CHOOSING AN OPTIMAL PADDLE

CHOOSING AN OPTIMAL PADDLE FOR BRACING AND ROLLING
AS WELL AS THE FORWARD STROKE
by Ken Rasmussen

    A well prepared touring paddler uses a variety of strokes. There are strokes for propulsion, for bracing, for turning, and for rolling. We usually choose our paddle solely for its forward stroke characteristics—often based upon what feels good on flat water during the first few minutes of a test. Many paddlers aren’t aware of the compromises that affect the performance of a paddle when one considers all of the strokes one might use. I’ve been aware of my forward stroke preference for some time. Recently, I decided to gather more information about paddle performance, especially as regards rolling and bracing. I once tried a wooden paddle that amazed me with its appropriateness for the sculling brace and for rolling, so I began my research with the notion that buoyant blades might be a good idea for a rolling paddle. I naively presumed that all wooden blades were probably good for rolling, and that bigger would be better. The first wooden paddle I tested proved that I was wrong. It tended to climb too steeply when swept through the water edgewise, consequently losing laminar flow, and stalling. Wide blades have that tendency.


Blade Design Characteristics
    The parameters influencing blade performance are the cross sectional shape, the longitudinal curvature, and the outline shape. Performance characteristics affected by these include: The efficiency of the paddle, which is its resistance to slipping backwards through the water during a stroke. The tendency to flutter or not during a stroke. The response of the blade to a sculling motion, such as climbing, diving, twisting, stalling, etc. The tendency to draw air into the water behind the paddle which causes cavitation—not desirable. The ability to create lift when one is using an angled forward stroke.
    There are a variety of blade styles: Flat, dihedral, spoon, and wing are the common face shapes. * Each blade has two faces, the power face, which is the aft face; and the back, which is the forward face. The longitudinal curvature might be straight, curving or bent. The blade shape can be symmetrical or asymmetrical.
    Wing paddles are designed to resist slipping backwards, and also develop some lift when pulled sideways during the stroke. The sculling performance of wing paddles is usually not likeable. Spoon shaped paddle blades, like wing blades, are intended for high efficiency. Dihedral blades tend to flutter less than other shapes. Flat blades are moderate in most respects. The power face of the paddle is the most important as regards forward stroke performance. When the paddle is slid sideways through the water, or used with an angled stroke, the cross sectional shape is important, because the paddle acts like an airplane wing.
    Width is extremely important. Efficiency generally improves with greater width. Edgewise sweeping and sculling are usually adversely affected by excessive width. The blade will exhibit an inclination to climb too steeply and stall.
    Bent paddles are common in single blade canoe paddles, but rare in double bladed paddles. These change the moment of greatest propulsion in the stroke, delaying it until the blade has traveled further aft. Longitudinal curvature with the concavity aft is intended to improve the efficiency of the paddle blade. Longitudinally straight blades are more forgiving in their characteristics.
    Most paddles have an asymmetrical shape. The rationale is that if the blade is only partly immersed and is entering the water at an angle when power is applied, the lower half of the blade will have more surface exposed to pressure than the upper half of the blade, causing the paddle to want to twist in the hand. An asymmetrical design will tend to reduce this twisting characteristic. Realistically speaking, one wants to have the entire blade submerged before power is applied, otherwise cavitation will result. Hence this feature only has a benefit to a person who paddles incorrectly. However it does no harm, and may look “cool”.
    The choice of blade style is influenced by purpose. A racer would prefer a blade that wouldn’t draw backwards through the water (high efficiency) and would be less concerned with bracing and rolling characteristics or energy conservation. A tourist would be interested in minimizing strain and having good bracing, rolling and stroke versatility. Few of us understand blade design well enough to know what a paddle will act like until we try it. Different models of wing paddles, for example, act very differently from one another. I can’t tell whether a paddle will tend to draw air into the water until I try it. Sculling performance is hugely variable, and very important for bracing and sweep rolls. The subtle interactions of design features have more to do with the success of a paddle than the nominal style of the blade. Testing is the most comprehensive way to understand how a paddle works. The skill of the paddler has a lot to do with its performance. Any paddle will work better if used more skillfully; consequently some paddles may be badly behaved for some and well behaved for others.

Blades for Rolling and Sculling

    I sought out paddles for testing that had buoyant blades, usually wood, but also composite paddles (fiberglass and carbon fiber) with low-density cores. The wooden paddles proved to be the most buoyant, probably because makers of composite paddles are waging a battle to achieve ever lower weights. Low weight is closely identified with high quality in the marketplace. It would be possible to make very buoyant composite paddles, but they would have more material in the blades, causing them to weigh more than other composite paddles, which would tend to decrease their commercial success.
    There are two types of rolls: Sweep rolls and brace rolls. Brace rolls don’t use the sweeping portion of the roll for support, depending instead upon the downward pressure of the blade against the water. Brace rolls are characterized by a convulsive hip snap. A brace roll is most easily done with a paddle with a large floating blade and a long shaft. The configuration of the blade is almost irrelevant. The sweep roll uses support from the paddle during the sweep to roll the kayak. The hip snap is diffused throughout the sweeping and rolling process. Most rolls are a synthesis of sweep and brace rolls, containing elements of each.
    When I compared the paddle blades that worked best for edgewise sweeping and sculling I realized that these were long and moderately narrow. I wasn’t able to find enough design diversity to draw firm conclusions about the optimum cross sectional shape, but it was apparent that wooden paddles outperformed composite paddles due to the greater thickness of the blades. ** Since paddle makers aren’t generally designing for sculling the most optimal cross sectional designs for this are not being commercially produced. Optimized designs might have some relationship to airplane wing design, but more symmetrical since they would be sweeping both forward and aft. When loosely held, the most successful wooden paddles tended to find the correct climbing angle for sweeping and sculling. These also slid effortlessly through the water, making a fast sweep easy to do. Those characteristics, combined with the tendency to float, made a solid platform for sweep rolls and sculling braces. Some of the paddles that I thought might do well for sculling and sweeping didn’t, due to differences in cross sectional shape. Others sculled nearly effortlessly, and had a good sweep for rolling, but didn’t give as much support for the final portion of the hip snap because the blades were small. These differences proved the importance of actual testing in order to evaluate paddles.
    While doing research on the Internet I found a website*** which describes paddles for sculling a coracle, a boat that resembles an upside down umbrella, possessing little directional stability, which is paddled from the bow. Since the coracle depends entirely upon effective sculling for propulsion, coracle paddlers know exactly what sort of paddle to use. Their observations corresponded closely with mine, except that they have researched cross sectional shapes, and prefer a blade that is symmetrical and moderately convex on both sides. Symmetrical convex cross sectional designs aren’t available in kayak paddles, but we could expect such a blade to be less efficient in its resistance to drawing backwards through the water, resistance to flutter should be good, and sculling should be excellent. In addition such a blade style should develop lift when used with a forward stroke that incorporates some side movement, thus improving its efficiency.
    Some readers must be fairly bouncing in their seats by this time, saying, "I know, I know, I know!" We are describing something a lot like a Greenland paddle. I’m not qualified to discuss Greenland paddles since I don’t use one, but it must be evident to any of us who have observed a good Greenland style paddler that these blades are very effective for sculling braces and sweep rolls. In contests between racers using wing paddles versus other racers using Greenland paddles the results were close. Apparently the Greenland designs can hold their own for both rolling and propulsion. It takes some extra effort to learn to use them effectively.

Why Inefficiency Might be Effective
    All of us would expect high efficiency, that is the resistance of the blade to slipping backwards, to be a universally positive characteristic. That isn’t actually true. I once went paddling with a fellow who had designed his own paddle. It had a bent shaft and a blade the size of a sandwich. Several of us were paddling upstream into a stiff wind. At first the fellow with the ridiculous paddle couldn’t keep up. Then, as we fatigued and he didn’t, he could keep up. Then, as we fatigued further, we couldn’t keep up. I tried his paddle. It seemed to have no grip on the water. It felt like it was broken. And yet that fellow had outdistanced two stronger paddlers with properly designed equipment. Think about that. Small blades, convex or dihedral blades, all those things that make a blade inefficient, may help you to last longer.

Paddles for Effective Propulsion
    When I began paddling kayaks my background was in cycling. At that time the fashion was for very long paddles which were used in a long, low, and leisurely stroke. My immediate response as a cyclist was, "Hey, this bicycle is stuck in high gear!" I was accustomed to pedaling a fast cadence, and I wanted to paddle a fast cadence too. I gravitated to shorter and shorter paddles, until I reached 205 centimeters, which seemed to be the practical lower limit of what I could use with my boat. The shortest paddle one can use is determined by shaft length. Using one’s preferred hand separation--mine is quite wide—there have to be a few centimeters of space between the hand and the blade in order to immerse the blade without wetting the hand. After one has experimentally determined one’s preferred shaft length, the overall length of any given paddle model can be obtained by adding twice the blade length to the preferred shaft length. Testing is very helpful. Sometimes there is a tendency, particularly with wide boats, to hit the gunwale of the kayak with the blade. Wider boats require longer shafts. In my opinion the shaft length should be as short as is practical in order to maximize acceleration and minimize fatigue, especially in headwinds.
    It is awkward to use a very long blade with the high angle stroke necessitated by a short paddle. I suggest seeking out paddles with moderate length blades. If one badly wanted to use a long blade—perhaps to enjoy its extra sculling advantage—one might have to use a slightly longer shaft, and a lower angle stroke. There would be a corresponding increase in fatigue when paddling in headwinds and in all day paddling. Choosing a smaller blade could mitigate that. Smaller blades are less fatiguing than larger blades. Smaller blades don’t give as much support for rolling, so one returns in a circular manner to wanting a moderately narrow, medium length blade, with a short shaft.
    An informal survey of instructors revealed a surprising amount of agreement on the subject of length. We still see many excellent paddlers and instructors using and recommending 225 to 240 centimeter paddles, but now the greater number are using and recommending 205 to 220 centimeter paddles and a high angle stroke. This is in marked contrast to what one would have heard a dozen years ago. One instructor told me that it was axiomatic that students did better, and learned strokes more effectively, with shorter paddles.

Paddle Weight, Strength, and Maintenance
    Although composite paddles have become the norm due to the low weights associated with those materials, you might wish to own a wooden paddle in order to bolster your rolling and bracing skills. The lightest wooden paddles are not objectionably heavy, and are very warm and comfortable in the hand.**** The blade floats its way out of the water, so it acts weightless as it begins its upward arc. In short lengths the swing weight is less important, and wood is a viable option for performance. Wood requires occasional refinishing, but it isn’t difficult to do. A half an hour’s time every once in a while is a small price to pay for the pleasure of enjoying the glowing beauty of a well cared for wooden paddle.
    Composite paddles, particularly those with low density cored blades, are usually lighter than wood (until the recent advent of carbon shaft/wood blade paddles such as the Zephyr upon the marketplace), and may share some of the buoyancy advantage of wood. Some of the new carbon fiber cored blades are particularly attractive.
    One carbon fiber cored paddle in particular stands out from all other paddles for its rolling and sculling performance. The Toksook, designed by Derek Hutchinson, is easier to roll and scull with than any other Euro style paddle I’ve tried. I don’t prefer it, even for rolling and sculling, because its thick double dihedral blade drags badly when sweeping, but no one can deny that the support is awesome. The Toksook has a particularly long blade, and is heavy, so I disliked it for paddling. A person who requires maximum durability, doesn’t mind weight, likes a low angle stroke, and needs the most solid rolling platform available, might prefer one of these.
    One of the toughest tests of a paddle shaft is a poorly executed paddle float rescue. Portly out-of-shape-paddlers with large paddle floats and poor technique replicate the strains one might encounter in using a paddle for a walking bridge between a pier and a ship. Large diameter tubular steel would be the best shaft material for that application. Wood, fiberglass, and carbon fiber are all poor choices for really bad paddle float rescues, though all would be fine if good technique were used.
 
Conclusion
    There is no agreement among experienced paddlers as to what is best, but we are seeing a trend toward shorter paddles. Blade choices vary hugely from individual to individual. I recommend blades of moderate length and moderately narrow width, with an overall paddle length between 205 and 220 centimeters.
    Fiberglass is still the most popular material, and still an excellent choice. Carbon fiber is generally superior to fiberglass except in price. Wood is having a resurgence in popularity. The beauty of wood, its warmth in the hand, and its superior rolling and bracing characteristics have caused many serious paddlers to return to this formerly forgotten material.  We are beginning to see the appearance of paddles with wooden blades and carbon fiber shafts that are competitive in weight with carbon fiber paddles.  These may become very popular as their advantages become known to the public.
    I still like my one speed bicycle analogy. One paddle is one speed. Two paddles are two speeds. I suggest having two good paddles so you can shift gears. One can be your spare when you’re using the other. You might want one slightly longer paddle to be the one you like to use for cruising in favorable conditions. The other might be shorter for ease of paddling into headwinds and for avoiding fatigue on long sessions. Think about the compromises, and pick two paddles. Ten centimeters is a good difference to use between the two.
    What did I select for myself, based upon my testing? I bought a wooden Grey Owl Spindrift (listed in the Products page) in a 215 centimeter length with 60 degree feathering. The cross sectional shape is slightly convex on the back and a flatish dihedral on the power face. It is light, enters the water cleanly, works well with a high angle stroke, and is easy to scull and roll with. I also enjoy the springy feel of the shaft. (My wife uses the same blade, but with the newer carbon fiber shaft in order to reduce the overall weight.)  My other paddle is a wooden Mitchell Sea Blade, which has a shorter, broader blade. The cross sectional shape is slightly convex on the back and flat on the power face. It doesn’t find the proper climb angle for rolling as automatically as the Grey Owl does, but it isn’t bad. The short blade allows me to have my preferred shaft length in a 205 cm paddle, which helps when I have to struggle against a headwind. I tested dozens of paddles, and didn’t miss any rolls. There is no incentive for me to put up with inferior forward stroke performance in order to get better rolls, but since good forward stroke performance and good rolling performance are compatible, why not have both?



**It would be possible to make a composite cored paddle that mimicked the cross sectional shape and volume of wood, and it would behave like wood. This isn’t being generally done yet. The Toksook is the only example of that type of construction that I’m familiar with. The Toksook is available through Wayne Horodowich at the University of Sea Kayaking.
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