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Terminology


Addison Scale - An alternative system of rating rivers that considers technical difficulty, danger, and exposure as distinct elements in order to give a more meaningful description of the nature of a river. The Addison Scale was proposed by Corran Addison in the 1990s to address shortcomings in the current international river rating standard. The main disadvantage of the latter is that it summarizes every aspect of a river in a single, subjective number. Unfortunately, the Addison Scale is not in widespread use.

Aeration - The amount of turbulence in the water below a drop. Hard aeration means the water is almost calm or hardly disturbed. Soft aeration means the water is frothy with bubbles and churned up - almost like foamy soap suds. When running a drop in a kayak, the softer the aeration the deeper a kayak will sink on landing - which usually makes for a softer landing should the kayaker  land the boat flat (a.k.a boof). 

Aerial - (adjective) Used to describe any playboating move during which the kayak is entirely out of the water (e.g. aerial blunt, aerial loop, aerial backstab).
 
Angle - The difference between the facing of the boat and the oncoming current (as viewed from above). An upstream angle means the boat is aiming primarily upstream with a small offset to the current (a slight angle) or large offset to the current (wide angle). Maintaining an upstream angle is essential for a successful ferry, hence the angle of the boat to the current when ferrying is called the ferry angle. When surfing a wave or hole, boat angle is commonly described using a clock face convention with 12 o'clock being directly upstream, 11 o'clock meaning slightly to the left (when facing upstream), 1 o'clock slightly to the right (again when facing upstream), etc.
 
Attain - Moving upstream in a kayak by ferrying and eddy hopping (much like a salmon swimming upstream to spawn). Most easily and commonly done in a slalom boat. 
 
Back cut - (adjective) Squirtboating term used to describe a move initiated on the opposite (typically upstream) side against the grain of the current (e.g. back cut squirt, back cut mystery move).
 
Back deck roll - Also called a rodeo roll. The back deck roll is a method of quickly rolling upright by leaning back and sweeping the paddle around toward the stern of the boat, typically recovering in a forward lean with the paddle in a high brace position. 
 
Backstab - A blunt done backwards (i.e. with the boat starting in a back surf and ending in a front surf).

Backwash - The water behind a hole that flows back upstream toward the crease.

Bent shaft - A paddle that is bent where the hands are normally placed to provide better ergonomics for the user. Opposite of a straight shaft paddle.
 
Big water - A large volume river characterized by extremely large waves, big powerful holes, wide channels, pushy currents, squirrelly water, powerful eddies, as well as plenty of boils, pillows and whirlpools. Sometimes particular rapids that exhibit a few of these features on smaller rivers are said to have a big water feel

Blade - Normally refers to flat part of the paddle. Can also mean the entire paddle, depending on context (e.g. "Can I borrow your blade?"). 
 
Blast - Squirtboating/playboating move similar to surfing but with the stern of the boat buried deep in the foam pile of a wave or hole so that the bow doesn't pearl. A back-blast is when the bow is buried under the foam and the stern pointed upstream. 
 
Blunt

Boat - Often used interchangeably when speaking of a kayak. Can also refer to a canoe or raft. 
 
Boil - Water churning toward the surface of a river, usually created when current ricochets off the bottom. Boils are usually unstable and slightly elevated, tending to push water outward from where they first appear.

Boil line - The spot behind a hole that separates the water flowing downstream from the water flowing upstream back into the hole. The distance between the boil line and the seam or trough of the hole dictates how dangerous the hole is and how hard it is to escape the hole in the downstream direction. A big boil line - also called a wide boil line - means the water travels a relatively long distance (i.e. the length of a kayak or greater).
 
Bony - (adjective) Refers to a rapid or river that is so low that the rocks are protruding like the bones on a starving fashion model. 
 
Boof - Method of running a drop, pourover, ledge, or hole. So named for the sound the boat makes when it lands flat in the water below. Also used as a verb (e.g. "I boofed the left side of that drop and almost landed on shore!"). 

Boof stroke - The last stroke taken when attempting a boof a drop - typically planted vertically at the lip of the drop and close to the boat in order to propel the boat outward without turning it. 
 
Boogie water - Term commonly used by American kayakers to refer to continuous fast-flowing water with no defined rapids or lines. 
 
Boulder garden - Also called rock garden
 
Bow - The front of a boat.
 
Bow stall - Playboating move whereby the kayak is balanced vertically (or very nearly vertically) on its bow for as long as possible. The kayaker normally holds his paddle flat near the surface of the water to aid in balancing the boat. Kayaker normally initiate a bow stall using a double pump or paddling hard while leaning forward - the latter method is sometimes called a plow stall
 
Brace - Two varieties: low and high.
 
Braid - When a river flows through a flat gravel plain it may carve multiple channels during high water. These channels are called braids because they tend to meander and mingle with each other. 
 
Breaking wave

Broken ledge
 
Broach - (verb) The act of a boat becoming stuck sideways on the upstream side of a rock. Often used interchangeably with pin.
 
Bulkhead - 1. Sealed compartment in the bow or stern of a kayak typically used for storage and/or bouyancy. 2. Footbrace system consisting of a sliding plastic or metal plate mounted on aluminum rails.
 
C-1 - A kayak with the seat and outfitting replaced by a foam saddle and thigh straps. The paddler kneels on the saddle and uses a canoe paddle to move the boat. C-1 paddlers typically use a spraydeck with a slightly longer waist tunnel. Rolling a C-1 is harder than a standard kayak because the paddler's centre of gravity is much higher. This term is commonly used to differentiate different classes of craft in competitions (K-1, C-1, OC-1).
 
C-to-C roll - Also called a hip snap roll. The C-to-C roll is named for the shape of the paddler's body position at the start and end of the roll.

Carabiner - Also called a karabiner or simply 'biner. Screw gate. 
 
Cartwheel

Cataract - Another term for a waterfall (chiefly British). 

Catch - The part of any stroke when the paddle is first placed in the water. 

cfs - Cubic feet per second. A measurement of water flow commonly used in the US. The rest of the world typically uses cms (cubic meters per second).

Channel - The part of the river containing the main flow where the water is typically deepest and obstructions few.
 
Charc - Squirtboating term. Conglomeration of 'charging arc'. Refers to the ideal trajectory a boat should follow when entering the squeeze for the maximum squirt or mystery move potential. Has much to do with karmic goodness and wicked downtime.
 
Chine - Where the bottom of a boat meets the sides. A gentle curve (when viewed in cross-section) is a soft chine. The faster the horizontal bottom transitions to the vertical sides, the harder the chine.
 
Chop - Also called cut. A squirtboating term that refers to how much volume a boat has (medium, low, destination chop).
 
Chute -
 
Class - The technical difficulty of a rapid or section of river. Also called classificationgradelevel, or rating. There are six classes of difficulty with class I being the easiest (easy riffles) and class VI being the hardest (high risk of serious injury if not death). Further granularity is added by using +/- as a suffix. For example, a class III+ rapid is harder than a class III but not quite as hard as a class IV. A class IV- rapid is not quite as hard as a class IV. ... distinction between class of a rapid vs class of a river. .. First developed in 19??. Although ostensibly an international standard, interpretations differ. Subjective - see also Addison Scale.
 
Clean - 1. (adjective) Playboating term used to describe a move made without taking a stroke of the paddle (clean cartwheel, clean spin, clean blunt, etc). 2. (adjective) Used to describe a route with no obstacles (e.g. "That's a nice clean drop"). 3. (adjective) A move or maneuver made without making a mistake (e.g. "You had a clean line through that rapid"). 4. (verb) To perform a move or maneuver without making a mistake (e.g. "Did you see him clean that cartwheel?"). 

cms - Cubic meters per second. Measurement of flow. The US equivalent is cubic feet per second (cfs). 1 cms = 35 cfs (roughly).

Control hand
 
Controlled - (adjective) Refers to a river that is dammed.
 
Constriction - A narrowing in a river - often results in a rapid since the current must accelerate through a constriction in the river bed in order for the volume of water flowing downriver to remain constant.

Correction stroke - Any stroke that serves to turn the kayak in order to adjust or correct its course. Correction strokes provide less power than a pure forward stroke.
 
Creek - A steep, low volume river.
 
Creekboat - A specialized kayak for descending creeks typically around 8' in length. Creekboats are designed primarily to run drops and resurface quickly. Hence, they are higher in volume and longer in length compared to playboats and usually have a displacement hull. They typically have more and better rescue points and safety features like step-out bow pillars. 
 
Creeking - Also called creekboating. The sport of descending steep creeks in a kayak.
 
Curler - See wave.
 
Cut - See chop.
 
Diagonal - A typle of wave typically formed when water ricochets off an obstacle. Also called a reactionary.
 
Displacement hull - Any boat with a curved, convex bottom (when viewed in cross section). Most creekboats and all slalom have a displacement hull because it is faster than a planing hull boat with the same dimensions. Also, displacement hulls break the water better when landing flat off a drop.
 
Donkey Flip -
 
Double pump -

Down time - Squirtboating term for time spent underwater ("That seam is serving up some good down time today"). Also called sinking or roaming and generally means time intentionally spent underwater. Somewhat synonymous with mystery move but has more to do with the state of being underwater and less to do with the technique used to get there. Creekboaters/playboaters use this term to describe being pushed or held underwater involuntarily ("He got some nasty down time at the bottom of that drop").

Downstream V - See tongue
 
Draw - stroke
 
Drop - Another term for a waterfall. 

Dry exit - Unlike a wet exit which is done when a kayaker has either flipped and failed to roll or exhausted all avenues of escape, a dry exit is when a kayaker abandons his boat at the very prospect of a bad situation.  
 
Duffek - Stroke used to turn the boat without slowing it. Initially developed by Milo Duffek as a slalom technique.
 
Eddy - A pool of calm water that forms on the downstream side of an obstacle in mid-stream or behind a protrusion from shore. The most downstream part of an eddy is called the bottom. The most upstream part of an eddy is called the top
 
Eddy fence - super-depressed eddy
 
Eddy line - The line of current separating the calm water inside an eddy from the fast water outside moving downstream. Can be either weak or strong.
 
Eddy hop
 
Eddy turn -

Edge
 
Ender
 
Eskimo roll - Also called simply a roll. The roll is the basic self-rescue technique by which a kayaker rights their boat.
 
Extended paddle roll - See Pawlata roll.

Feather - 1. (noun) The degree the blades of a kayak paddle are offset. The maximum feather is 90 degrees which was prevalent prior to the early 90s. In the mid-90s, 60 and 45 degree feather was common. Less than about 15 degrees of blade offset is considered a slight feather and is common in playboating since about 2000.  No feather is a 0 degree offset. 2. (verb) Twisting the paddle so that the blade of concern - either the one in the air or the one in the water - slices through on edge.
 
Feature - A wave or hole of significance on a river.
 
Ferry - Also back ferry
 
First descent - The first time a river has ever been run by kayak. A personal first descent refers to the first time a particular kayaker runs a river, regardless of whether the river itself has been run before.
 
Flat spin - A flat spin is done on a wave. In a hole it's called simply a spin or a 360
 
Flip Turn -
 
Floatation - Also called float bags or air bags. Displaces water, thereby providing bouyancy to the boat.
 
Foot entrapment -

Freestyle - See playboating
 
Funny water

Grab loop
 
Grade - See class
 
Gradient - ... measured as a percent in Canada. In the US, feet per mile. 1% = 10m per kilometer = 53 feet per mile (fpm).  
 
Green water - Water that is fast-flowing but not turbulent. May in fact be any colour (black, brown, etc). Also refers to the water that flows underneath a hole. 
 
Hand of God - A rescue technique in which the rescuer rights an overturned boat (with the victim still in it) by reaching across the hull to grab the cockpit rim on the opposite side of the boat. The rescuer uses his weight to simultaneously push down on the near side of the boat and pull up on the opposite cockpit rim, thereby righting the boat and the victim. 
 
Hand roll -
 
Hand paddle - 1. (verb) Paddling a kayak using only one's hands for propulsion and steering. 2. (noun) Shaped plastic paddles or webbed neoprene gloves used to increase the surface area enough for hand paddling to be effective. Squirt boaters often use hand paddles to perform mystery moves because of the increased control they provide, especially when both the boat and the boater are completely underwater.
 
Happy feet/seat - Inflatable outfitting for Jackson kayaks.
 
Haystack - A large breaking wave. The white foam frothing at the top makes it look somewhat like a stack of hay - at least in shape. 
 
Headwall - A cliff toward which the river is flowing. There is usually a pillow of water where the current strikes the face of the cliff. The water will often split to the left and the right - one side being a recirculating eddy, the other downstream. 
 
Helix -
 
High brace -
 
Hip snap
 
Hip snap roll - See C-to-C roll
 
Horizon line -
 
Hole - Also called a hydraulic or reversal. How long a hole holds a boat or recirculates a swimmer determines its stickiness. holes that form at the base of a slanting ledge (called a slanting ledge hole) are typically very sticky ... smiley hole vs frowny hole. 
 
Hole hog
 
Honeycomb - heavily eroded bedrock. Common on Appalachian rivers.
 
Hydraulic - See hole

Implosion bar
 
JimiCup - The annual gathering of squirt boaters that takes place on the Ottawa River every year (typically some weekend between mid-July and mid-August). The first JimiCup was held in 1996 and attracts squirt boaters from all over the world. The event is named in honour of Jimmy Snyder, the founder of the sport.
 
JimiStick - Custom wooden paddle with peanut-shaped blades commonly used for squirt boating. JimiStyx are designed and made by Jimmy Snyder, the founder of squirt boating.
 
K-1 - Single person kayak. Usually used to differentiate different classes of craft in competitions (K-1, C-1, OC-1).
 
Keeper - Also called a stopper. A hole that big enough to either hold a boat or a swimmer. 
 
Kickflip - Aerial 360 degree rotation of the kayak along the longitudinal axis (i.e. basically a barrel roll) as the boat clears the crest of a wave.
 
Ledge
 
Line - A chosen route through a rapid. Kayakers scout a rapid in order to pick an appropriate line through it. The challenge is then to follow or 'hit' their chosen line. Most rapids have several possible lines, with some lines being more difficult than others depending on the obstacles involved, speed of the current, etc. A rapid with no safe line must be portaged.
 
Loop - A playboating move in which the kayaker essentially does a front flip in their kayak while riding a wave or hole. If the entire boat is in the air for the duration of the flip it is called an aerial loop. If done backwards, it's a back loop. In squirtboating, a loop is when the kayaker rotates the boat 360 degrees along the longitudinal axis while underwater. Squirtboat loops come in a variety of flavours (plain, light, inverted, retarded).
 
Low brace -
 
McNasty -
 
Meander

Meltdown - Squirtboating move whereby the boat and boater enter the seam of a hole and sink deep underneath it while moving downstream. Can also be done with a playboat, though playboaters frequently (and erroneously) call it a mystery move.

Mush move - Squirtboating move whereby the boat (and boater) drop completely underwater on an eddyline while moving downstream.
 
Mystery move - A classic squirtboating move - perhaps even more famous than the squirt after which the discipline is named. A mystery move is initiated by performing a bow squirt and stern squirt in quick succession in order to sink the boat on the seam of an eddy line. Better control and down time can be achieved by using hand paddles to effect a mystery move.
 
OC-1 - A solo open whitewater canoe. This term is commonly used to differentiate different classes of craft in competitions (K-1, C-1, OC-1).
 
Offset - The amount (in degrees) that the blades of a paddle are offset when looking down the length of a paddle. Also called feather. Paddle offset ranges between 0 and 90 degrees. 
 
Off side - Any move done on your weaker or less favoured side. Initially, eskimo rolls and most playboating moves (blunt, cartwheel, squirt, etc) are easier to do on your on side as opposed to your off side. Most kayakers strive to be equally proficient at both sides.

Oil can - A warped, concave depression in the bottom of a boat caused by excessive heat, improper storage, tying the boat too tightly to roof racks, or extensive use. A boat will usually oil can at one or more weak points in the hull, often under the seat or where the bow or stern pillars fail to prevent the boat from flexing. A boat with an oil canned hull is worth less for resale.

Old school - (adjective) Used to describe equipment or playboating moves that predate the era of the modern playboat (basically anything before 1997). Enders, pirouettes, shudder rudders, and paddle twirls are considered old school as are 90 degree offset paddles, plastic helmets (especially Pro-tec), and high volume Bouy-o-boy style PFDs.
 
One-arm bandit - Squirtboating move in which the paddler plants the paddle in the water but instead of performing a forward stroke they pull the boat around and over the paddle and paddler. The same move but without planting the paddle at all is called a no-arm bandit. This move was perfected (and possibly invented) by American squirtboat world champion Deb O'Keefe.
 
Open boat - A whitewater canoe (either solo or tandem). Someone who paddles an open boat is called an open-boater.

Otter Slide -  Entering the water by sliding down/off a rock face. Similar to a seal launch but involving less air time.

Outfitting
 
Paddle wax

Pan am -
 
Park and play - Also called destination playboating. Instead of running the river, the kayaker remains at and plays on/in a single feature all day.
 
Pawlata roll - Also called an extended paddle roll. The Pawlata roll involves shifting the hands on the paddle so one hand grips the end of a blade while the other holds the shaft near that same blade. This makes it easier to roll upright because of the extreme leverage afforded. However, the time and risk involved in changing grip and the danger inherent in holding the blade makes this roll useful only for instructional purposes.  
 
Pearl - (verb) When the bow of the boat is forced underwater by the oncoming current while ferrying or surfing. Using a knee to aggressively lift the upstream edge of the boat will usually cause the bow to resurface (or prevent the boat from pearling in the first place).
 
Peel out - Another term for eddy turn, but refers exclusively to leaving the eddy.

Pencil - (verb) A method of running a waterfall by landing with the kayak vertical. The kayak tends to go deep on impact, requiring a deep pool at the base of the drop. Most often used on high drops or low volume drops with little or no aeration at the bottom. Pencilling a shallow drop is a bad idea and is generally the result of a messed up boof

PFD - Acronym for personal flotation device.Synonymous with life jacket as far as kayakers are concerned, although the government distinguishes the two. 
 
Phonix monkey - . Supposedly named after a South Park episode.
 
Pillar - The foam support in the bow and/or stern of the kayak that adds rigidity to the hull in order to prevent the boat from collapsing when pinned or broached on rocks. Some creekboats have step-out bow pillars with notches or steps to make it easier to escape the boat in the event of a vertical pin. 
 
Pillow - A layer of water that forms a cushion between an obstacle in the river (typically a boulder or rock face) and the oncoming current. Kayakers can sometimes avoid hitting an obstacle by riding or surfing their boat on the pillow of water in front.
 
Pin -
 
Pirouette - Using the paddle to spin the boat around its longitudinal axis when performing an ender. The ideal is to do a full 360 (or more) spin and land upright. 
 
Piton - To strike a rock with the front of the kayak, typically by penciling into the water below a drop. 
 
Pivot turn - Slalom term.

Planing hull -
 
Play -
 
Playboat - Any boat less than about 6'5" in length with a flat planing hull.

Playboating - Also called freestyle kayaking
 
Pool-and-drop - Term used to describe a kind of river. Pool-and-drop rivers have large, calm pools of water between each rapid. Generally safer than rivers that are more continuous in nature because the former afford safer places to effect rescue and recovery of swimmers and gear. 
 
Portage - Carry boat around a rapid. In Canada it's pronounced to rhyme with 'massage' whereas the American pronunciation rhymes with 'marriage'.
 
Pothole - A circular hole eroded into bedrock by smaller rocks being swirled in the current. Can be up to several feet in diameter and depth. Potholes pose a foot entrapment hazard when underwater and also are prone to catching and holding logs in rapids.

Power face - The concave part of the paddle blade that pulls the water  when performing a forward stroke. The non-power face is the convex back part of the blade.

Pourover -
 
Probe - The lead kayaker or first person to run a difficult rapid as an example for the rest of the group. 

Prusik loop - Also called simply a prusik

Put in - The start of a section of river. 

Rating - See class.
 
Reactionary - A kind of wave formed when water ricochets off an obstacle.
 
Recirculation -

Riffles
 
River left - The left bank of a river when facing downstream (and it remains the river left bank when facing upstream as well). Directions are always given with respect to river left and river right because they are less confusing than simply 'left' or 'right' which can change based on orientation.
 
River right - The right bank of a river when facing downstream (and it remains the river right bank when facing upstream).

River signals - A common set of paddle, whistle, and hand signals used by kayakers, canoeists, and raft guides to communicate on the river. 

Rock 360
 
Rock splat - see 'splat'.

Rocket move - Squirtboating and playboating move where a stern squirt done at the base of a wave while moving downstream causes the boat to rocket off the crest. 
 
Rodeo - A freestyle kayak competition in which competitors perform as many tricks as possible in 60 seconds.
 
Rooster tail - Plume of water caused by an obstacle in the river abruptly redirecting the flow.
 
Rudder -
 
Run-off -

Run-out - The bottom of a rapid. 
 
Scout
 
Screw up - Squirtboating/playboating move performed when the boat goes past vertical and falls over (typically during a squirt but could be any move). Basically, the kayaker sets up and performs a roll while the boat is falling instead of waiting for it to hit the water. 

Sculling

Seal launch - Entering the water by dropping off of a rock. A seal launch typically involves at least some air time. Because the paddler must enter and launch their boat on their own and afford little to no control, seal launches are famous for causing injury - usually from over rotation, pitoning, paddle to the face on landing, or landing flat in non-aerated water.  

Seam - seam of wave, seam of hole, seam of current. 
 
Shoal - Shallow rocky area in a rapid or river.

Shudder rudder - Squirtboating and old school playboating move where the boater leans back and rudders directly behind him while surfing.
 
Shuttle
 
Shuttle bunny - Person (typically female) who drives kayakers to and from the river, put in, and/or take out but who does not themself paddle.

Side-surf
 
Sieve - A sieve is formed by a narrow constriction between two obstacles - usually rocks. Sieves are dangerous because water will flow between (or under) the obstacles but a boat and/or boater risks becoming lodged by the force of the water, making exit and rescue difficult.
 
Siphon - Similar to a sieve except that the opening through which the water is forced is completely underwater. An extremely dangerous river obstacle to be avoided at all costs.
 
Slalom - Racing a kayak down a rapid through a series of gates (poles strung in pairs from wires across the river). The paddler must pass downstream through the green gates and upstream through the red ones. Hitting or missing a gate incurs a time penalty. Slalom is an Olympic sport and many slalom courses are artificial (i.e. man-made). Slalom training is ideal for developing strength, endurance, and efficient paddling technique. Most top playboaters come from a slalom background.

Slalom boat - Style of kayak used for slalom racing. Slalom racing requires that boats be fast and the sport is governed by strict rules concerning boat dimensions. Hence, slalom boats are made of some kind of composite materials (fibreglass, kevlar, or carbon fibre) and are long and skinny. 
 
Space godzilla -
 
Spear - To hit (or be hit) in the body by the front of a kayak. Typically the result of an unintentional collision. 
 
Spillway
 
Splat - Squirtboating/playboating move whereby the paddler performs a squirt in front of a rock or rock face, then setting the bow against the rock and letting the boat ride the pillow in front or slide along the pillow beside. Can also be used as a verb (e.g. "I'm gonna splat that big rock in midstream!"). Splatting a rock as you paddle by - almost like a cartwheel against the rock face - is sometimes called a rock swipe. Since a splat can be done with either the bow or the stern of the boat, it is sometimes differentiated as a bow splat or stern splat
 
Splitwheel -
 
Sprayskirt - Also called a spraydeck. Neoprene deck and tunnel worn by the paddler that fits over the cockpit of the kayak to keep water out.
 
Spud boat -
 
Squeeze - Squirtboating term refering to the point in the eddy line where the upstream current slams into the downstream current. Squirts and mystery moves are best initiated in the squeeze.
 
Squirrelly - (adj.) Refers to unstable and unpredictable water, especially in an eddy or along an eddy line.
 
Squirt - Squirboating/playboating move in which the paddler forces the stern of their kayak into the oncoming current, typically when crossing an eddy line. The current piles up on the stern which pushes the bow of the boat vertical. Can also be used as verb (e.g. "I'm gonna squirt that eddy line!").
 
Squirtboat - A slow, extremely low volume, custom made, composite kayak used primarily for performing elegant surface moves and/or roaming around underwater. Because they are intentionally made as small as possible, squirt boats tend to be uncomfortable. However, because they are custom made they can be of any colour, cut, or design you want. Squirtboats traditionally incorporate metal flake into the gel coat to make the boat shimmer in the sunlight. Why? Because chicks dig glitter...

Squirtboating - The sport of experiencing the third dimension of a river in an extremely low volume kayak.

SRT - Acronym for Swiftwater Rescue Technician. A certification no kayaker should be without. The acronym is often used interchangeably as the certification (e.g. "Do you have your SRT?").
 
Standing wave -
 
Stern - back of boat
 
Stern stall -

Stomp - Mid-air method of forcing a kayak more vertical when running a waterfall.
 
Stopper
 
Strainer - tree protruding from the water
 
Sub out - 'subarine' out. Called a meltdown when done intentionally in squirboating.

Super-depressed eddy
 
Surf - Can also be done backwards (i.e. with the stern pointing upstream) in which case it's called a back surf.
 
Surfer's Ear - Called exostosis in the medical profession. Bony growths in the inner ear caused by repeated exposure to cold water. Affects kayakers too.  
 
Sweep - 1. A wide arcing stroke from the bow to the stern used to turn a kayak. A reverse sweep is the same but in reverse and using the non-power face of the paddle. 2. A kayaker designated to bring up the rear of a group and ensure there are no stragglers. 
 
Sweep roll -
 
Sweeper - tree hanging over the water
 
Swimmer - A kayaker that has exited their boat (in the river).

Swimmer's ear - Called otitis externa in the medical profession. Painful inflammation of the ear canal. Affects kayakers too.

Take out

Throw rope - Also called a throw bag.
 
Tongue - Also called a downstream V. A tongue of green water. 
 
Tricky whu -

Trim
 
Uncontrolled - A river with no upstream dams or weirs that restrict flow. Also called free-flowing.
 
Undercut - Rock that has been eroded such that water passes partially or completely underneath. The absence of a pillow of water in front of a rock or rock face is often an indication that it is undercut. Undercuts are extremely dangerous to swimmers because they can become stuck underneath (or caught on wood that has been stuck underneath).

Up button - Squirtboating term that means to intentionally force your boat to re-surface, typically during a prolonged mystery move ("I was running out of air so I hit the up button"). Generally, the easiest way to hit the up button is to lean back and your boat should,hopefully, rise to the surface.
 
Washout - Squirtboating move.
 
Washed out - At high water, many rapids formed by mid-stream obstructions are drowned, washed out, or quite simply underwater. 
 
Wave - . Green vs breaking (curler). surfer's left/right or wave left/right.
 
Wave train - A series of large standing waves, typically located at the bottom of a rapid. 
 
Wavewheel - Squirtboating/playboating move where the kayaker forces the boat on edge and performs a cartwheel at the peak of a wave. 
 
Weir - Low-head dam.

Wet exit
 
Whirlpool
 
Whirlygig - Squirtboating move
 
Windowshade - When side-surfing in a hole and the current catches the upstream edge of a kayak, the boat and paddler will be violently flipped to the upstream side. Typically the kayaker can roll up on the downstream side but if they use too much edge they may be flipped upstream again, and again, and again - much like a windowshade being rolled up.  

Wood - Generic term for any kind of wooden hazard. log or tree floating, logjam, strainer, sweeper. Unfortunately, there is no established river signal for wood so most paddlers simply yell "Wood!" to alert the rest of the group the instant they spot the hazard. 

Worked - Act of being tossed about helplessly and unintentionally out of control in a powerful hole or at the base of a waterfall ("I ran the drop but got worked at the bottom."). 
 
Worlds - Freestyle Kayaking World Championship competition hosted in a different country every two years (2009, 2011, 2013, etc). The competition that takes place the yearbetween is called the pre-Worlds and takes place at the same location as the Worlds but one year before (i.e. basically a dry run). The summer 2007 issue of Rapid Magazine documents the history of this competition. 
 
Wrap - When a boat pins on an obstacle and is folded around it by the force of the water. The crease that forms where a boat is wrapped weakens the integrity of the hull, making wrapped boats less safe for future use and worth less for resale.

Yard sale - When multiple kayakers come out of their boats in the same place at the same time. This results in gear floating everywhere and makes rescue tiresome and time-consuming. Too many yard sales on a trip turns it into a shit show

Z drag - A system of slings, pulleys, and prusik loops that uses mechanical advantage to winch a pinned boat off of an obstacle. The most basic Z drag provides a 3 to 1 mechanical advantage, though additional hardware can easily increase this to 5 or 6 to 1. Carabiners can be substituted for pulleys at the cost of increased friction.