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Kayak Rudder, Skeg, Skudder or nothing?

The great debate rages on about what is the right control surface to have on a kayak. Much of it has to do with how the individual has been trained, what their first kayak was and what they have experience with. If it does what you want it to do then it isn't the wrong device! Before we explore the pros and cons of each device let us first define why such a control surface is needed and what each one is.

Why are control devices required? 

Rudders, Skegs, and skudders are required primarily to prevent a phenomenon called weathercocking. You may notice when you are out on the water in wind that your kayak will sit parallel to the waves (side to the wind) when you are not moving. The wind is effecting the kayak and the pressure from the wind works fairly equally on the front (bow) and back (stern) provided you don't have a lot of gear stowed on the top of the deck in either location. Once you start making forward movement, however, the kayakbow will pull into the wind the faster you move forward. This is due to a pressure build up on the bow of the kayak. This pressure increases with speed and has two effects:

  1. It creates a bow wake (wave) that splits off either side of the bow (each pressure point on your hull will create its own wake line) but the bow is typically the most powerful pressure point.
  2. It locks the v shape of the bow into this pressurized zone.

The Encyclopedia Britannica defines a bow wave as:

"Bow waveprogressive disturbance propagated through a fluid such as water or air as the result of displacement by the foremost point of an object moving through it at a speed greater than the speed of a wave moving across the water. Viewed from above, the crest of the bow wave of a moving ship is V-shaped; the angle of the V is determined by the relative speeds of the ship and of the propagation of waves in the water." 

This bow wave tends to keep the bow in place with a sort of resistance against that wind that pushed us sideways when we weren't moving. The stern of the kayak also has a pressure build up but it is far less intense than that of the bow, therefore the stern is more easily manipulated sideways by the wind. The resultant effect is your kayak turns upwind (into the wind) or weathercocks.

Weathercocking is fine if your destination is upwind but when it places you perpendicular to the wind then frustration levels can mount. How can we counter this effect?

There are a multitude of steps and devices to counter weather cocking:

  • Add more weight into the stern compartment pushing the hull further into the water, thus increasing the pressure in that area.
  • Place items in a drybag on the fore-deck (on top of the kayak at the front) this will catch more wind and slightly counteract the pressure that locks the bow in place in beam (broadside) winds.
  • Employ wide sweeping (sweep) strokes on the windward side of the kayak thus turning the kayak away from the wind.
  • Place more weight on the side of your glutimus maximus (your butt) that is towards the wind and keep your upper body over the center of gravity of the kayak(if the wind is coming from your right you would place more weight on your right butt cheek and lean your upper body to the left (keeping over the COG of the kayak)). This, in effect, places the kayak on its right edge. This is called "edging" or an "edging turn". It changes the shape of the kayak's wetted hull (the portion of the hull that is still displacing water). It takes a symmetrical shape in the water and makes it asymmetrical. It creates more drag on one side of the hull and forces water to flow more rapidly on one side of the hull than the other (for water that is split at the bow to meet back at the stern it must travel more rapidly on the side that is further in the water) this creates a difference in pressure from one side of the hull compared to the other which draws the hull in the direction with the lower pressure. This maneuver also unlocks the V portions of the hull and allows them to slip. Superior Paddling has an excellent diagram of the hull as viewed underwater here.
  • Deploy a Rudder. Rudders are usually placed near or at the stern and help to lock the stern in place, the rudder can also be manipulated to turn the kayak away from the wind.
  • Deploy a Skeg. A skeg is usually deployed on the underside of the hull and a few feet forward of the stern of the kayak. The skeg only acts as a fin in the water and cannot be manipulated other than up and down.
  • Deploy a Skudder, a skudder typically deploys in the same location as a skeg but has the control capability of a rudder (controlled with feet)

Rudder

The rudder itself can be deployed (dropped in the water) and retracted (brought back up into the storage yoke by pulling on one of two rotation cables.  The rotation cables are attached to the rudder's swivel wheel which is allowed to rotate thanks to a single attachment point (the Rudder Swivel Shaft).The rudder is a control device that is, typically, externally mounted on the stern or back of the kayak. The rudder has a few moving parts but typically consists of a (storage) yoke that the rudder can be folded or rotated up and forward into and some sort of rope or bungee that holds in in the yoke. The whole assembly (minus the yoke) is attached to the stern using some sort of mounting bracket (different styles depend on the manufacturer). Typically the rudder assembly is attached to the bracket and allowed to swivel thanks to a pivot shaft. The pivot shaft attaches the rudder's pivot arm onto the attachment bracket. Both the rudder and the control cables attach to the pivot arm. Pushing on the foot controls pull on the control cable which pulls the pivot arm with that foot peg, turning the attached rudder.

Rudder Pros Rudder Cons
Easy to control the Kayak (requires less edging to maintain course in weathercocking effect). Easier to turn the kayak without edging the hull. More costly to install than a skeg system or a clean hull.
Provides more space in the stern compartment of the kayak. More moving parts (lose one screw, nut or cotter pin and your rudder easily becomes useless leaving you to rely on your skill or worse leaving you to fight against a rudder you can no longer control).
Less drag in the water when stowed (clean hull) Twice the holes through bulkheads than with a skeg system (more chance of water transfer).
Provides more control when surfing (the rudder provides the steering instead of the paddle in a stern rudder orientation). The rudder can be out of the water up to 50% of the time in rougher conditions however  providing zero control during the time it is clear of the water. Rudder acts as a small sail when stowed.
Some rudders are controlled with sliding footpegs, negating the ability to use your feet, legs and thighs for stability. If you do need to push on one side of the boat you could end up turning further into trouble. (taking away much of the crucial contact between your boat and lower body)
Other rudders use toe controls which can take away from knee and thigh contact in the cockpit (taking away from your skills)
If the rudder storage device is left locked after put in the paddler must rely on another paddler to unlock it. (you will have to rely on your skills until the rudder can be unlocked)
Rendered less effective in waves (the rudder is mounted at the very edge of the kayak which is out of the water up to 25% of the time in waves). (a 75% effective rudder will leave you relying more on your skills)
Can easily be damaged by other paddlers in surf (it is exposed even when stowed (a damaged Rudder will leave you relying on your skills)
Rudders are susceptible to damage if struck while moving backwards.

 

 

Skeg

 A skeg is deployed out of the bottom of the hull of the kayak typically some some form of slider beside or behind the Cockpit. The Skeg is stored within the hull in what is called a skeg box. Most skegs have a bungee or spring that hold them up into the skeg box and a string or cable that runs up to the cockpit that is attached to a cam on the skeg. The moving parts in the operation are the skeg itself, the control cable and the actuator near the cockpit. A very simple design that works. Skegs are added to the design of a kayak to compensate for poor trim, a poorly designed kayak or newer/unskilled paddlers. A skeg will take much of the load off what a skilled paddler has to compensate for through edging. By deploying the skeg, the paddler can compensate for the stern being pushed sideways more than the bow (locked into the bow wave). The dropped skeg (typically shaped like a knife) adds resistance to the sideways motion (much like a drop skeg or keel in a sailboat).

Skeg Pros Skeg Cons
Less connection points and less moving parts. Does not provide yaw control.
Less holes through bulkheads providing less chance of water transfer. Provides for less space in the stern storage compartment
Skeg does not catch wind when stowed Skeg box provides slightly more drag than a clean hull.
Is not as effected by the stern coming out of the water in rough conditions as the skeg is located further foward. Where-as a rudder (on the very stern of the craft) comes clear of the water. Skeg boats require that the paddler have some knowledge of how to turn and control their kayak.
Foot pegs are used for bracing and no finite leg and toe control is required to steer. All muscle groups can be used to keep contact with the boat. Can be jammed by rocks and pabbles if the kayak is dragged bow first up or down the beach. Use two people, it's safer on your back!
Little chance of skeg being broken by another kayak riding up on the stern. Skegs are susceptible to damage if the kayak strikes an object sideways (not easy to do with any speed).
A stowed or deployed skeg will not impede self rescue attempts.
Skegs will typically fold into the skeg box if something is struck while paddling backwards or forwards (depending on the design).
Skegs are typically cheaper to install making a skegged boat less expensive than that of a ruddered one.

 

Skudders

Skudders are a newer concept that employs a Skeg that can be further deployed to allow for foot activated rudder type control. The system is housed in it's own stern storage compartment and control cables run up into the cockpit similar to a traditional rudder. I have not paddled a skuddered boat yet so I will reserve my opinion on them until such time I have experienced their capabilities. The skudder brings many of the pros and some of the cons of each system into one unit.

 

Skudder Pros Skudder Cons
Stored in skeg box eliminating and wind effect on the device while in storage Skeg Box creates a slight amount of drag on hull.
Allows for steering control Takes up a large amount of space in the stern compartment.

Can be used as rudder or skeg depending on severity of conditions.

Twice the holes through bulkheads compared to a single Skeg system.
Skudder would have more of a tendency to turn when striking objects sideways instead of sheering off. Can still be jammed by rocks and debris
Located under the hull which does not impede any self rescue efforts. More vulnerable to side impacts than a rudder.
Control is better than rudder in rough water due to placement on hull.

 

 

Resources

  1. http://greatoutdoorprovision.com/blog/how-to-choose-between-a-rudder-and-skeg/
  2. http://www.britannica.com/science/bow-wave
  3. http://superiorpaddling.com/kayak-weathercocking/
  4. https://www.atlantickayaktours.com/pages/expertcenter/equipment/skeg/Skeg-3.shtml
  5. http://www.venturekayaks.com/kayakAccessories.php