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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.


To slide or drift off course.

sail plan

Arrangement of sails on a boat.


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


Full-sized, well-appointed cabin on the main deck level of a motoryacht, convertible or megayacht used for entertaining.

saltwater fishing boat

Any fishing boat used in the ocean or coastal waters that's specially equipped to handle the harsh saltwater environment.


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


The ratio of anchor rode to vertical depth.


To run before the wind in bad weather.


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


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


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

sea anchor

A canvas, cone-shaped device deployed to keep the bow headed into the wind to help safely ride out a storm. Also called a drogue.

sea cock

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


Ability to handle rough weather. Also called sea-kindly.

sedan cruiser

A type of large boat equipped with a salon and a raised helm or bridge.

selective availability

Intentional degradation of GPS signal used for position fixing by the U.S. Department of Defense for purposes of national security. With selective availability turned on, positions can be fixed to about 300 meters. With selective availability turned off, positions can be fixed to about 100 meters.


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.


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


Line used to trim a sail.


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

side console

A dash-panel unit affixed to the side of a boat. If only one, helm controls are affixed to it.


A fin or vertical projection below the hull that provides directional stability. Also, a fin-like projection at the bottom of an outboard.


A small, simple, shallow-draft boat.

skiing/wakeboarding boat

Low profile, pleasure boats with minimal deadrise specifically designed for waterskiing and/or wakeboarding. These boats are usually characterized by an inboard engine and a towing pylon. Wakeboard boats are often equipped with a tower or extremely tall pylon to fasten the tow line in a manner to aid vertical jumping and water-ballast devices to increase the weight of the boat.


A boat berth between two piers or floats. Also, the slight loss of efficient power delivery as a propeller spins in the water.


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


The deck floor.


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.


Charted water depth.


Masts, booms, gaffs and poles used in sailboat rigging.


A type of bluewater fishing boat with at least two sleeping cabins and many dedicated fish-fighting features.

spring line

A docking line attached amidships to control fore and aft movement.

stand by

An order to crewmen to be ready, be prepared.

stand on

Maintain course and speed.

standing rigging

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


The right side of the boat looking toward the bow.


A room with sleeping quarters, a cabin.

statute mile

Distance of 5,280 feet, the standard measure of distance on land and most inland waterways.


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


The most forward section of the hull.


Socket that holds the base of the mast.

stepped hull

A high-performance hull design with lateral notches, or steps, in the keel.


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.


To put an object away onboard a boat, to store.


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


Internal beams and braces that give a fiberglass 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.


To fill a boat with water.


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

swim platform

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