Quarter
The sides of a boat aft of amidships

Quartering Sea
Sea coming on a boat's quarter.

Rigging
The general term for all the lines of a vessel.

Rode
The anchor line and/or chain.

Rope
In general, cordage as it is purchased at the store. When it comes aboard a vessel and is put to use it becomes line.

Rudder
A vertical plate or board for steering a boat.

Run
To allow a line to feed freely.

Running Lights
Lights required to be shown on boats underway between sundown and sunup.

Satellite Navigation
A form of position finding using radio transmissions from satellites with sophisticated on-board automatic equipment.

Schooner
First seen among 19th-century ships. It is multimasted and furls triangular sails. The foremost mast is always shorter than the others. 

Scope
Technically, the ratio of length of anchor rode in use to the vertical distance from the bow of the vessel to the bottom of the water. Usually six to seven to one for calm weather and more scope in storm conditions.

Screw
A boat's propeller.

Scuppers
Drain holes on deck, in the toe rail, or in bulwarks or (with drain pipes) in the deck itself.

Sea Cock
A through hull valve, a shut off on a plumbing or drain pipe between the vessel's interior and the sea.

Seamanship 
All the arts and skills of boat handling, ranging from maintenance and repairs to piloting, sail handling, marlinespike work, and rigging.

Sea Room
A safe distance from the shore or other hazards.  

Sea Anchor
Any device used to reduce a boat's drift before the wind.  

Seaworthy
A boat or a boat's gear able to meet the usual sea conditions.  

Secure
To make fast.

Set
Direction toward which the current is flowing.

Ship
A larger vessel usually thought of as being used for ocean travel. A vessel able to carry a "boat" on board.

SHEAR PIN
A safety device, used to fasten a propeller to its shaft; it breaks when the propeller hits a solid object, thus preventing further damage.
SHEET- Adjusts a sail's angle to the wind. 

Sheet Bend
A knot used to join two ropes. Functionally different from a square knot in that it can be used between lines of different diameters.

Shoal
An offshore hazard to navigation at a depth of 16 fathoms (30 meters or 96 feet) or less, composed of unconsolidated material. 

Shrouds
Run from the top of the mast to the port (left) and starboard (right) side of the hull to give sideways support.

Sloop
A single-masted vessel with working sails (main and jib) set fore and aft.

Slack
Not fastened; loose. Also, to loosen.

Sole
Cabin or saloon floor. Timber extensions on the bottom of the rudder. Also the molded fiberglass deck of a cockpit.

Sounding
A measurement of the depth of water.

Spring Line
A pivot line used in docking, undocking, or to prevent the boat from moving forward or astern while made fast to a dock.

Splice
To permanently join two ropes by tucking their strands alternately over and under each other.

Spring Line
A pivot line used in docking, undocking, or to prevent the boat from moving forward or astern while made fast to a dock.

Squall
A sudden, violent wind often accompanied by rain.

Square Knot
A knot used to join two lines of similar size. Also called a reef knot.

Square-Rigger
Large ships dating back to the 17th century typically with three masts carrying rectangular sails mounted on horizontal beems called yards.  

Standing Part
That part of a line which is made fast.The main part of a line as distinguished from the bight and the end.

Stand-On Vessel
That vessel which has right-of-way during a meeting, crossing, or overtaking situation. 

Starboard
The right side of a boat when looking forward.  

Stem
The forward most part of the bow.

Stern
The after part of the boat.

Stern Line
A docking line leading from the stern.

Stow
To put an item in its proper place.

Swamp
To fill with water, but not settle to the bottom.