Surfski 101 - A Glossary of terms

In my profession, documentation is God, and based on the recent inquiry and Robs excellent start, it gave me the idea to create the Glossary of common surfski terms which may help beginners understand the sport specific lingo many of us take for granted.

I copied the first section the Rob typed up (thanks Rob!) and added on from there. Obviously I am no authority on the sport, but everything is described to the best of my ability. Many of these topics could fill a book by themselves, so its just a basic starting point for most things.

If anyone would like to correct or add anything, feel free! This is certainly not comprehensive yet. 

Boat terminology -
Port - Left
Starboard - Right
PFD - Personal Flotation Device  / Life jacket / life vest. Although the true definition of a 'life jacket' is much larger than is practical for paddling, here in the US, PFD in common language means a Type III flotation device. There is a related ISO spec as well. I think its around 50 newtons buoyancy or 17lbs? 
PLB - Personal Locator Beacon like a SPOT brand tracker. Old ones only had an Emergency button that called rescue services. New ones allow someone to monitor your location, send an "im ok" text, and call for emergency help. They are a great backup plan when in large conditions or deep wilderness. 
VHF Radio - a marine band radio that can be used to call to other boats nearby, the harbor, coast guard, or anyone listening to VHF bands. Most are waterproof, and nice ones have geo-location capability and can function similar to a PLB
Float Plan - a plan of where you intend to launch, paddle to, and return, how long you expect to be gone, who you're going with, what you're wearing, etc. At minimum, a friend or loved one should always know these things. You can also call it in to your local harbor or coast guard. In extreme conditions, this will prevent someone calling in an unintended rescue on you, or alternately if you're in trouble, someone knows approximately where to look.
Cockpit: the part of the boat that you sit in, including both the area where your bum goes and where your feet rest.
Bucket, Seat - the part of the cockpit that your bum sits in.
Footwell: the forward part of the cockpit where your feet go.
Footplate: the flat board that your feet rest on.
Foot pedals/rudder pedals: the pedals that the tops of your feet press on to activate the rudder.
Rudder lines - the steel cable or Spectra (rope) that connects the foot pedals to the rudder. Steel cables are stiffer (do not stretch) and provide a more precise feeling, but are generally harder to adjust 
Rudder Tubes - The rudder line travels from the foot plate to the rudder box inside a tube. This tube is inside the hull.
Rudder box - the compartment on the top of the boat that houses the top of the rudder. This is where the rudder lines connect to a spreader plate which connects to the rudder shaft. It is typically covered by a shield to prevent stu
Nose/bow: the front-most part of the ski
Tail/stern: the rear-most part of the ski
Rails: the top edges of the cockpit.
Rocker: the amount of bow to stern curve in the bottom of the ski.  A ski that has a lot of rocker looks like a banana; a ski that has little rocker looks much flatter.  Skis with plenty of rocker catch waves more easily but are slower on flat water (as a general rule).
Wave deflector: A small shield taped to the front deck in front of the cockpit that deflects water coming over the nose of the ski and helps prevent the cockpit from being flooded.
Leash: made from rope or coiled plastic with a padded, Velcro fastening on end that typically goes around a paddlers ankle and a rope loop on the other end that generally goes through an anchor point on the bottom of the cockpit.  Prevents the paddler from losing the ski when they fall off in windy conditions. Anytime there is even light wind, it is strongly recommended to use a leash since a boat can very easily be blown away faster than you can swim.
Stringer - a piece of foam that provides strength and rigidity to boats. It typically is a vertical piece in the nose and tail. Some boats have horizontal pieces as well. Stringers are critical to boat strength in designs that use them. (newer monocoque designs typically do not have a stringer, as the hull itself is designed to take all loads. This type of design is lighter, stiffer, and more expensive than tringer type designs. An example of a monocoque hull is the Epic GT layup, All new Nelo layups, all modern OC1/OC2 layups. Basically all the premium, ultralight carbon layups available from most brands. Many of these layups use Pre-Preg carbon, which is the lightest and stiffest type)
Beam - the maximum width of the boat
Bailer / Scupper / Venturi - the drain in the bottom of the cockpit that operates on the Venturi pressure differential principle
Bullet - imagine a rain drop, cut in half the long way. These are made of carbon, and about 2-3" long and the width of the venturi opening. You put bullets immediately behind a permanent venturi with a small gap, like maybe 1/4" or 6mm. They aid in bailing out the cockpit because it lowers the minimum speed required to bail (create suction) and makes the replacement water flow around the venturi smoother
Glass - short for Fiberglass. A woven fabric made of spun glass. Its cheap, easy to work with, and repair (because it can be sanded). Its also one of the heaviest and weakest composite fabrics, which is why its typically on cheaper and heavier layups. 
Kevlar - is technically DuPont corporation's name for Aramid fiber, but no one calls it aramid, everyone calls it Kevlar regardless of who made the cloth. (like Band-Aid is to disposable bandages). Kevlar has excellent tensile strength but relatively poor compression strength. For this reason, it is only used in some areas or specific layers of a layup. It is lighter and stronger than Glass. It is a horrible, awful, terrible material to repair because it cannot be sanded. If you try to sand it, it just fuzzes up and will never become smooth. For this reason, it is rarely used as an outer layer.
Carbon - Carbon fiber. The lightest, stiffest, and most expensive cloth available for composite layups. It can be readily sanded and is easy to repair just like Glass. One downside is that carbon's yield and failure strength are nearly equal. This means that when carbon fails, it catastrophically fails in an instant. Little or no warning is given before it breaks. Compare that to Steel. Steel has a relatively large range between yield strength (the point at which it permanently deforms) and failure strength (the point where it breaks). it will bend quite a bit before it catastrophically fails, which gives you some warning of its impending failure and some time to react. Carbon on the other hand is more or less binary, in that its ok, or its broken. There is no such thing as 'half broken' with carbon. This is well known to those who have ever broken a paddle
Pre-Preg - refers to a cloth that is Pre-Impregnated with the ideal amount of epoxy resin. No additional resin is added, thus you have the absolute lightest layup possible with current technology. It must be stored in a refrigerator or freezer until its ready to be used since the resin is temperature cured. Once the cloth is laid up in the mold, it is baked in an autoclave (large oven) to cure the resin. All the super fancy carbon fiber stuff is Pre-Preg now days. Epic's GT layup, most ultralight OC1's, and most brand's premium layup is now Pre-Preg
Uni or Unidirectional cloth - Uni carbon fiber only have fibers running parallel to one axis. This provides maximum strength in one direction, but poor strength in other directions. Typical cloth is woven at 90°, which provides good strength from all directions. Weaving cloth is a science and you can have weaves with 4 or more directions of thread. Depending on the direction of the load, a different weave or Uni will provide optimum strength and minimum weight. '
Spread Tow Fabric - A special, ultra stiff fabric weave type made under the trade name TexTreme. Most common carbon fiber has a small weave that is like 1/8" (3mm) square. This is not ideal because every over/under intersection creates a small space for unneeded resin to pool up. With spread tow fabric, the weave size is very large, like 3/4" or 20mm. This is what makes the distinctive checkerboard pattern of the fabric. Because there are less over/under intersections, less resin pools are available to be filled, and thus the final product is stiffer and lighter than standard weave. Most super-premium composites are spread tow, such as F1 cars and ZRE ultralight canoe paddle blades. I read that a spread tow layup has 20,000 less weave intersections (per square yard maybe?). 
Excess resin actually makes a layup weaker and heavier, so minimizing excess resin is key to high performance layups.  
Vinylester resin - the cheapest resin that can be used to create a composite layup. Its highly toxic and the least strong from what I understand
Polyester resin - A middle-grade resin. It is stronger and slightly more expensive than vinylester. Also slightly less toxic from what I understand. 
Epoxy resin - The strongest, most inert, and most expensive resin available for composite layups. Used in mose medium and high performance layups.
Vacuum bagging / Vac'd layup - A method of composite molding where you place the cloth in a mold, apply resin, then cover it in an air-tight bag. You connect a vacuum pump to the bag and it sucks the air out, which compresses the fabric and resin. This leads excess resin to come out of the layup, reducing weight and increasing strength. All good quality layups are now vacuum bagged.
Vacuum infusion - a derivative of vacuum bagging - instead of applying resin by hand, the cloth is laid in the mold and covered with the vac bag. No resin is applied yet. Vacuum is applied. Then, the valve to the resin pot is opened, and resin is sucked into the cloth. This continues until  resin comes out the other side of the mold. It has similar properties to a vacuum bagged layup due to its similar principle of compressing the cloth and removing excess resin.
Stability - The tendency of a boat to resist roll (side to side change in center of gravity). Stability comes from additional water displacement. Typically, boats with a large difference between static waterline width and maximum beam have more stability, because there is more beam in reserve that can displace water which translates to more righting moment. 
Primary Stability - describes how stable or settled a boat feels initially, sitting very close to centered (think ±15° from center as a general estimation). Primary stability determines how twitchy a boat feels as you sit in flat water. boats with a round hull or v hull have low primary stability. Boats with a flat hull (or flat spot on the hull) have higher primary stability. In general, wider boats have more stability in general, both primary and secondary, although hull shape affects this. (You could have a very wide, round hull with almost no stability regardless of width, but almost no one makes round bottom boats because its a poor design for a ski hull).
Secondary or Final stability - how much rolling resistance is gained as the boat is leaned far over (more than 15° from center up to the point of capsize).
Final point of stability - The point at which you will capsize unless a righting moment is applied (for example, by a brace or strong rudder input)
Stability considerations - it may be counter intuitive, but a boat with high primary stability is better on flatter water and low primary stability is better for messy water. Imagine you're paddling directly across the waves (coming from your side) - flat bottomed boat wants to follow the angle of the wave face up as the wave approaches, then down as it passes by. A more rounded bottom is less affected by the angle of the water underneath it because the cross section of the wetted area remains more constant. For this reason, a boat with low primary high secondary is ideal for big conditions, because it is not very affected by rough or unpredictable water shape, but also has a large reserve of secondary stability to keep you upright when you're slightly off center. High secondary also provides you more time to throw down a brace if needed, reducing the chances that you swim. 
-A perfectly round bottom I believe is theoretically the fastest hull shape, however it has 0 stability (primary or secondary. More or less an Olympic K1) so almost all boats have some out-of-round or flat spot on the hull to make them manageable. 
-Boats with the same beam can still have significantly different stability profiles, depending on how round the hull is, if it has a flat spot, how much it flares between static waterline and max beam, and how much rocker it has. 
 
Paddle Stroke terms -
Catch - part 1 of 4 in the paddle stroke. This involves the motion of placing the blade in the water at the proper position and orientation. It ends as soon as the power phase begins
Power Phase or Pull - part 2 of 4. The power generating portion of the stroke. It begins once the blade is fully planted in the water. It ends around your hip or slightly before. It is important to not allow the power phase to go too far back, as this can be a waste of energy and detrimental to speed.
Exit - Part 3 of 4 - the motion of pulling the blade out of the water at the end of the power phase
Recovery - Part 4 of 4 - the time when both blades are out of the water and you are setting up for the Catch on the opposite side
Dive under - the tendency for some blade designs to twist unexpectedly and pull the blade inward towards the hull, which often leads to a capsize
Brace - using the paddle to provide stability. There are 3 types -
Skim brace - when the boat is surfing down a wave, it is common to stick the paddle far out to one side and let it gently skim over the top of the water. Typically I will let the paddle skim behind me at 30-60°. This way, when you are ready to take the next stroke on the opposite side, your other blade is already in position allowing you to begin the next stroke at a moments notice. Also, the skimming blade is better positioned hydrodynamically should you need to turn the skim brace into a hard brace. When at medium to high speed, this provides a lot of stability and can  compensate for unexpected loss of stability. This is particularly useful when going downwind or riding any wave. Standard operating procedure is to skim brace when riding a wave. When done properly, very little or no speed loss should be observed, except when a strong brace is needed. In that case you push the paddle into the water more to provide additional stability as needed.
Slap Brace / Stalling brace / Hard brace - (at least that's what I call it, not sure if there is a better term) - a hard, violent brace that greatly reduces your speed. It is typically only used to prevent an uncontrolled capsize. Although a strong slap brace will slow you down a lot, it’s still better than capsizing. It is similar to a skim brace, except you violently push the blade down into the water.
Stroke Brace - Each stroke can be used to make small corrections to your position and center of mass. One great thing about wing paddles is that they provide lateral resistance which can be used as a 3rd point of stability.
When properly executed, stroke braces do not cost any speed at all. 90+% of the energy still goes into forward motion, but maybe you push, pull, or rotate the blade slightly such that you stabilize yourself without breaking cadence. This
is the most preferred method of bracing, since you're still propelling yourself forward. This is particularly useful in tippy boats and rough conditions. In really rough conditions, every stroke is also a brace in the sense that it is providing lateral stability.
 
Rudder types
Flat water - a small, short rudder that is used when waves are very small, typically less than 4" or 100mm. They are as small as possible to minimize drag
Weedless - a rudder with a backwards rake angle typically higher than 25 or 30°. The steeper angle sheds weeds and is very useful in waters with Eurasian milfoil or kelp mats.
Shark fin - exactly as it sounds, shaped like a shark's dorsal fin. This rudder is best used in races with a beach finish. Its design is not easily damaged by dragging the boat up the beach haphazardly. However, the smallest part of the rudder is at the tip, so in large or steep waves it is not very effective
Elliptical - a rudder in the shape of 1/2 of an ellipse.This is the typical 'large' rudder available from most OEM's. although its surface area is larger, it still has a small tip which may be an issue in steep or short waves
Surf - a generic term for a large rudder which is best used in large conditions.They are typically in the 7-10" range
Airfoil - Debatably the best shape for a rudder according to hydrodynamics. It has a similar cross section to an airplane's wing, except both sides are convex and a mirror image of each other. The end is cut off bluntly which provides full surface area down to the tip (where you need it most in steep conditions). They can be any length. The most common source currently is DK Rudders from Don Kiesling, This email address is being protected from spambots. You need JavaScript enabled to view it.. (Side note - I highly recommend his products)
High Chord - a modifier to an airfoil rudder. A high chord means it’s longer in the length direction (the long axis of the boat) as opposed to the depth. This adds more surface area to the rudder and thus makes it more powerful 
Stall - term in fluid dynamics when the flow around a surface is no longer laminar (smooth). Stalled flow is turbulent and much of the turning power is lost when an airfoil is stalled. A thicker leading edge on a rudder reduces its
tendency to stall because the sharpness of the angle/radius that replacement water must make is larger. Thus, higher angles of attack are possible before stall.

Wind and Waves
- Runner/Run: A wave on the open ocean that can be surfed.  The Aussies call them runners, South Africans call them runs.
- Downwinder/downwind: a paddle where you're going with the wind,surfing the waves.  Aussies call them downwinders, Saffas call them downwinds!
-Side Saddle - a method of remounting the boat from the water from the side. You flop yourself onto the bucket perpendicular to the boat, then kick, twist, and plop your butt in the bucket. This is the most common and probably first choice method to remount.
- Cowboy or Scramble - a method of remounting where you lay on the back deck behind the bucket, slide forward until your butt is over the bucket, then sit up. This method may be better in very rough conditions because your
arms and legs provide stability throughout the process.  
Link / Linking waves: When going in the same direction of the waves or at a shallow angle to them, linking waves is when you choose a line that allows you to jump over the wave in front of you and begin surfing a new wave. Linking
waves is critical to peak downwind speed. It is an art that is learned over time. Not all conditions allow linking. Typically shorter period waves are easier to link (as in approximately less than 8 second interval). Typically to link a set of wave you travel at an angle to the wave, not straight down it or else you will run into the wave directly in front of you.
Swamp - a flooded cockpit. This is not desirable because a cockpit full of water adds significant mass to the boat, and makes it harder to accelerate onto a wave
Interval or Period - a reference to the amount of time between the peaks of waves. (i.e. how long does it take for 2 waves to pass the same point in space). Theoretical open water wave speed is 1.5*Interval(though in reality interaction with the ocean floor changes this, but that’s too complex to estimate) It is very important to understand the relationship between wave height and interval because it determines how steep a wave is and how easy it is to surf. A 3m 15 second wave is unsurfable because it is moving so fast and has a shallow face due to its long period. On the
other hand, a 1m 5 second wave is perfect surfing because they are spaced closely, moving at a reasonable speed, and steep enough that you don’t have to work too hard. In general, 2-5 second interval is considered short and steep wind waves. Depending on height, they may be too steep. 6-9 seconds are low-medium interval wind waves perfect for surfing. 10-15 second is long period ocean swell generated over long distances. 16+ second swell is very
long period swell with a ton of energy when they approach shore. The longer the period, the more the wave will build when it approaches shore, since there is more water in the wave to stack up. Consider that a 0.3m wave at 20 second interval can easily stack up to over 1.5m when it breaks.
Wind wave or wind swell - short to medium period waves generated by local wind (wind within a few miles of you). I would say their period could be defined as less than 8 seconds and go as low as 2 or 3 seconds. Wind waves will dissipate quickly if the wind dies or changes direction. Wind waves are steeper than ground swell and are more useful for paddle-up surfing due to their steepness and short period. Wind waves are often used to 'boost' you on to fast moving and shallow ground swell that would be impossible to catch if it were not for the wind wave boost. 
Ground Swell - Medium to long period ocean swell. To me, this means an interval of greater than 10 seconds, and usually closer to 14+. Ground swell is generated by wind over long distances (100's or 1000's of miles). Ground swell will travel very long distances without losing much energy. It will also wrap around points and into bays without losing significant size. Ground swell is what surfers like, because the long swell stacks up slowly and predictably at breaks, which allow for good surfing. If there are no wind waves to boost you on to it, long period swell, no matter how big or good it looks will just tease you as they go underneath you. Because they are very fast moving and shallow waves, typically ground swell will not allow paddle-up surfing. At best you get a repeating pattern of boost-stall-flat water-repeat as the wave overtakes and boosts you, you stall and paddle up the back side, then paddle the flat water between waves. 
Primary swell - on the ocean or other large body of water, it is common to have multiple swell directions. Typically there is one direction which is dominant, and maybe 1-3 smaller directions. Generally, primary swell is the most useful, because it is generated nearby and is bigger and steeper than secondary swell.
Secondary Swell - the other, smaller directions of swell. Alternately, it can be in the same direction as the Primary, but maybe its a different size and interval.That is possible when wind is in the same direction as groundswell. 
Reflected waves - When a wave crashes against a steep, solid surface such as a rocky cliff or sea wall, the wave piles up, then reverses direction, effectively sending the wave back in the direction of the sea. The exact direction of the reflected wave depends on the vector at which it hits the wall. The larger the wave, the more prevalent the reflected wave will be. 
Reflected waves can be both useful and detrimental depending on the situation. If you are paddling out into open water, you can use reflected waves to boost you out, just like surfing waves in. In this case, they do not have nearly as much energy or steepness as the incoming waves, however there is a noticeable push you can exploit from reflected waves. On the other hand, if you're paddling parallel or at a shallow angle to the wall, now you have waves attacking you from both your left and right side (plus front and/or back depending on how many swell directions there are). In this case, your stability will be put to the test and a situation like this is what we often call a washing machine, because waves are coming from every direction. 
Confused seas / Haystacks / Washing machine - At minimum this typically refers to at least 2 swell directions, but in my experience the worst is when you have 3 or more swell directions spanning at least 90° and possibly up to 270° or more, with some of the swell large enough that it reflects. Similar to the washing machine described above, when you have Primary swell, secondary swell, tertiary swell, wind waves, and reflected waves all coming from different directions, the sea looks more like moguls on a ski hill than parallel waves. "haystacks" form where the peaks of waves intersect. All the waves will be traveling at different speeds and have different sizes from different directions, so you cannot reliably predict when or where a peak or hole may form. This describes some of the most challenging conditions to paddle in. The boat may 'fall out from under you' at any moment as peaks and valleys combine unpredictably. In these conditions, a low primary stability high secondary stability boat is ideal, and the use of continuous stroke braces is often necessary to constantly adjust your center of gravity. Assuming you can stay upright and apply power effectively, you can still surf in conditions like this. But if you are power limited due to instability or excessive bracing, you should be in a more stable boat for the conditions. Basically all the pros agree, if you are power limited due to instability, you will be slower than if you were in a more stable (wider/slower) boat but able to apply 100% power. 
Beam waves - waves hitting you from either side (left or right). Assuming 0° is straight ahead, beam waves would be at 90 and 270° ± some deviation
Quartering waves - waves hitting you at an angle, from the front or back. Assuming 0° is straight ahead, quartering waves would be at 45° ,135°, 225° or 315° ± some deviation

Crumbling waves / Whitecaps - Open water waves that are so steep, they collapse on themselves. Whitecaps often indicate good downwind conditions because they are formed by local wind and will dissipate quickly if the wind dies. 
Outlier / Sneaker / Standout - Wave height is distributed along a bell curve. Most waves will be within a certain, small-ish range,however there are outliers that are both much smaller and much larger. Small outliers will be a lull in the waves. Large outliers may be 2-3x the median wave height. Outliers are very important to watch out for when surfing near or just outside shore break. If you surf in a medium size wave and a large outlier is behind it, it will break further out, and you may be trapped inside the break zone, which is where most boat damage and injuries occur. For this reason, it is a good idea to bail off a wave with some buffer in case a bigger wave is behind it. If you wait until the very last moment, the larger wave will likely break on you before you can paddle out far enough, which is bad, mkay.
Critical - the point at which a wave begins to curl over itself and break, typically this occurs at shore, a reef, or sandbar.
Set - in reference to a set of waves, typically only formed on large bodies of water like oceans, seas, or the great lakes. Waves travel in sets typically between 6 and 12 waves long. a set will have a similar size, either smaller, average, or larger than median. Typically a large set will be followed by a smaller set, then some median sets, then another large set. Local conditions determine how consistent wave size is. Depending on where you are, there may be a small or large difference in wave size between sets.
Drafting or Wash Riding - most useful in flat water racing, but can be used upwind and crosswind as well. Similar to a race car or bicycle, the lead boat experiences more resistance than the boats immediately behind and to the side of it. Also, the lead boat generates a wave that following boats can use to their advantage. For this reason, in races it is very common for packs to form and for following boats to 'ride the wash' or 'draft' the boat in front. Be sure not to hit the boat you're drafting. Also, best etiquette says you should take turns 'pulling' the pack, assuming you're not going for Gold. You typically cannot wash ride downwind or down-wave. Even if you could, its more useful to look for a good wave.
Hole - A hole in surfskiing hopefully is not referencing a leak in your boat. Typically a 'hole' is the part of the wave you want to paddle for. Holes are areas the provide excellent surfing on the down-slope side of a wave. The goal is to get on a set of wave, then traverse left or right to find a 'hole' which will allow you to 'link' a 'set' together. Holes are most prevalent when you have waves coming from at least 2 directions.  On the ocean it is common for multiple swells to be offset by 10-45°. When the different directions combine, very obvious peaks and holes form, similar to moguls on a ski hill. Your goal is to traverse from hole to hole without being caught behind a peak.
Climbing - the uphill side of a wave. This is where you don't want to be. On longer period swell, the uphill side of a wave may be quite large, and you are literally paddling up hill for a while. This costs you speed and energy. You want to avoid paddling up hill as much as possible by effectively linking sets. 
  
 

Wowsers you guys sure went to town thank you so very much! That is absolutely exactly what I was looking for so many thanks to Rob and Mcimes for that comprehensive doc.  

Good idea, very educational.
Since I'm dealing with rudder system repairs, I just learned about the term "line feeder" and of course there's rudder tube, rudder line/rudder cable.
In the past, I also didn't know the proper term for padeyes and a lot of other deck hardware
maybe also "beam waves", "reflected waves" and "confused seas"
perhaps "port" and "starboard" would be worth adding.
"PFD", "VHF radio" , "PLB" and "Float Plan" might belong on the list too

Rocker: the amount of bow to stern curve in the bottom of the ski.  A ski that has a lot of rocker looks like a banana; a ski that has little rocker looks much flatter.  Skis with plenty of rocker catch waves more easily but are slower on flat water (as a general rule).

I think this needs slight amendment.