Kayak Pedal Drives – Hype vs. Reality
This article examines pedal drive propulsion for common (mono hull, sit-in and SOT) kayaks from several technical angles, which are: Ergonomics – How does it feel to operate a pedal driven kayak, and what are the potential physiological drawbacks in this type of propulsion. Mechanics -How efficient are pedal drives’ pedaling systems. Hydrodynamics -How efficient are pedal drives’ propellers, and how effective is pedaling kayaks compared to paddling them. Real World Performance – How effective are pedal driven kayaks in applications such as fishing trips, stand up fishing, fishing in moving water, fishing in shallow water, launching, beaching, etc.
We’ve shown the W kayak paddled both with double-blade (‘kayak’) paddles and in the canoeing (single blade) style, rowed, and poled, as well as sailed, and motorized with electric motors, outboard gas engines, and an air-jet motor. Since we’re interested in showing our kayaks propelled by different means, we also tested pedal drives.
This article does not compare the performance of sit-in and SOT kayaks, whether paddled or pedaled, with the performance of W kayaks.
- Launching and Beaching
- Shallow Water
- Moving Water
- Reverse Mode
- Stand Up Kayak Fishing
Introduction – About Pedal Drives for Kayak Propulsion
Pedal propulsion for small watercraft has been in use since the 19th century, and it’s still commonly found in small recreational boats, often in a combination of rotating pedals with paddle wheel type propellers. Other types of pedal driven propulsion systems for small craft include rotating propellers, hydraulic pumps, sideways moving flaps, add-on systems, and more. Interestingly, the world speed record for a human powered watercraft is held by a catamaran equipped with a rotational air propeller.
Currently, there are three kayak manufacturers offering pedal driven kayaks. Two of them offer kayaks featuring a combination of rotational pedals with a rotational propeller, and one manufacturer offers a drive featuring push pedals combined with flaps moving from side to side, in a back and forth motion. The latter will be simply called ‘flaps’ in this article.
All three kayak pedal drives are fixed, which means they provide propulsion without steering, and therefore, the kayak operator is required to track and turn using a hand activated rudder.
All three pedal drive systems feature pedals located in proximity to each other, along the kayak’s center line, and at a higher point than the kayak seat. In order to activate the pedals in all three, kayakers have to relocate their feet away from the low footrests situated on both sides of the hull.
Part 1. Pedaling Kayaks’ Ergonomics –
How Does It Feel To Operate a Pedal Driven Kayak?
The first and main argument in favor of pedaling kayaks instead of paddling them, is that our legs are far more powerful than our arms are, and therefore it makes more sense to use our legs for difficult tasks such as propulsion, rather than using our arms.
While being generally true, this argument is not necessarily applicable to the propulsion of kayaks. This is because although our legs have the biggest and most powerful muscles in our body, and are best fit for hard, long lasting efforts, using them for propelling any vehicle must be done under certain conditions, which are dictated by our own built, and ability to endure certain types of effort –
Limbs that have bigger muscles are comparable to engines with bigger cylinders – They can burn more fuel, and thus generate more power. The legs of a kayaker pedaling their pedal driven kayak generate considerable force, and this force is transmitted from their body to their kayak through three points:
1. The kayaker’s two feet, which the kayaker’s legs push forward, against the pedals, and –
2. The kayaker’s lumbar spine and lower back, that the legs push backward, compressing them against the backrest of the kayak’s seat, so as to provide support for the legs’ pushing effort in the opposite direction.
The force each leg applies on a pedal when pushing it is equal to the force the leg applies on the kayaker’s lower back, and this creates a big ergonomic problem.
Pedaling in the L position (recumbent) is essentially different from pedaling in the upright position (e.g. biking). The difference being that in biking, our legs push against our own body weight, and its that weight which supports the legs’ downward push against the pedals, and allows them to move. Recumbent bicycles have been known to exist since the 19th century, but upright (riding) bicycles outnumber them at a ratio of more than a thousand to one, simply because recumbent bikes are harder to use, meaning that they present serious ergonomic issues that upright bikes don’t.
Pedaling common kayaks is done in the L position, which is similar to the recumbent position. The L position is kayaks is known to cause a variety of back problems starting from premature fatigue, acute pain known as yak-back, and other problems including one known as yak-ass, circulation problems in the legs. In extreme cases it may even lead to a painful, chronic condition called sciatica, caused by the vertebrae in our spine compressing the sciatic nerve, which is the largest group of nerves in our body.
These problems are accentuated by the fact that the driver of a pedal propelled kayak cannot switch positions. This means that the above mentioned symptoms tend to occur shortly after the kayaker starts pedaling, and their severity can increase rapidly.
Kayak Pedaling vs. Kayak Paddling – What the Difference Feels Like
So far, this article discussed the issues of power generating, how this power is used to propel the kayak forward, and what the pedaling kayaker feels in their back and legs. But operating a kayak does not involve just propulsion – it is more complex and demanding than that:
Stability and Control
First of all, a kayak being such a small and inherently unstable craft demands that the person who operates it take care of balancing and controlling it actively, using their own body for this purpose.
It is important to remember that while pedal drives may be used solely for propulsion , paddles are useful for propelling as well as balancing the kayak. This is particularly difficult for kayak pedal drivers, since they are required to move their feet away from the footrests, located low and on the kayak’s sides, and place their feet on the pedals, located higher, and on the kayak’s center line. This repositioning of one’s feet severely reduces their ability to control and balance the kayak, and for this reason pedal kayak drivers are often seen holding the sides of the kayaks while pedaling them – By holding the kayak’s sides with their hands in such a way, they try to compensate for the loss in balancing capability as a result of their repositioning their feet to a less stable position, and no longer being able to use them for either balancing or control.
Tracking and Turning – Directional Control
Since the operators of pedal driven kayaks feel less stable than paddlers do, pedal driven kayaks must be made wider than average kayaks. Aside from the fact that such excessive width slows down the kayak, it also makes it track very poorly, thus presenting yet another challenge to its operators, especially in adverse conditions such as wind and current that are often present in real life.
Here again, pedal drives provide propulsion without contributing to the kayaker’s ability to steer their kayak. In contrast, a paddle provides its user with effective means for controlling both tracking and turning, while propelling the kayak at the same time.
A person operating a pedal driven kayak is compelled to steer by operating a hand activated rudder, a fact which presents a number of problems:
To begin with, rudders aren’t easy to use, and demand constant attention, and while paddled kayaks can be steered with a foot activated rudder, pedal driven kayaks must be steered with hand activated rudders.
Second, rudders slow down the kayak by 10% in average, making it harder to maintain good speed.
Third, when going in shallow water, rudders are prone to get stuck in underwater obstacles and scrape the bottom, as well as harvest seaweed that’s difficult to get rid of before the kayak is beached.
Push Pedals vs. Rotational Pedals – What Difference Does it Make for the User?
Pushing a pedal forward with your foot across a small distance is a very limited movement, far different in its range of motion from a full step you take when you walk. Performing such a limited movement repeatedly, and while using your legs’ full power is bound to result in unwanted physiological side effects. Such effects include early local fatigue, foot and leg cramps, as well as stress injuries in the muscles, tendons, and joints of your legs and feet that are directly involved in this extremely restricted, powerful and repetitive motion.
In comparison, rotating a pedal is a more complex, and therefore fuller movement of your legs and foot, which is more comparable to making a step while walking, and therefore it is less stressful for your legs and feet, and has fewer unwanted side effects than activating a push pedal does.
Part 2. The Mechanics of Kayak Pedal Drives –
Comparing the Efficiency of Rotating Pedals and Push Pedals
Any motor, or drive should be as efficient as possible, meaning that it should lose as little energy as possible. This is particularly important in human propelled systems, because the human body is capable of generating so little power in a sustained manner. In fact, the number commonly used for the sustained power output of an average individual is 0.25 horsepower (HP) – far less than the power of a small motorized lawnmower, or the electric garbage disposer in your home.
So How do Kayak Push Pedal Drives Compare to Rotating Pedal Drives?
When you turn the pedals of a rotational drive, you generate uninterrupted motion, which means that all kinetic energy you’ve generated (momentum) is preserved, and not lost. Simply put, your pedals are an efficient means for transmitting all the power that your body generates to the propeller, at a minimal loss in energy terms.
In contrast, when you push the pedal of a kayak’s pedal drive, and stop at the end of the push motion, you lose all the kinetic energy that you’ve created while accelerating the pedal. This means that the next time you push a pedal, you’d have to accelerate, and pay a high price in energy terms, since accelerating is difficult. Such total loss of all kinetic energy is repeated each time you activate a push pedal. One can hardly imagine a less efficient system, or one that wastes more of the driver’s energy, without achieving anything more than a rotational pedal system does.
Part 3. Hydrodynamic Performance of Kayak Rotating Propellers vs. Flapping Propellers
A boat’s propeller is the drive’s part that comes in contact with the water, and transmits the power created on board to this element, in order to make the boat advance through it. For example, the blade is the paddle’s propeller.
Most motorboats are equipped with rotational propellers whose axis of rotation is parallel to the boat’s direction of movement, although few still feature paddle wheel style propellers whose axis of rotation is perpendicular the boat’s direction of movement.
The motion of a rotating propeller in continuous, and therefore such propeller wastes little kinetic energy.
In contrast, stopping and accelerating a propeller makes it lose momentum, and demand that extra power be spent on accelerating it. Such loss is precisely what occurs when the flaps of the kayak flap-type drive move from side to side in the water, and stop each time to change direction and go back. It’s hard to imagine a less efficient propeller, especially since abrupt change of direction (back and forth) generates vortices in the water that further reduce the propeller’s efficiency.
In sum, a kayak pedal drive combining push pedals with side-to-side moving flaps is the least ergonomic, least mechanically efficient, and least efficient solution from a hydrodynamic standpoint.
Simply put, activating such drive for human powered propulsion is tiresome and wasteful, and does not seem to serve well the purpose of recreational boating and fishing. It seems however, that it such exercise may be effective for burning extra calories in a shorter time, for those who are willing to bear the discomfort associated with it.
Pedal driven kayaks use the power produced by the driver’s legs, and their manufacturers claim that this fact makes them faster. But does it really?
Let’s examine the facts:
1. Pedal driven kayaks are less stable than comparable, paddled kayaks. Because of this fact, pedal driven kayaks must be made wider than comparable paddled kayaks, and this extra width makes them slower, as it exponentially increases the residual resistance (Rr) of the water they move through, as a function of their speed.
2. Pedal driven kayaks must feature a rudder, unlike paddled kayaks that can be steered without such accessory, to some extent. A rudder increases frictional resistance of the water, and decrease the kayak’s speed by 1o% in average compared to the speed of the same kayak without a rudder.
3. Pedal driven kayak’s additional width also makes them heavier, and considering the fact that they the drive itself adds extra weight, as well as the rudder, no wonder that pedal driven kayaks form the world’s heaviest class of kayaks. Such heavy kayaks are slower, and harder to propel than other kayaks are.
3. Hull speed is a number related to the hull’s length. The longer the hull, the higher its hull speed number. Practically speaking, when a kayak attains its hull speed, it becomes very difficult to further increase its speed, unless a disproportional amount of energy is used for this purpose, and the big majority of people simply don’t have such stamina. Being essentially recreational kayaks, pedal driven kayaks are not as long as sea kayaks and racing kayaks are, and do not possess the characteristics of catamarans’ ultra-thin hulls. In other words, they are slow.
4. Length to Beam (L/B) – The Form of a Kayak as a Function of the Application it’s Designed to Serve: All pedal driven kayaks are ‘chubby’, meaning that the ratio of their length to width (Length to Beam, or L/B) is too low to be considered as efficient in speed terms. Such kayaks are also heavier than other, comparable kayaks that propelled with paddles.
In sum, pedal driven kayaks are by definition recreational kayaks, used for recreational touring and fishing, and never for professional racing. Therefore, attempting to drive such kayak at high speed, especially if it’s equipped with inefficient push pedals and flaps, is an exercise in futility for the greater majority of people. Such exercise is likely to end shortly after it began, with the average kayaker experiencing cramped legs, back pain, and a sore butt.
Part 4. Real World Performance
Recreational and fishing kayaks, including pedal driven ones, are operated outdoors, in the real world, which is very demanding in many aspects, especially if you’re a regular user, in average physical shape, or below it, as the great majority of people are.
Getting to The Water, and Back From it – Transportation
The begin with, pedal driven kayaks are particularly heavy – heavier than any type of kayak. This is because they must be made wider than comparable, paddled kayaks, in order to compensate the driver for the loss of stability resulting from their feet being in a different position. On top of this, all pedal driven kayaks feature a rudder as well as the pedal drive itself, and those add to the kayak’s excessive weight. Being so heavy, some of these kayaks’ require their owners give up the idea of car topping them, and use a trailer instead, which altogether defies the purpose of using a kayak, which is essentially cartop boat.
As far as carrying goes, that is transporting the kayak from the car to the water, and later back from the water to the car, being heavier than other kayaks makes pedal driven kayaks more difficult to carry, and in some case s they may even turn out to be impossible to carry.
Kayak Mobility, or Lack Thereof
Whether you paddle for fun, or to get to places where you want to fish, your kayak should enable you to launch where you want, go where you want, and beach where you want. The kayak’s capacity of doing so is measured in Mobility terms.
Launching and Beaching Your Kayak
As far as launching and beaching are concerned, the performance of pedal driven kayaks is similar to that of other monohull kayaks, be they sit-in or sit-on-top (SOT) kayaks. This is due the the ability to removed the drive from its mount before launching, or beaching, but it also implies that the kayaker must carry a secondary means of propulsion on board, that is a paddle, which is says something about the overall reliability of pedal drives as means of propulsion.
Kayaking and Fishing in Shallow Water and Vegetation-Rich Water
A kayak should enable you to go where you want, as much as possible. In this sense, pedal driven kayaks are considerably inferior to paddled kayaks, because they’re not suitable for going in shallow water, or water where vegetation is to be found, or in moving water.
Shallow water and water with lots of aquatic vegetation are among anglers’ favorite fishing areas. Since both rotational and flap propellers tend to harvest seaweed and bump into underwater objects, or the bottom, kayak anglers who own pedal driven kayaks need to remove the drive when reaching shallow or vegetation-rich waters, and they have to keep progressing using the paddle they must keep on board, or walking in the water. During that time, they keep the pedal drive on board – yet another large size object in a small, already cluttered and rather dysfunctional space.
Kayaking and Kayak Fishing in Moving Water
Currently, pedal driven kayaks feature two types of hull – a traditional SOT hull, which is essentially a paddle board, and a hybrid kayak and canoe hull, which is essentially a canoe hull, less most of the freeboard offered by regular canoe hulls. The latter is perfectly useless in moving water, since its lack of minimal freeboard makes it easily fill with water, even from eddies. Contrarily to what some people believe, the SOT hull isn’t self bailing – only the SOT deck is. The SOT features scupper holes that drain water down from its deck, which gets frequently covered with water, as such kayaks feature too little freeboard as well. Although SOT kayaks can go in moving water, pedal driven ones are more restricted in doing so than paddled ones, because recumbent pedaling is basically a less stable means of propulsion than paddling. This is the result of the repositioned feet from the footrests to the pedals, and thus denying them any role in balancing and control.
Needless to add that the combination of moving water and shallow water, such as found in streams, presents an impossibility to pedal driven kayaks.
In sum, pedal driven kayaks are less fit than paddled kayaks are for going in aquatic environments that both recreational paddlers and anglers favor. In other words they offer a considerably reduced Mobility.
Fishability – The Kayak’s Performance As a Fishing Craft
Proponents of pedal driven kayaks advance the the notion of ‘Hands Free Kayaking’ as their principal argument in favor of using those kayaks for fishing. Basically, the idea is that an angler pedaling their pedal driven kayak can fish at the same time, and manufacturers of such kayaks have been able to produce demo movies showing how it’s supposed to be done. Remember – we’re talking here about fishing, and not trolling, which can be done from any kayak.
The problem with this notion of ‘Hands Free Kayaking’ while fishing is that it’s a falsehood, because of the following reasons that pertain to pedaling kayaks, as well as to fishing.
1. In normal circumstances, there is no way you can pedal a kayak and go where you want, unless you use a hand operated rudder for steering and tracking. This leaves you with only one hand free, and because pedaling a kayak feels inherently unstable, you’re likely to need this second hand to grab the kayak deck on the side of your seat, or at least lean on it.
2. Fishing with a rod requires the use of both hands.
That is of course unless you’re trolling, in which case you can hook fish without using your hands, just by by sticking your fishing poles in your kayak’s rod holders, and going forward either in a paddle driven or pedal driven kayak.
A paddle is a highly versatile tool, enabling its user to go forward, steer, and balance their kayak, as well as going backward. Steering and going backward are essential to being able to position and control the kayak when you fish a spot, or an area. Rotational pedal drives offer steering through the use of a hand activated rudder, and they have a reverse mode. As for flap pedal drives, they altogether lack a reverse mode.
Stand Up Kayak Fishing
Pedaling a kayak is less stable than paddling it, which is why pedal driven kayaks need to be wider and stabler than comparable kayaks. That extra width, which results in extra weight and less speed, is used by pedal driven kayaks manufacturers to suggest that their products are fit to fish standing on. But they’re not – assuming you manage to get up from your seat, and stand on top of a board, or a kayak, or a SOT kayak, which is essentially a paddle board. You’re good for as long as there’s absolutely nothing that can destabilize you, but assuming you’re out there, in the real world, there will always be something that will make you loose your balance – guaranteed. It could be a fish jumping in the water behind you that makes you turn your head, or a wake sent your way from a distant motorboat, a sudden gust of wind, or even a fish pulling on your line – anything can, and will eventually cause you to lose your balance, simply because you’re standing on a small, unstable platform. When you stand on top of a SOT, hybrid, or sit-in kayak, there is no Plan B available or such cases, and you’ll go swimming, as will your fishing gear.
This article reveals the discrepancies between the image of pedal driven kayaks as easy to use, fast, offering hands free kayaking and stand up fishing, and the reality of their being uncomfortable, clumsy, heavy, hard to operate, and rather dysfunctional as far as Mobility is concerned.
Interestingly, the newer type of drive featuring push pedals and sideways moving flaps turns out to be less ergonomic, as well as less efficient in mechanical and hydrodynamic terms than the older drive featuring rotational pedals and a rotational propeller.
This article focuses on the difference between two modes of propulsion: paddle and pedal, in common kayaks featuring similar, conventional hull type, that is mono hull kayaks. In order to keep things simple and clear, we chose to focus solely on the difference in propulsion modes for kayaks, and avoided introducing additional fundamental differences such as hull type (mono hull vs. twin hull).
It is important for the reader to remember that when compared with mono hull sit-in and SOT kayaks, Wavewalk’s patented twin hull W kayaks offer superior performance in paddling as well as in fishing, in all these dimensions and parameters:
Stability, Ergonomics, Biomechanics, Comfort, Protection From the Elements, Storage Space, Ease of Launching, Ease of Beaching, Mobility, Ease of Steering, Ease of Tracking, Ease of Paddling in strong Wind, Versatility, Casting, Fishability, Stand Up Paddling, Stand Up Fishing, Speed, and more. The readers are welcome to learn more about these advantages offered by W kayaks, through technical articles, demo movies, and customer reviews on the Wavewalk Kayaks website.
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