Boat Basics

Abaft

Toward the stern (rear) of the boat; further aft than another point.

Aft

At, near, or toward the stern (rear) of the boat.

Bearing

The compass direction of an object from the boat, or the boat's direction, expressed in degrees.

Binnacle

The housing that holds the boat's main steering compass, typically mounted on the helm pedestal.

Bollard

A heavy, short post on a dock or boat deck used to secure mooring lines.

Distress Signal

An internationally recognized signal (e.g., flares, radio call, EPIRB) used to indicate grave and imminent danger.

Draft

The vertical distance from the waterline to the lowest point of the boat's hull or keel; the minimum depth of water required to float.

Fender

A cushioning device, typically inflatable, hung over a boat's side to prevent damage when alongside a dock or another vessel.

Nautical Mile

A unit of distance used in marine navigation, equal to one minute of latitude (approximately 1.15 statute miles or 1,852 meters).

Navigation Aid

Any object or system (e.g., buoys, beacons, lighthouses, GPS) used to help a navigator determine position or plot a safe course.

Port

The left side of a boat when facing forward (toward the bow). Associated with the color red.

Starboard

The right side of a boat when facing forward (toward the bow). Associated with the color green.

Stern

The rear-most part of a boat.

Underway

A vessel that is not at anchor, tied to a dock, or aground. It may be moving or "adrift".

Yacht

A recreational boat or ship, typically used for pleasure cruising or racing, often implying a certain level of size and luxury.

Types of Lighting

Accent Lighting

Focused lighting used to highlight a specific feature, such as a work of art, an architectural detail, or a yacht's nameplate.

Ambient Lighting

The general, overall illumination that fills a space, providing comfortable visibility without focusing on any particular object.

Indirect Lighting

Lighting from a source that is hidden, with the light being bounced off a surface (like a ceiling or wall) to create a soft, diffused effect.

Marine Grade Lighting

Fixtures and components specifically designed to withstand harsh marine environments, including exposure to water, salt spray, and UV radiation.

Task Lighting

Targeted illumination for specific activities, such as reading at a chart table, cooking in the galley, or working in an engine room.

Types of Boat Lights

All-Round Lamp

A light showing an unbroken arc of light over 360 degrees of the horizon. Typically white, used for anchor lights or stern lights.

Anchor Lights

A required all-round white light displayed by a vessel at anchor to indicate its position to other vessels.

Bow Light

A navigation light at the front (bow) of the boat, typically a combination light (red/green) or separate sidelights.

Bulkhead Light

A light fixture designed to be mounted vertically on a wall or bulkhead (an interior "wall" of a boat).

Combination Light

A single fixture that combines the red (port) and green (starboard) navigation lights, typically used on the bow of smaller boats.

Deck Lights

Lights used to illuminate the open deck area of a boat for safety and activity after dark.

Dock Lights

Lights installed on a dock to improve safety and visibility for walking and for mooring a boat at night.

Emergency Light

A light, often battery-backed or portable, used to provide illumination during a power failure or other emergency.

Flood Beam

A wide beam pattern (e.g., >40°) that illuminates a large area at a shorter distance. Opposite of a spot beam.

Floodlight

A powerful light with a flood beam pattern, used to illuminate broad areas like the deck or a work area.

Green Navigation Light

The required light indicating the starboard (right) side of a vessel, visible over a 112.5-degree arc.

Landscape Lights

Used in a marine context for lighting on docks, pathways, and waterfront areas, often low-voltage and weather-resistant.

Mast Lights

General term for lights mounted on a sailboat's mast, including masthead, steaming, anchor, and spreader lights.

Masthead Lights

A white light on the mast showing a 225-degree arc, required for power-driven vessels underway. On sailboats, often refers to the anchor light at the top of the mast.

Navigation Lights

The set of required lights (sidelights, masthead light, stern light) shown by a vessel between sunset and sunrise to indicate its size, position, and direction of travel.

Port Lamp

The red navigation light indicating the port (left) side of a vessel, visible over a 112.5-degree arc.

Red Navigation Light

Same as Port Lamp. The required light indicating the port (left) side of a vessel.

Rope Light

A flexible, transparent tube containing small light bulbs or LEDs, often used as decorative or courtesy accent lighting.

Running Lights

Another term for Navigation Lights, required to be on when a vessel is underway at night or in poor visibility.

Search Lights

A powerful spotlight, often remotely controlled, used to identify objects in the water at night, such as buoys, docks, or MOB victims.

Sidelights

The red (port) and green (starboard) navigation lights, each showing a 112.5-degree arc, visible from the front and side.

Signal Light

A light used for signaling, such as a Morse code signaling lamp or a distress strobe light.

Solar Dock Lights

Self-contained lights for docks that use a solar panel to charge an internal battery, automatically turning on at dusk.

Spreader Lights

Floodlights mounted on a sailboat's mast spreaders, used to illuminate the deck and rigging.

Spot Beam

A narrow, focused beam pattern (e.g., <25°) that projects light over a long distance. Opposite of a flood beam.

Spotlight

A powerful light with a spot beam pattern, designed for long-distance illumination. See Search Light.

Starboard Lamp

The green navigation light indicating the starboard (right) side of a vessel.

Steaming Light

The white, 225-degree navigation light on the mast of a power-driven vessel, indicating it is underway.

Step Light

Small, low-profile lights used to illuminate steps and walkways for safety, also known as courtesy lights.

Stern Lights

A white navigation light at the stern (rear) of a vessel, showing an unbroken arc of 135 degrees.

Through Hull Fittings

Fittings that pass through the boat's hull below the waterline, such as for underwater lights, engine intakes, or drains.

Underwater Lights

Lights mounted on the hull below the waterline, used for aesthetic appeal, attracting fish, or checking running gear.

Warning Beacon

A flashing or strobe light used to draw attention, such as on a navigation aid, a tow, or in an emergency.

Yacht Light

A general term for any lighting fixture designed or suitable for use on a yacht, often implying high quality and style.

Marine Applications

Anchor Locker

A compartment at the bow of a boat used to store the anchor, chain, and rode. Often requires a small, durable utility light.

Boat, Sportfish & Yacht Marine Lighting Projects

Refers to the planning and installation of lighting systems for various types of recreational vessels, from smaller boats to large yachts.

Cruiser Motor Yacht

A type of motor yacht designed for comfortable, long-distance cruising, often with extensive living accommodations that require ambient, task, and accent lighting.

Marine Construction

The construction of docks, seawalls, and other waterfront structures, often requiring durable, waterproof lighting.

Megayacht

An exceptionally large and luxurious privately owned yacht, typically over 160 feet (50 meters), featuring complex, high-end lighting systems.

Motor Yachts

Yachts propelled by one or more engines, as opposed to sails, requiring a full set of navigation lights for a power-driven vessel.

Sailboat

A boat propelled primarily by wind using sails, which has different navigation light requirements than a power boat when under sail.

Yachts

(See Boat Basics) A recreational vessel, often implying a certain level of size, luxury, and complex systems, including lighting.

Dock Lights

(See Types of Boat Lights) Lighting specifically designed for installation on docks to ensure safety and visibility.

Deck

The open, horizontal walking surface of a boat, which often requires deck lights or spreader lights for illumination.

Fenders

(See Boat Basics) Protective cushions used when docking; not a lighting term, but a key boating accessory.

Bollard

(See Boat Basics) A post for securing mooring lines. Can also refer to a type of short, sturdy light fixture used for paths and docks.

SOLAS

Safety of Life at Sea. An international maritime treaty setting minimum safety standards, including for emergency lighting and signaling.

Vessels over 500 GT

Vessels with a gross tonnage over 500, which have specific, more stringent requirements for navigation and signal lights under international regulations.

Fittings & Fixtures

Cabin Light Fixtures

Interior light fixtures designed for a boat's cabin, including dome lights, bulkhead lights, and reading lights.

Color Changing Light

LED fixtures (often RGB or RGBW) that can produce a wide spectrum of colors, controlled by a switch or remote. Popular for underwater and accent lighting.

Dimmable

A light source that can have its brightness adjusted. Requires a compatible fixture, bulb, and dimmer switch.

Dimmer

A device (switch or module) that controls the voltage or signal to a light fixture to adjust its brightness level.

Exterior LED Lights

LED fixtures rated for outdoor marine use, designed to be waterproof, sealed, and resistant to corrosion and UV damage.

Flush Mounted

A fixture designed to be installed recessed into a surface (like a ceiling or bulkhead) so that its face is level with the surface.

Surface-Mounted

A fixture designed to be installed on top of a surface, with the body of the light protruding. Opposite of flush-mounted.

Contact

The electrical point within a socket or switch where a circuit is completed. Can also refer to a company's contact information.

Light Fixture Cover

The lens, globe, or decorative part of a fixture that covers the light bulb, diffusing or directing the light.

Light Fixtures

The complete lighting unit, including the housing, socket, wiring, and lens/cover. The bulb or lamp is often separate.

Interior LED Lights

LED fixtures designed for the protected environment inside a boat's cabin, often focusing on aesthetics, low power draw, and low heat.

Wireless Dimmer

A dimmer system that uses a remote control or app (RF, Wi-Fi, Bluetooth) to adjust light levels without a wired switch connection.

Lighting 101

Average Rated Life

The time (in hours) at which 50% of a large batch of tested lamps are expected to have failed.

Ballast

A device required by fluorescent and HID lamps to regulate the starting voltage and operating current.

Beam Angle

The angle of the cone of light emitted from a lamp. A narrow angle is a "spot," a wide angle is a "flood."

Brightness

The common term for luminous intensity or luminance. Officially measured in Lumens.

Candela

The unit of luminous intensity; measures the amount of light emitted in a specific direction.

Color Rendering Index (CRI)

A scale from 0 to 100 that measures a light source's ability to reveal the true colors of objects compared to natural sunlight. Higher is better.

Color Temperature

A measurement in degrees Kelvin (K) that describes the appearance of light: "warm" (yellowish, <3000K), "neutral" (~4000K), or "cool" (bluish, >5000K).

Correlated Color Temperature (CCT)

The formal term for Color Temperature, specifying the "warmth" or "coolness" of a white light source.

Definition of Color Temperature

See Color Temperature. It's based on the color a theoretical "black body radiator" would glow when heated to that temperature in Kelvin.

Direct Current (DC)

The type of electrical power provided by batteries (e.g., 12V or 24V), where current flows in only one direction. Most boats run on DC power.

Foot-Candle

A unit of illuminance (how much light hits a surface), equal to one lumen per square foot. Used primarily in the US.

Initial Lumens

The lumen output of a new lamp, before it has depreciated over time.

Kelvin Temperature Scale

The scale used to measure color temperature (e.g., 2700K is warm white, 5000K is cool white).

Light Distribution

The pattern of light cast by a fixture, which can be symmetrical, asymmetrical, spot, flood, etc.

Low Voltage Transformer

A device that "steps down" high-voltage AC power (like 120V shore power) to low-voltage AC or DC (like 12V) to power compatible lights.

Lumen

The standard unit for measuring the total amount of visible light emitted by a source. The true measure of brightness.

Lumens Output

The total amount of light (measured in lumens) produced by a bulb or fixture.

Luminous Efficacy

The efficiency of a light source, measured in lumens per watt (lm/W). Higher numbers mean more light for less power.

Lux

The metric unit of illuminance, equal to one lumen per square meter. (1 Foot-Candle ≈ 10.76 Lux).

NEMA Rating

A standard from the National Electrical Manufacturers Association that defines protection levels for enclosures against environmental hazards (dust, water, etc.).

Operating Voltage

The specific voltage (e.g., 12V DC, 120V AC) at which a device is designed to operate. Many marine lights are multi-voltage (e.g., 10-30V DC).

Photocell

A light-sensitive switch that automatically turns a light on at dusk and off at dawn.

Step Dimming

A feature where a light can be toggled between two or more preset brightness levels (e.g., High/Low) by flicking its power switch.

Through Hull Fittings

(See Types of Boat Lights) Fittings that pass through the hull, such as for underwater lights.

Toroidal Transformer

A highly efficient, donut-shaped transformer often used in high-quality low-voltage power supplies.

UL Listed

A certification from Underwriters Laboratories, indicating that a product has been tested and meets their safety standards.

Volt

The unit of electrical potential or "pressure" in a circuit (e.g., 12 Volts).

Voltage

The measure of electrical potential in Volts.

Voltage Drop

The loss of voltage in a circuit as electricity travels through a wire. A significant issue in long DC wire runs, solved by using thicker gauge wire.

Watt

The unit of electrical power consumption (Volts x Amps = Watts). With LEDs, Watts are no longer a good measure of brightness; use Lumens instead.

Wattage

The amount of power consumed by a device, measured in Watts.

LED 101

AC Voltage

Alternating Current, the type of power found in homes and from shore power pedestals (e.g., 120V or 240V). LEDs require a "driver" or converter to run on AC power.

IP Ratings

"Ingress Protection" rating. A two-digit code (e.g., IP67) that defines a fixture's level of sealing against dust (first digit) and moisture (second digit). Higher numbers mean more protection.

Gimbal

A pivoted support that allows a light (or other object) to be aimed or to remain level when its mounting is tilted.

LED

Light Emitting Diode. A highly efficient, durable, long-lasting semiconductor light source that has become the standard in marine lighting.

LED Courtesy Lights

Small, low-wattage LED lights used to safely illuminate walkways, steps, and cockpits with a soft, gentle glow. See Step Light.

Light Bulb Socket

The receptacle that a bulb's base fits into, providing electrical contact (e.g., E26 screw-in, G4 bi-pin, BA15d bayonet).

Step Dimming

(See Lighting 101) A dimming method common in LEDs that uses the existing power switch to cycle through brightness levels.

Three-Way Switch

In home wiring, a switch that controls one light from two locations. In lighting, can also refer to a switch with three positions (e.g., Red/Off/White).

Articles & Guides

Explore our guides for more in-depth information on marine lighting solutions.

• What Is a Floodlight?
• What Are Exterior LED Lights?
• Marine Light Fixtures: Essential for Safe and Stylish Boating
• Understanding Lumens: The True Measure of Light Output
• Marine Lighting Terminology Guide
• Anchor and Masthead Lights
• Green Starboard Navigation Light
• Sidelights: Port and Starboard Navigation Lights
• Harris Flotebote Boat Lights
• LED Boat Navigation Lights | USCG-Compliant Marine Lighting | DRSA