

Centre console boat
Boat with the helm station located amidships with walk-through space around the perimeter of the boat.

Centreboard
A keel-like pivoting device.

Channel
The navigable portion of a waterway.

Chart plotter
Electronic navigation device that displays charts for use in plotting a course.

Chart recorder
An electronic depth sounder that records bottom structure data on paper.

Charts
Paper or electronic navigation maps.

Chine
Portion of the hull where the bottom and sides intersect (can be rounded or angled).

Chopped fibreglass
Fibreglass strands cut and simultaneously mixed with resin then applied to a boat mould by using a chopper gun.

Chumming
More commonly known as burley in Australia, it is the act of placing fish parts, or other matter in the water to attract fish.

Class I hitch
Trailer hitch with a weight-carrying capacity up to 900 kgs.

Class II hitch
Frame-mounted trailer hitch with a weight-carrying capacity of up to 1200 kgs.

Class III hitch
Frame-mounted trailer hitch with a weight-carrying capacity of up to 1600 kgs.

Class IV hitch
Frame-mounted trailer hitch with a weight-carrying capacity of up to 3500 kgs.

Clears / curtains
Attachable front and side clear enclosures that protect the helm area from weather.

Cleat
Hardware piece on a boat or a dock to which lines are attached.

Clew
The after-most corner of a sail.

Close-hauled
Sailing as close to the wind as possible.

Coaming
A raised edge.

Cockpit
Deck space for the crew of a boat.

Come about
To tack or change heading relative to the wind.

Companionway
Passageway from the deck to the below deck area.

Convertible
A fishing boat style, usually with a flybridge and a full cruising salon.

Coring material
Any of a variety of lightweight materials used between layers of fiberglass laminates to add strength.

Corinthian
Amateur yachtsman.

Counter rotation
The act of two propellers spinning in opposite directions, often on a single shaft or on a multi engine vessel.

Coupler
Component on a boat trailer that connects to the tow ball of the tow vehicle.

Course
Direction in which a boat is steered.

Cruiser
A boat with overnight accommodations.

Cuddy cabin
Belowdecks accommodations in the bow area for overnighting and stowage.

Cure
Hardening process for resin-soaked fibre glass laminates.

Cutter
Single-masted sailboat similar to a sloop. Single masted but with two headsails.

Daggerboard
A keel-like device that is manually raised and lowered vertically without using a hinge.

Davit
A small crane used to hoist a boat, dinghy or other object.

Day sailing
To go sailing for a few hours on a vessel.

Dead ahead
Directly ahead of the bow.

Deadrise
Degrees of V-shape hull angle measured at the transom of planing powerboats.

Deep-V
A hull shape characterized by a sharp deadrise.

Depth sounder
Electronic sonar device that displays water depth.

Deviation
The amount of error from displaying magnetic north in a boat’s compass caused by the boat’s own magnetic interference.

Differential GPS (DGPS)
A highly accurate global positioning system (GPS) that utilises a differential radio beacon and receiver to compute and correct the error of all visible satellites sending data to a conventional GPS unit.

Dinette
A small dining area usually consisting of a table and facing bench seats. It can often be converted into a berth.

Dinghy
A small sailboat often raced that can be sailed on and off a beach. Also can be a tender to a larger boat.

Direct drive
An engine configuration in which the drive shaft runs in a straight driveline from the crank shaft through the bottom of the hull.

Displacement
The weight of water displaced by a hull. Also the weight of the ship including cargo, passengers, fuel, water, stores, dunnage and such other items necessary for use on a voyage.

Displacement hull
A hull shape designed to run through water rather than on top of it in the manner of a planing hull.

Downrigger
A gunwale-mounted weighted line device used for deep-water trolling.

Draft
Vertical distance a boat penetrates the water.

Drogue
A parachute-like sea anchor or a device trailed behind to slow a boats movement through the water.

Dry weight
Weight of the boat without fuel and fresh water.

EPIRB
Acronym for emergency positioning indicating radio beacon. When this electronic device is activated it transmits a radio signal with user registration data and positioning information to a network of satellites that assist the emergency services in conducting an emergency rescue.

Fathom
Nautical depth measurement equalling six feet (1.8 metres).

Fender
A cushion or bumper used to protect the hull sides of a boat. Often cylindrical or round.

Fetch
Area of ocean or lake surface over which the wind blows in an essentially constant direction, thus generating waves. The term also is used as a synonym for fetch length, which is the horizontal distance over which wave-generating winds blow.

Fibreglass
Glass fibres either loose or woven used in the construction of vessels.

Fighting chair
A fix-mounted chair with a footrest used to help land large gamefish on bluewater fishing boats.

Fin keel
A keel shaped like the fin of a fish that is shorter and deeper than a full-length keel.

Fishfinder
Electronic device that uses sonar to locate and display fish on a monitor.

Fix
The position of a boat recorded in coordinates or bearings.

Flare
A pyrotechnic device used to indicate distress. Also the angle at which a ship’s hull plate or planking departs from the vertical in an outward direction with increasing height.

Flat-bottom boat
Type of boat or hull shape with very little or no deadrise.

Following sea
Wave pattern running in the same direction as the boat.

Foot
The bottom edge of a sail.

Fore
Towards the front of a boat.

Foredeck
Forward part of the main deck.

Founder
To sink.

Four-stroke engine
An internal combustion engine that takes four cycles or strokes of the piston to complete its power phase.

Frame-mount hitch
Hitch fastened to the frame of a tow vehicle.

Freeboard
Vertical distance between the waterline and the top of the hull side.

Furling
Rolling or folding a sail on its boom. Furling reducing sail area by mechanical means either its mast or forestay.

Gaff
A metal pole with a hooked end used to lift a fish from the water. Also a pole or spar that holds the upper portion of a four-sided sail.

Galley
The kitchen area on a boat.

Gelcoat
A combination of resin and pigment that comprises the smooth outside coating of a fibreglass boat.

Genoa
An overlapping jib.

Genset
Another name for a petrol (or diesel) powered electric generator.

Give way
Give way to other traffic.

GPS
Acronym for global positioning system.

Gross vehicle mass (GVM)
The GVM is the maximum loaded weight of a rigid vehicle while driving on the road.

Gross combination mass (GCM)
The GCM is the maximum loaded weight of the towing vehicle and any trailer, or trailers, being towed while driving on the road.

Gross trailer mass (GTM)
The GTM is the maximum mass on the axle(s) of a trailer when fully loaded while driving on the road.

Gunwale
The upper edge of the side of a boat.

Gybe
Also spelled jibe. To change the course of a boat so that the boom swings over to the opposite side. Also described as to tack downwind

Halyard
Line used to hoist a spar or sail.

Harbour master
The person at a harbour that is in charge.

Hard chine
A sharp-angle at the intersection of the hull’s side and bottom.

Hard over
Turning the steering wheel or tiller all the way in one direction.

Hard-top
A large fiberglass roof or platform over the helm area.

Hatch
A deck opening.

Hauling
To lift a boat from the water.

Hawse pipe
Fittings in the deck or gunwale through which the anchor rode or dock lines run.

Head
Toilet facilities or room where they are located.

Head seas
Waves coming from the direction a boat is heading.

Heading
The direction a boat is pointed.

Headsail
Any sail set forward of the mast, sails set off the forestay.

Headway
Forward motion of a boat in the water.

Heave
To pull on a line. Also to throw a line.

Heaving to
Setting the sails so the boat makes little headway.

Heel
To temporarily tip or lean to one side.

Helm
Area of a boat where operational controls are located.

Hike
To lean out on the windward side of a sailboat to achieve optimal speed by offsetting heeling.

Hitch
Steel framework on a tow vehicle used to hook up a trailer.

Hitch ball
The ball-shaped component of the hitch that fits into the trailer coupler. Also known as a tow ball.

Holding tank
Storage tank for grey or black water.

Hull
The structural body of the boat that rests in the water.

Inboard engine
An internal combustion engine often mounted amidships that runs a drive shaft through the hull bottom.

Inboard/outboard (I/O)
See stern drive.

Inflatable
Capable of being inflated either with air or another gas.

Inflatable boat
A type of boat with air chambers into which air is pumped either manually or automatically for buoyancy.

Inner liner
Smooth-finished, molded fibreglass structure adjacent to the inside portion of the hull.

Inverter
Device that changes 12VDC or 24VDC to 240VAC.

Jack plate
A mounting device for an outboard motor that enables operators to vertically raise or lower the motor.

Jet boat
A boat powered by an engine with a water-pump used to create propulsion.

Jib
Triangular sail projecting ahead of the mast.

Jibe
See gybe.

Keel
The bottom-most portion or longitudinal centreline of a hull.

Ketch
A sailboat similar in appearance to a yawl with a tall main mast and a shorter mizzen mast ahead of the rudder post.

Kicker motor
A small auxiliary outboard motor.

Kill switch
A switch with a lanyard that automatically shuts off an engine if disconnected.

Kite fishing
A technique that involves attaching a fishing line to a kite to present bait at a distance from the boat.

Knot
Speed measured in nautical miles per hour (equals exactly 1.852 km/h).

Laminate
A single layer of material used in multi-layered construction.

Lamination schedule
A list of the sequential layers of materials used in fibreglass construction.

Latitude
Geographic distance north or south of the equator expressed in degrees and minutes.

Lee
Direction toward which the wind blows.

Lee side
The side of an object that is sheltered from the wind.

Leeway
To slip sideways downwind while moving forward.

Lifeline
Safety lines on deck that are grabbed to prevent falling overboard.

List
A continuous lean to one side due to improper weight distribution.

Livewell
Compartment on a fishing boat designed to keep fish or bait alive.

LOA
Length overall; the distance between the most forward part of the boat and the most aft part.

Locker
A stowage compartment.

Longitude
Geographic distance east or west of the prime meridian expressed in degrees and minutes.

Luff
The leading edge of a sail.

Mainsail
The largest regular sail on a sailboat.

Make fast
To secure a line.

Marinisation
The addition of marine components to automotive engines.

Mast
Vertical spar that supports sails.

MAYDAY
A radio distress call.

Mean high water springs (MHWS)
Mean high water springs is the highest level that spring tides reach on the average over a period of time.

Midships
Location near the centre of a boat.

Mizzen mast
A shorter mast located aft of the main mast on a yawl or ketch.

Modified-V hull
A modification of the deep-V hull shape with a deadrise of less than 20 degrees.

Mould
A hollow reinforced cavity that is the mirror-image or reverse-image of the boat and into which fibreglass is laid up.

Monohull
A boat with a single hull.

Mooring
Permanent ground tackle fixed to a buoy that boats can tie to.

Motorsailer
A hybrid boat that has sails and powerful engines.

Motoryacht
A large powerboat greater than 12 metres with luxurious interior accommodations for long-range cruising.

Multihull
A boat with more than one hull.

Nautical mile
A distance of 1.82 kilometres.

Nun buoy
Conical navigation buoy marking the right hand side of a channel leading into a harbour: green in Australian waters.

Outboard bracket
Support device for mounting outboard engines that extends aft of the transom.

Outboard motor
Internal combustion engine mounted at the transom that incorporates a gearbox and propeller.

Outdrive
The lower unit of a stern-drive motor that houses the drive gears and to which the propeller fastens.

Outrigger
Poles designed to spread out fishing lines and keep them from tangling while trolling.

Overboard
Over the side of a boat and into the water.

Personal flotation device (PFD)
A safety vest or jacket capable of keeping an individual afloat.

Personal watercraft (PWC)
Small ‘jetski’ type vessel.

Piling
A post driven into the ground below the waterline to support a pier.

Pilot house
A fully enclosed helm compartment.

Pitch
Theoretical distance a propeller would travel in one revolution. Also an up and down movement of the bow of a boat.

Planing hull
A boat hull designed to ride on top of the water rather than plowing through it.

Plot
To plan a navigation course using a chart.

Poling platform
Small elevated stand on a flat boat used by a fisherman to silently push the boat through shallow water with a pole and scout for fish.

Pontoon boat
A type of boat with a flat deck attached to airtight flotation tubes or logs.

Port
The left side of a boat when facing the bow.

Power catamaran
A multi-hulled powerboat with two identical side-by-side hulls.

Power cruiser
A powerboat with overnight accommodations

Propeller
A rotating multi-blade device that propels a boat through the water.

Pulpit
Forward deck and railing structure at the bow of a boat.

PWC
See personal watercraft.

Quarter
The after side of a boat from amidships to stern.

Quartering
The practice of aiming the boat’s bow at a 45-degree angle to oncoming waves.

Quarters
Living and sleeping areas of a vessel.

Racer
A sailboat designed primarily for speed and competition with a minimum of built-in creature comforts.

Racer/cruiser
A fast sailboat designed with comfortable accommodations.

Radar
Electronic device using high frequency radio waves to detect objects and display their positions on a monitor.

Range
Distance a boat can travel at cruising speed on a tank of fuel. Also describes the distance between high tide and low tide.

Reach
To sail across the wind.

Ready about
Last warning given by a helmsman before tacking and turning the bow into the wind.

Receiver box
Part of a hitch that receives and holds the hitch bar or shank.

Receiver hitch
A hitch with a receiver from which a hitch bar or shank can be removed.

Resin
Liquid substance used in fibreglass composite construction that bonds the elements together.

Reverse chine
A chine that angles downward from the hull designed to direct spray out and away from the boat.

RIB (rigid inflatable boat)
An inflatable boat fitted with a rigid bottom.

Rigging
The system of ropes, cables and chains, which support a sailing ship or sail boat’s masts and sails.

Rocket launcher
A device designed to hold fishing rods on a boat. Often incorporated into a bench seat, the coaming or other areas of a boat.

Rod holder
Device designed to safely and securely hold fishing rods either vertically or horizontally.

Rode
Line, chain, cable or any combination of these used to connect the anchor to the boat.

Rolled-edge skiff
A fishing boat designed to run in coastal waters constructed of a simple, one-piece fibreglass hull without a top deck and characterized by rounded top edges without true gunwales.

Roller trailer
A trailer outfitted with rollers instead of bunks.

Rubrail
Protective outer bumper that runs around the boat at the point where the top deck meets the hull.

Rudder
Underwater fin mounted below the hull near the stern that controls boat steering.

Runabout
A kind of small watercraft usually driven by an outboard engine.

Running lights
Required navigation lights that a vessel underway uses at night to indicate position and status.

Running rigging
Lines used in the setting and trimming of sails.

Safety chains
Legally mandated chains that connect the trailer to the tow vehicle as a safety measure in case the coupler detaches.

Safety harness
A harness worn by a boater attached to the boat with a tether to reduce the chances of going overboard.

Sag
To slide or drift off course. Also the term given to the stress a boats hull experiences that causes the keel or centre of the boat to bend downwards.

Sail plan
Arrangement of sails on a boat.

Sailboat
A boat that is at least partially propelled by capturing the force of wind in sails.

Salon
Full-sized cabin or lounge area aboard a substantial yacht or motor cruiser.

Saltwater fishing boat
Any fishing boat used in the ocean or coastal waters that is specially equipped to handle the saltwater environment.

Schooner
A large sailboat with two or more masts where the foremast is shorter than aft mainmast.

Scope
The ratio of anchor rode to vertical depth.

Scud
To run before the wind in bad weather.

Scuppers
Gravity fed drain in a boat to allow water to drain out and overboard.

Scuttle
To cut holes or open ports to purposely let water in to make a boat sink.

Scuttlebutt
Gossip. So named after a water cask around which sailors used to gather and drink.

Sea anchor
Also known as a drift anchor, para-anchor or boat brake. Streamed from a boat to stabilise the vessel and to limit progress through the water (see also Drogue).

Sea cock
Through-hull fitting with a valve between the interior and the exterior of the boat.

Seaworthy
Safe to put to sea.

Sedan cruiser
A type of large boat equipped with a salon and a single helm station on the same level.

Self-bailing
Drains water overboard automatically.

Semi-displacement hull
A hull shape with soft chines or a rounded bottom that enables the boat to achieve minimal planing characteristics.

Sheer
Line of the deck or gunwale from bow to stern as viewed from outside the boat.

Sheet
Line used to trim a sail, usually made from rope.

Shroud
Mast support rigging, usually a wire, that runs from the mast to the side of the boat.

Side console
A helm station offset to the side of the boat, rather than in the centre.

Skeg
A fin or vertical projection below the hull that provides directional stability. The term also applies to the lowest point on an outboard motor or the outdrive of an inboard/outboard engine.

Slip
A boat berth between two piers or floats. Also to ‘slip’ a boat implies hauling the boat out of the water.

Sloop
A single-masted sailboat in which the mast is set forward of midships.

Sole
The deck floor.

Sonar
A method to locate objects and determine distance by transmitting sound waves through water and measuring the time it takes the echo to bounce back. Used in depth finders and fishfinders.

Sounding
Charted water depth.

Spar
A pole of wood, metal or lightweight materials such as carbon fibre used in the rigging of a sailing vessel to carry or support its sail. These include booms and masts, which serve both to deploy sail and resist compressive and bending forces, as well as the bowsprit and spinnaker pole.

Sportfisher
A type of bluewater fishing boat, often with sleeping cabins, cooking facilities and many dedicated fish-fighting features.

Spring line
A docking line to control fore and aft movement.

Stand by
An order to crewmen to be ready.

Stand on
Maintain course and speed.

Standing rigging
The shrouds and stays that support the mast but are not adjusted while working a boat.

Starboard
The right side of the boat looking toward the bow.

Stateroom
A room with sleeping quarters.

Stay
Wire, rod or other rigging that runs fore and aft of the mast.

Stem
The most forward section of the hull.

Step
Socket that holds the base of the mast.

Stepped hull
A high-performance hull design with lateral notches.

Stern
Aft portion of a boat.

Stern drive
Propulsion system composed of an inboard engine connected to a steerable drive unit extending through a cut-out in the transom.

Stow
To put an object away onboard a boat.

Strakes
Small linear protrusions that run longitudinally on both sides of the keel to give a planing hull lift and lateral stability.

Stringers
Internal beams and braces that give a fibreglass hull structural support.

Surge brakes
Hydraulic trailer brake system activated by the sudden inertia of a trailer pushing against the tow vehicle during a hard stop.

Swamp
To fill a boat with water.

Sway
Side-to-side wandering of a trailer under tow.

Swim platform
A wide platform at the transom, often equipped with a ladder to help ease the effort of reboarding after going into the water.

Tack
The lower corner of a sail. Also for the side of a sailing craft from which the wind is coming while underway.

Tender
See dinghy.

Through-hull
A fitting or object that goes all the way through a hull.

Tiller
A bar connected to the rudder and used to steer the boat.

Tiller handle outboard
A small handle that extends from the outdoor engine by which the vessel is steered. Can also be the handle that attaches to the rudder on a sailing craft for the same purpose.

Tongue jack
Adjustable jack on the trailer tongue that raises and lowers the coupler.

Tongue weight
The measurement of trailer weight when loaded with a boat on the hitch ball.

Topsides
The hull above the waterline.

Tow rating
Maximum weight a vehicle is rated to tow.

Trailer tongue
Forward portion of a trailer where the coupler is mounted.

Trailer winch
Device that uses a crank and cable to assist in launching and retrieving a boat.

Transducer
An electronic sensing device mounted in a boat’s bilge or at the bottom of the transom to provide data for a depth sounder.

Transom
The rear section of the hull connecting the two sides.

Transom shower
A hose and shower head located near the transom that draws from a fresh water supply.

Trim
The way a boat floats in relation to the horizon.

Trim tabs
Hydraulically adjusted horizontal plates located on the bottom of the transom that control the trim angle of a boat at speed.

Trimaran
A type of boat with three side-by-side hulls.

Trolling
To fish by towing an array of baited lines or lures behind the boat.

True wind
Direction and velocity of wind measured at a fixed point.

Tuna tower
Tall aluminium tower used for spotting fish in the distance.

Two-stroke engine
An internal combustion engine that takes two cycles or strokes of the piston to complete its power phase.

Underway
A boat is said to be ‘underway’ if it is not aground, not at anchor or secured to the dock.

Utility boat
A type of small boat used to gain access to waters too small to be entered by a larger vessel, or to affect repairs to a larger craft.

UHF
Ultra High Frequency: A bandwidth designation commonly used by marine radios, however VHF is preferred.

V-berth
A bed or berth located in the bow that has a V-shape.

V-drive
Propulsion system where the drive shaft initially runs forward into a gear box and then runs aft and down through the hull. The driveline forms a V-shape with the gear box at the pivot point.

Variation
Compass variable that accounts for the difference in degrees between true north and magnetic north.

Ventilation
Air introduced into a spinning propeller from the water’s surface.

VHF
Very high frequency: a bandwidth designation commonly used by marine radios.

V-berth
A bed or berth located in the bow that has a V-shape.

V-drive
Propulsion system where the drive shaft initially runs forward into a gear box and then runs aft and down through the hull. The driveline forms a V-shape with the gear box at the pivot point.

variation
Compass variable that accounts for the difference in degrees between true north and magnetic north.

ventilation
Air introduced into a spinning propeller from the water’s surface.

VHF
Very high frequency; a bandwidth designation commonly used by marine radios.

Wake
Waves created by a moving boat.

Walkaround
A type of offshore fishing boat with a small to mid-size cabin and a perimeter deck that allows easy passage around the entire boat.

Waterline
The intersection of the hull and the surface of the water.

Waypoint
The coordinates of a specific location.

Weigh
To raise anchor.

Windlass
Rotating drum device used for hauling line or chain to raise and lower an anchor.

Working sails
Sails used in normal winds.

Yachting
To cruise or race in a large recreational boat. More commonly called Sailing for sailboats and Powerboating for motorboats.

Yaw
To deviate sharply off course (as when in a heavy sea). Yaw motion is a side to side motion due to the seaway.

Zinc anodes
Small pieces of zinc that attach to metal boat and engine components to help protect them from corrosion due to electrolysis.