Experience Oregon Boating -Regulations and Safety Handbook
NAUTICAL TERM GLOSSARY
Amidships -Center of the boat with reference to its length and/or sometimes its width.
Aft -Toward the stern of a boat.
Beam -The boat's maximum width.
Bilge -Lower internal part of a boat's hull.
Boat -All watercraft, including a seaplane on the water but not in flight, used or capable of being used as a means of transportation on the water. Exemptions include boathouses, floating homes, air mattresses, beach and water toys, or single inner tubes.
Bow -The forward part of a boat.
Draft -The depth of the boat below the water line is measured vertically to the lowest part of the hull.
Fore -To or at the front of the boat.
Freeboard -Height of the boat's side measured from the waterline to the deck or gunwale.
Gunwale -The upper edge of the side of a boat or ship.
Hull -The body of a boat.
Motorboat -Any boat propelled in whole or in part by machinery, including boats temporarily equipped with detachable motors. These include gasoline and electric motors.
Port -The side of a boat to the left when facing the bow.
Personal Watercraft -Commonly known by brand names such as Jet Ski or Wave Runner, a PWC is a motorboat using a water jet pump as its primary propulsion. designed for operation by a person sitting, standing or kneeling.
Sailboat -Any boat which is under sail alone, including any sailboat equipped with a motor.
Starboard -The side of a boat to the right when facing the bow.
Stern -Back end of a boat.
Transom -Flat planking across the stern of a boat.
Underway -Boat in motion. Technically, a boat is underway when not moored, at anchor or aground.
CURRENT – An ever-present flow of the water - from timid to turbulent –where volume, channel width, and gradient (see definition below) all affect the characteristics of a river. Current is usually slower along the inside bend of a river, and faster along the outside bend. Also current is faster on the surface due to less friction than along the bottom of the channel.
GRADIENT – The steepness of the riverbed, expressed in feet/mile (an average).
RAPIDS – water flowing over an obstruction, causing turbulence. Most often formed by boulders below the surface.
HOLES – water flowing over a ledge or rock creating a void, can trap objects held in the circulating flow/hydraulics created.
HYDRAULICS – Water circulating on top of itself – evident by the churning of water below a dam or spillway. Often associated with other hazards such as holes and breaking waves.
EDDIES – Water rushing around obstacles/obstructions, circulating downstream, towards shore in a reverse current. Current flows to fill the void created by the flow of water. Sometimes violent eddies form whirlpools.
EDDYLINE – the boundary between the circular eddy and the downward current flow.
POUROVER - Think of it as a vertical eddy, water flowing over a rock, ledge or manmade horizontal structure (dam, spillway, weir) creating a "hole" below the obstruction.
DROP – Water dropping straight down – a waterfall is a classic example.
CONSTRICTED WAVE – As flowing water is constricted – by a narrowing channel - it begins to move faster. The compressed water sometimes forms waves.
WAVETRAIN – a series of non-breaking waves.
BREAKING WAVES – the top of a swell that collapses down on the upstream side of the wave (often referred to as a "stopper").
*River Glossary from Paddling.com