Know Your Kayak Under the Water (part 2): Stability Applications

There are many considerations between practicality, safety and desire when we shop for a kayak.  We may look for features that empower us for a realm of high adventure, or opt for a more modest craft to spend a few blissful hours in a tranquil paradise.  Whatever we choose should have features that reach a balance between our aspirations, skills and confidence on the water.  Unfortunately, there is no high tech miracle that will deliver all these things for every paddler.  But instead a game of give and take that forces us to sacrifice coveted qualities we desire for the performance we want.  Hull design is all about tradeoffs.  But kayak designers are using some innovative techniques to seemingly cheat the laws of physics.   In part 1 of this series, we examined the merits of primary and secondary stability and learned the importance of selecting the proper measurement of each to cultivate our skills and piece of mind while considering the consequences of the trade-offs for our choices.  In this article we will examine some real kayaks and identify performance characteristics from their hull features and uncover some tricks designers are using to deliver performance while minimizing sacrificial tradeoffs.

The first kayak we will analyze is a popular recreation kayak targeting novice and casual paddlers with a bit more prowess to take them a bit beyond novice conditions: The Tsunami from Wilderness Systems is the choice of a wide range of paddlers from the very novice to intermediate and delivers a surprising performance when pressed.

A kayak that fills this role must feel comfortable and secure to paddlers whom have never paddled a kayak, and those engaged in a secondary activity like birding or fishing.  So a high degree of primary stability is required.  In exchange for this up-front stability, a substantial wetted surface must be deployed underwater to provide an adequate angle of support for a comfortable stable feel (see Fig A).   The downside to providing this comfortable stability is the substantial drag from the broader wetted hull surface in addition to instability in rough conditions from the primary stability attempting to right itself on the slope of waves.  But it is a designer's job to cheat the laws of physics anyway they can to reclaim performance.  And the designers at Wilderness Systems had a few tricks up their sleeves.

   As we saw in part 1, the theatre of battle between the forces of stability and instability plays out in the form of rotation about the longitudinal axis spaning the length of the kayak.  To remain stable, the kayak must apply righting forces in the form of an opposing torque to this axis to counter the rotational destabilizing forces much like a wrench applies torque on a bolt.  As we know, a longer wrench shaft will apply more torque on the axis.  Moving the righting force away from that axis will allow the hull's beam to be used as leverage to magnify the forces of the primary and secondary stability as illustrated in figure B.  But designers pay a high premium in wetted surface drag if they extend primary stability to the entire width of the hull.  Figure A illustrates a cross-section at the center of the hull's length where the always deployed primary stability support is consuming wetted surface (WS) area.  However, secondary stability is much less costly to the drag of the kayak as it resides undeployed at and above the waterline.  So the kayak's streamline qualities will benefit most from this leverage if secondary stability resides at the furthest distance from the center axis.  As we can see from the figures above, the designers at Wilderness Systems took a bite out of the primary stability area and lowered the secondary stability to quickly deploy when the kayak leans, taking over at the point where the center of gravity pushes the primary stability to the point of capitulation (see figure B).  We can also see the wetspace drag is reduced from this design as the wetted area is reduced.   The handoff to secondary stability will also lend more stability in waves as the destabilizing effects from primary stability are reduced.  But one drawback to locating the secondary stability this low to the water is a jump in the amount of wetted surface drag when a heavy payload makes the kayak sit lower in the water as secondary stability  sitting passively above the waterline is deployed prematurely to bolster buoyancy.

Task of lip changes to rear flotation

As noted above, righting leverage is greatest at the widest point of the kayak, which in the Tsunami is located at the mid point in the hull's length.  So all of the stabilizing magic must take place at the mid point in the length where the hull is widest.  The rest of the hull's length will play little to no part in the stability at all since the leverage possible away from the widest beam is minuscule.  Therefore the totality of the hull fore and aft of the middle is better utilized for other tasks like tracking, decreasing water drag, and providing lift above steep waves.  So the protruding lip that provides secondary stability at the widest point serves a very different purpose of providing buoyancy at he bow and stern to lift them over steep waves and prevent the ends from perling.   This lip  fore and aft also keeps water from splashing on the paddler as waves hit the kayak.  Also notice how the the designers reduced the wetted area fore and aft of the middle.  The designers also added a dome area atop the ends to increase the buoyancy of the ends to reduce the tendency of periling into the waves.  The pointed tops allow the ends to cut to the surface of the wave quickly if they perl without shoveling the water.  These robust design measures at the ends is needed to overcome the lack of rocker the designers sacrificed to put more of the hull's waterline length to work in the water.  As we see later, a rocker design is for waves beyond the targeted market for this kayak, so the designers properly passed on a rocker design.   But they saw the need to bolster the ends to provide a capacity for waves, and this is one of the surprise competencies of the Tsunami.

The Gemini from Valley is an entirely different kayak designed for paddlers with a more advanced skill set.  As such, the designers opted to create a hull at the other end of the tradeoff spectrum to provide more performance and less initial stability, delegating the task of stability to the paddler's skill set.   However, the laws of physics stood directly in the path of their objectives.  They wanted to design a kayak nimble enough to play in the surf and be competent for long distance expeditions.  However, these two objectives put the designers at opposite ends of some significant tradeoffs of the hull design.  A single solution was not possible as these two objectives are irreconcilable without severely diluting their desired specialized performance.  So the designers decided to start from a common base design and spin off two distinct kayaks: the Gemini SP for surf play and the Gemini ST for for sport touring.  For the benefit of our discussion, we will examine the design of both of these kayaks in broader detail to understand the choices the designers faced and the implications on the stability of both kayaks.

Gemini SP underside with peeked keel and sidecut

The Gemini SP by Valley is a surf zone play boat, designed to be nimble in the surf and turn effectively when put on edge.  It is not designed for a comfortable ride over long straight distances for hours on end.  It will smash through opposing waves and surf high atop their crest.  In a surf environment,  primary stability is not needed or desired as we know primary stability will erroneously attempt to right the kayak sideways on sloped surfaces, which is never a good thing.   However, secondary stability is much more desired since it carries a delayed reaction and deploys much deeper into the lean, so a wave will pass before secondary stability can attempt to right the kayak on a slope.  Secondary stability will also protect the paddler form a capsize while edging the kayak and leaning into a wave while side-surfing. Tracking is not as important as turning for a surf zone play boat since it must react quickly and need not hold a straight course for very long.  So the designers created a short 14' 10" (452 cm) kayak with a lot of rocker to turn when on edge and stay above the waves with an upward orientated bow and stern.  However, the tradeoff to this rocker design does not allow the load to be dispersed over the length of the hull, resulting in a hull that concentrates the load at the cockpit.  A necessary sacrifice for the the high degree of coveted rocker.   Normally, the laws of physics would be unkind to such a design as the sagging cockpit would plow the water causing significant drag.   But the designers at Valley were not ready to give up on the kayak's prowess on smoother water.  After all, the goal was to create two similar kayaks for different purposes with similar characteristics.  To make the Gemini SP snappy as well as nimble, they needed to streamline the wetted surface beneath the cockpit to reduce drag.  And the only way to do this was to add buoyancy at the keel with a steep peaked bottom to reduce wetted surface by boosting the kayak a little higher from the keel.   To further reduce the wetted surface area the designers gave it hard chines with a cut-out similar to what we saw in the Tsunami (visible in the picture below).  The picture below also shows a benefit in the substantial amount of secondary stability in reserve above the waterline.  The tradeoff for all this is a reduced primary stability which is not desired in a surf playboat, resulting in an initially unstable feeling kayak that novices would find unsettling, but a high performer for its playground in the surf.

Gemini SP rides high with its rocker and ample sec stability

With less wetted surface the Gemini SP shows surprising speed for this type of kayak.  I was surprised one day on the lake when a friend in his Gemini SP was able to keep up with my Epic 18x on a casual cruise on a calm lake.  Claims that Valley highly touts in their promotional material.  

As a touring kayak, the Gemini ST sports tourer is designed for covering distances over calmer waters and provide the paddler with a more comfortable experience on the water over a longer span of time.  It is the same length of its twin the SP.   A touring kayak must be more efficient and minimize drag.   Given its very different mission, the ST has much less rocker, letting it disperse its load over the length of the kayak so it rides higher with less wetted surface drag.  The tradeoff is a less nimble kayak that does not edge as well and tends to perl into steep oncoming waves.   Unlike its twin, the ST does not need hard chines or a high peeked keel.  For its mission, the designers have given it softer chines with a flatter, low peaked bottom for more primary stability, but not too much, but allows the paddler to take a break, fish, shoot pictures, or relax without the unstable feeling of its twin the SP.   But the designers at Valley similarly did not want to give up on the nimbleness of the ST.  Without the high peeked bottom and the large cut out of the side, the designers had the luxury to bring down the sides of the hull closer to the water for a faster, more responsive secondary stability with a small cut for efficiency.  These curved sides will also lend some nimbleness to this rocker-less design when edging by putting a curve on the water (see part 3 of this series).  But the lack of rocker leaves the ST more susceptible to perl into sharp waves.  Often, manufacturers will compensate by adding more buoyancy to the bow and stern as we see in the SP.  But unlike its twin, the designers  remained true to their objective and sacrificed the surf readiness flotation volume at the ends for reduced drag and the efficiency of a more streamlined design.

So despite the very diverse performance objectives of the Valley Gemini designers, they created two kayaks rather than one to tackle an impossible spectrum of kayak performance goals in a truly unique way.  The complexity of these solutions underscores the value of hull design knowledge so we are able to understand and make intelligent choices from the abundance of sophisticated technology available.  Practically, we can only test a few kayaks on the water in far from ideal conditions.  We have seen how designers make significant tradeoffs to obtain their performance objectives.  But the motive that drives many kayak designers is to create a kayak that will fetch broad appeal so the company can monetize a successful product.  For other designers, its a labor of love they hope to monetize.  But the desires of a paddler lends purpose to a kayak as a tool leveraged to seek a path to their bliss and dreams.  Ideally, the paddler will seek the the empowering technology they need, grow into its characteristics, and find confidence to carry on to the next level.  A tall task for products of broad appeal.  But as paddlers we have choices and the ability to obtain knowledge of the science that goes into these more specialized and capable craft.  As for any endeavor no matter the discipline, the right tool is needed for the task.

In part 3 we will examine elements of hull design related to tracking and edging then dive into the hydrodynamics of skegs and directional hull features.


Copyright 2013 Lyman Copps

Laying the Foundation for Paddling Stronger: Cardiovascular Training Part I

By Stephen Knight

    

We’ve all seen a paddler quickly glide by seemingly with little effort and know it’s because of the hours of hard training.  Your second thought is “my interests are touring and enjoying the water, not going fast”.  However, that thought quickly fades when you lag further behind your group of friends or can’t cover the distance they can. “I paddle a lot but I’m still slow. How come?” The answer is not the amount you paddle, but the how.

     Let’s start with the “how”. Without using a heart rate monitor, we can get a good estimate on your level of exertion by how you’re breathing or the Rate of Perceived Effort (RPE).  Using a 1 to 10 scale with 1 being the easiest, we can see that most recreational paddlers stay within an RPE of 1, 2 or 3. Beyond that, the ability to continue at a higher RPE is very limited.  What’s more, it’s going to take a few minutes or longer to recover from a higher effort.

     Now that we’ve established a way to gauge our effort while paddling, what does that tell us about what is going on within our bodies?

     Taking a cue from our breathing, we can divide our response to exertion into five distinct levels and call them Heart Rate Zones. Each Zone is the body’s response to a diminishing availability of oxygen to the working muscles.  At this point a heart rate monitor would be useful as a means to precisely measure our response to working harder.  However, we’d need to know several other pieces of information and that’s beyond the scope of this article.  For our purposes, the RPE scale is perfect.

Looking at the Zone and RPE table, we see two distinct divisions.  Aerobic (with oxygen) in green, and Anaerobic (without oxygen) in red.  These divisions represent the predominant type of energy generating metabolism going on in the working muscles.  The tipping point or Lactate Threshold (RPE 8) is where the body is losing the ability to deliver sufficient oxygen to sustain the effort.  Although glucose can still be utilized anaerobically to produce energy through an alternative pathway, it is short term and produces lactic acid as a by-product.  The body does not let very much go to waste and lactic acid is no exception.  It’s transported from inside the muscle cells through the blood to the liver as lactate for processing into glucose.  Wait, isn’t that why I get sore after working hard?  No.  Lactic acid has an undeserved reputation for producing residual “muscle burn” or soreness when in fact it’s trauma to muscle cells that is the real culprit.  Another name for this discomfort is Delayed Onset Muscle Soreness or “DOMS”.  Fortunately, it goes away on its own and becomes less frequent with regular exercise. 

Now that we’ve learned how our bodies respond to exertion let’s go back to the original question, “how” are you paddling?  If you spend all of your time at an RPE of 1 or 2 there are definite benefits but your fitness level will still be quite low.  Increasing the intensity to an RPE of 3-4 will provide substantial improvements in your ability to paddle longer with less effort, but it still falls short.  It isn’t until you spend time at an RPE of 5 to 7 that you see significant improvements in your fitness. Training at higher levels of intensity will increase

your lung capacity, stimulate the heart to pump blood more efficiently, deliver more oxygen to the muscles through an expanded capillary bed, develop more efficient energy metabolism, and increase the number of mitochondria in muscle cells.  That’s a pretty enticing return for an investment of effort.  But, is it that easy, just paddle harder? Well, sort of.  There’s a smart way and then there’s a hard way to improve your fitness. We’ll go with a smart way to get good results in my next entry.

Thanks for reading my blog entry for the Carolina Kayak Club.  I’ve been engaged in a number of outdoor activities for most all of my life as a participant and instructor. When not competing in running, bicycle and kayak races, I’m a US Canoe and Kayak Team Paracanoe Coach and work with the Bridge-II-Sports Foundation for Adaptive Sports as the Parakayak Racing Club coach.

Know Your Kayak Under the Water (part 1)

As kayakers, we rely on our boats to impose our will on the water, exhorting pure human power against the wind, tides, and currents.  Beyond our own endurance, we have our kayaks and their carefully designed characteristics to safely and efficiently ferry us to our destination.  However, most paddlers when considering a kayak acquisition look above the waterline when over 90% of its vital characteristics lie below the waterline.  Recently, I looked through manufacturer promotional material for several kayaks.  I found happy paddlers in emotionally provocative colorful pictures as one could imagine with a detailed list of above waterline features.  But found little to nothing substantive about the all important hull design.  Sadly, most paddlers do not understand the design features of their hull and its intricacies.  Above all, the hull is the very essence of a kayak's designed performance.  As individuals that kayak, we have different demands as diverse as the seasons.  And selecting a kayak compatible with our skills and needs is very important.  If one design was perfect for everyone, all kayaks would look alike, and we would not have hundreds of models to choose from.  But hull design is all about trade-offs.  Features that deliver the performance a paddler desires or needs will often require a sacrifice in another area.  Despite how instrumental your kayak's hull is to its performance, precious little is has written about it, leaving kayakers in the dark on exactly how and why their hulls perform as they do, and what to look for in a hull shape when considering a kayak purchase.  In this series of articles I will bring to light the deep dark secrets of hull design in simple terms.  We will examine facets of stability.  Explore hull shapes and features below and above the water line that affect stability and in later articles examine hull characteristics of speed and efficiency for moving through the water.  But first we will establish a premise for our examination of hull designs with some basic physical principles to help us dissect hull shape features.

Of primary importance to our endeavors on the water is stability.   In nearly all watercraft, we look to the design of the hull for stability and must sacrifice streamline efficiency to have it.   However, a kayak will permit the task of stability to be delegated to the skills of the paddler, allowing craft stability to be exchanged for a more streamline performance with lower resistance.  But unless your primary task is powering the craft while providing stability every moment you are on the water, this delegated task may not be willingly accepted by many.   Bird watchers, fishermen, and paddlers out for a relaxing day on the water may desire a kayak that provides a high degree of hull stability.  But at what cost?  And why the tradeoff?

First we will look at what stability actually is.  Our kayaks move and twist on the 2D plane of the water rotating around 2 axes.  Since sea kayaks are long and stand little chance of flipping end over end, lateral rotation is of little consequence. So our only concern is its rotation about its longitudinal axis running the length of the kayak.  When we lean left or right we are applying torque on our kayak to spin about this axis.  As we float upon the water, the weight of our kayak and all its contents is pressed upon the water with a downward force and held in check with an upward opposing buoyancy or (weight displacement force).  If the kayaker is properly centered in the kayak, the center of gravity will go straight down through the axis.  In reaction, the opposing center of buoyancy will move straight through the axis in the upward direction to keep the kayak and its contents in check.  Since these forces pass straight through the axis there is no torque being applied, thus no rotation about it.

If the paddler leans to one side, the center of gravity will move away from the axis and impose a torque upon it.  At this point, the designed features of the hull come in to play to react with an opposing righting force by adding more dry hull volume (floatation) in the water on the side of the lean thus imposing an opposing torque by moving its center of buoyancy off-center in the direction of the lean.   Since the weight of the kayak cannot change, to add dry volume on one side of center requires the kayak to reduce wetted volume on the opposite side.   Buoyancy on the side opposite to the lean is also reduced which helps the center of buoyancy migrate in the direction of the lean.  However, when the kayak runs out of dry volume to put in the water, it can no longer move the center of buoyancy to match the center of gravity.  At that point, an unopposed torque will be applied to the kayak hull and it will capsize.   This is the point of capitulation.

So what can we deduce from these physical facts?  First: a kayak hull has only has a fixed amount of stabilization reserves.  If they are spent early providing primary stability, we can expect the kayak hull to capitulate earlier.  Also, as a long wrench with more leverage can apply more torque  than a shorter wrench, a wider kayak will have more leverage to apply more counteracting torque against a leaning torque.  But widening the beam will dramatically sacrifice speed and increase water drag when the kayak moves.  A tradeoff that must be considered wisely.

 So what are these features that work for us?  What does a featureless hull look like?  Lets examine a featureless hull which is simply a floating cylinder.  Since it is round and featureless, its center of buoyancy will always be in the center and cannot move to either side.  Its perfectly round shape does not allow any more volume to be added to one side or taken from another.   It is the same on both sides all the time.  Consequently, any offset in the center of gravity will generate torque on the cylinder, opposed only by the small forces of the cylinder's inertia, and friction of the water.  Picture yourself standing on a perfectly round floating tree trunk.

Since have a stability budget, how do we spend it?   If you fish or birdwatch, and paddling is your secondary purpose, or you just want a stable, secure experience in calm conditions, you may want to spend a good part of your stability budget on primary stability.  Primary stability is the instantaneous ability of the craft to apply a righting force to a leaning motion.  Kayaks with high primary stability feel stable initially as any leaning is met with an instantaneous counterforce.   In order to accomplish this, primary stability must be located in the wetted volume of the hull.  High primary stability hulls will have a flattened bottom with possibly a slight "V" or gentle rounded shape.  As such, the hull size below the waterline is larger and drag from water friction is rather high, affecting performance.  Since much of the stability budget is spent on this primary stability, there is less of a secondary stability reaction.  But high primary stability will require more leverage, thus a larger stability budget which must be bought by widening the beam (width) so the hull can achieve enough righting torque on the axis with a longer lever (remember the wrench).  Typically, high primary stability kayaks are wide and short as they do not need an excessive waterline for a kayak that is not designed for blazing speed or cover a lot of distance.  But they are a lot of fun, very practical in rivers and small lakes, swamps, and estuaries and highly maneuverable.  But, a high primary stability exposes the kayak to a serious side effect.  In our theoretical illustration above, we observed the mechanism of stability as a function of the kayak's flotation and the water surface.  We know the kayak will attempt to bring itself level to the surface of the water.  But the surface of the water is often not level (the slope of a wave).  So a kayak with high initial stability can right itself sideways to a small degree; enough to introduce considerable instability in rough water, requiring mitigation with bracing skills from the paddler.  But, for paddlers who rarely venture into rough waters and have no desire to travel far or fast, a primary stability kayak will be a fine investment for a leisurely enjoyable ride.  Performance paddlers will find themselves fighting a sharply increasing  drag as they ramp up speed.  The increase in speed will hit a wall as the kayak reaches its maximum hull speed (explained in a later article).

A kayak facing rough seas will need to minimize the instability side effect from its primary stability, and reserve its stability budget for secondary stability.  Unlike primary stability, secondary stability will not respond instantaneously but apply stability further into the lean.  Secondary stability also exhibits less of the destabilizing behavior in waves since the hull will not react until much further into the lean.  Unlike primary stability, secondary stability assets are in the dry volume of the hull above the waterline.  In the first illustration above, notice how the "V" concentrates most of the flotation in the center, while the flotation at the extremities is pushed out of the water into the dry area of the hull.  This is the secondary stability area in reserve.  Since the dominate flotation force is in the center, the kayak will pivot about it and feel initially unstable until the secondary stability is deployed.  In the second illustration, when the kayak rotates about its axis, dry volume is deployed into the water bolstering flotation at the edge of the kayak, which in turn moves the center of buoyancy to counteract the leaning force.  Since secondary stability assets are stored above the waterline, these kayaks  enjoy an added advantage of a more streamlined hull with much less wetted hull surface resulting in far less drag from water friction when the secondary stability is not deployed.  Secondary stability kayaks cater to more advanced paddlers seeking performance.  In many models, manufacturers will further narrow the beam (width) considerably stripping much of its righting force leverage.  And by this action, delegate much of task of stability to the bracing skills of the paddler in exchange for a considerable increase in performance.  Manufactures may also choose a more rounded hull without a "V".  But the stability principles are the same with more rounded surfaces offering less primary and more secondary stability, with flatter rounded bottoms offering a higher degree of primary stability.  Novice paddlers will find secondary stability kayaks deceptively unstable and unsettling.  With a much more narrow beam, these kayaks will have a much smaller stability budget, but will store most of this tighter stability in reserve for a time when it is really needed.

To illustrate primary stability and secondary stability I presented two mutually exclusive theoretical kayaks.  But in reality, no kayak will have all of one and none of the other.  All hundred or so kayak models will fall somewhere in between catering to many skill levels and a wide range of venues and conditions.  When a paddler chooses where they want to spend their stability budget, they should deliberate long and hard to find the kayak that best suits their needs in the near term and longer term.  Also consider where you are going to paddle and where you want to paddle.  They must also assess their skills and allow room for improvement.  A kayak designed for calm conditions can also perform well in challenging conditions if used with proper skills.  When I purchase a kayak, I am initially a little unstable and grow into its characteristics as my skills improve.   Paddlers for whom the kayak is a vehicle for another purpose or activity may want a lot of primary stability so they can focus on their secondary activity.   Kayakers wanting performance with the intention of piling up a lot of distance will want a performance kayak with a low drag.  Paddling a considerable distance with a higher drag hull can feel like towing a second boat.  A day on the water with a prospective kayak is better than a short test paddle.  When shopping for a kayak, try a lot boats.  You may just fall in love or learn a little more about who your are on the water.

In the next article of this series, we will apply some of our new found knowledge to examine the stability characteristics of a number of actual hull shapes.

Sources:
http://www.rcwarships.com/rcwarships/nwc/stability.html

Copyright 2012 Lyman A Copps

Big Fun in Small Surf

A few kayakers you may know ventured into some winter surf. I am still without drysuit (hurry, hurry with the replacement, Kokatat!) so I came out with my camera to shoot some photos.

The surf that day was quite mild (1-2 feet) and mushy, but folks still had a great time. What's interesting to me is how much variety, fun, and challenge there is in the small stuff. As you look at these photos, it's good to consider how high a two foot wave can look when it's cresting above you
and you're seated in your kayak. Why, it can block your view! Imagine, then, what seriously big surf must look like--its weight, muscle, force. When I read about the stuff, say, Freya Hoffmeister has paddled, I am deeply humbled by both the ocean and true courage.

Take a look.

 Here's the start to the day. This is often how we view the water, standing. It doesn't look dramatic, just a calm day at the beach.

 When you're launched and just past the breakers, you can see how even small swell appears to swallow the kayak.

 From shore, standing, you might not even notice the swell. Look at the photo. You don't see the swell clearly with the eye. But you can tell it's there once you realize that Chris and Lee are in their kayaks, not swimming.

 When the wave crests, it looks really big! This wave may have crested at just above 2 feet. But look
how it appears from the vantage of Dawn, the kayaker!

 And, even the small stuff is fun to surf, lots of energy and great rides.

 Sit on tops, like Frank's, are a lot of fun in the surf. If you don't like to paddle a decked kayak, and aren't interested in learning to roll, these kayaks are terrific options, and fun in the surf!

 This photo looks dramatic! Lee has just finished surfing and now it's time to brace!

 With a nice low brace, Lee and his kayak bounce through the soup. It's counterintuitive, but leaning in to the foam pile with a solid low brace keeps your kayak upright.

Here, Chris is finished surfing and ready to brace.

 Frank zooms down a nice one!

 I like this photo because it looks so COLD. I think that's a stand up paddle boarder behind Lee. Lots of the SUP crowd is out these days.

 More pretty ones.

 A 1.5-2 foot wave can be truly fun. Look at the ride Dawn's catching!

 Whee!

 This is a pic of Dawn doing a cool layback high brace she learned at Sea Kayak Virginia.
I mean to try these sometime.

So don't think you need massive surf to have a good time in the surf zone.  Most sea kayakers wouldn't know what to do with a wave that's three to four times the size of the one in the photo.

Small surf is fun.

Finding Stability in a Sea of Chaos

As we indulge the sounds of life, a mosaic of diverse vibrations, notes, and beats play upon our ears at times orchestrated with purpose, other times randomly.   With the experience of life, we perceive these sounds and wire our minds to react to them in thoughtful predictable ways.   The sea is not unlike our terrestrial world.  As we watch the ocean, we see another type of concert manifested in the waves with rhythmic vibrations, harmonics and beats similar to the sounds we surf with our ears.  As kayakers, we are afforded the unique opportunity to become part of the music of the sea.  Where every other water going vessel passively opposes the sea's forces, the kayak alone is able to interpret and play upon each wave with elegance and precision, realizing remarkable stability for watercraft of such narrow proportions.  Last year I faced faced a situation of hostile conditions far out at sea for more than 10 hours (see "50 miles at sea") and learned in course of the trip, rather than futilely react to each wave, there was a opportunity to assimilate with the rhythms of the sea and feel stable in the midst of chaos using my paddle as an instrument, and my cadence as a verse.

But the waves and motions of the sea are even more complex and diverse than a symphony orchestra.  Waves originate from many sources and many directions, close by from boats to storms and winds hundreds and thousands of miles away, and even reflect from rocks and shorelines and move in opposite directions making the water very confused and difficult for kayaks.  A paddler unfamiliar with such conditions, like a person encountering a loud strange and unanticipated sound will react defensively with a thoughtless opposing reaction.  As we gain knowledge of unfamiliar sounds, we respond with a predictable and well thought out action.  Similarly, as kayakers, we will encounter difficult conditions many times and must develop ways to handle these situations.  Especially in a long trip where we may face difficult conditions for hours and days at a time, we do not have the luxury to react to each wave.

Large cruise ships use sophisticated stabilization systems with bracing fins that work exactly in the same manner as a kayaker braces with a paddle to provide remarkable stability in rough seas.  As its complex computer algorithms interpret the sea's motions and rhythms, so do our minds in an even more eloquent way with the the ability to anticipate the conditions and instinctually apply the proper stabilizing actions.

The kayak itself has little innate stability.  Although wider beam kayaks for the novice possess a higher degree of primary stability,  nothing comes close to the skills of a skillful paddler.  In wavy conditions, primary stability works against the paddler and shows its weakness inherent in every other craft as it characteristically applies a righting force to bring the kayak level to the surface of the water.  If that surface is on the slope of a wave, the kayak's primary stability will actually attempt to right the kayak more sideways which can be seriously destabilizing in the moving motion of the waves.  In challenging conditions, lower primary stability is more desirable as the paddler assumes the responsibility for providing the stability.  But every kayak still has some primary stability, and the paddler will be pressed to mitigate the affects of the waves on that primary stability in addition to the other effects by applying a brace to each stroke.

Applying a brace to the stroke is a simple matter slightly angling the blade downward during the stroke.   Angling the blade will add a downward force component in addition to a forward thrust.  Adjusting the downward angle of the paddle can be done very quickly.  Often times the paddler will need to try a number of angle settings to find just the right bracing strength.  But once the right angle is found, its normally good for the wave set and should be noted for similar reoccurring sets of waves.  If more bracing force is required to cross over a sharply pointed wave or through a whitecap break, a downward pry can be added to the stroke by pushing straight down on the braced blade during a stroke.  The pry can be used only when a brace is applied to the stroke.  Otherwise, the blade will knife downward and possibly compromise stability.  If a wave hitting the kayak requires a pry on a brace, the paddler should be ready to brace quickly on the other side to address a possible abnormally harsh transition to the downward slope with a temporary shift to a fast cadence.   As I paddled long hours in rough conditions, I was periodically hit by isolated waves which posed a problem, requiring a fast cadence until the wave passed.  On a couple of occasions  a wave broke over my bow, causing the kayak to spin off course like a compass needle.  The fast cadence possibly averted a capsize far from shore.    

As waves travel through the ocean they combine and cancel each other out.  Over a distance, the resulting set of waves normalize into a consistant procession known as a "wave train".  The waves further congregate into groups like harmonics from a string instrument, which  called "sets".  The kayaker will notice groups of similar size waves passing in cycles as wave sets come and go.  The paddler will need to adjust to changing wave sets by altering the brace angle and cadence to match the oncoming set of waves and make fine adjustments.  Through a number of cycles the paddler will notice a pattern which can be anticipated and formulated into a strategy to be used at any time in the future.  As we learn to anticipate the notes of songs we hear many times, paddlers on longer trips will have the ability to predict when wave sets will arrive and structure tasks around the arrival of specific sets of waves.
As a padder moves through a rough conditions with the wave train at the beam, the kayak will transition between the upward and downward slopes of each wave.   With a normalized wave train, the waves are spaced consistency.   The paddler may use this to an advantage, by matching their stroke cadence to the consistant period of the wave train.  A slower cadence is used for longer wave periods.  A faster cadence is used for more confused conditions with sharp pointed waves.  When in doubt, I always start with a faster cadence and adjust downward to empirically match the conditions.  The transition between braces should match the crest and the trough where the slope changes.  After a while I was able to develop an instinct to match my cadence to the wave train and develop a strategy for a number of conditions and realize a feeling of stability and confidence in a sea of chaos as these motions became more instinctual.

As kayakers, the chorus of the sea summons our skills and intuition to artfully ply confused waters with uncommon grace and dexterity while bearing witness to its every nuance like no other craft.  As a musician contributes to a song, the kayaker flows with the beats and rhythms of the sea, wielding their paddle in a special art of seamanship as a small contributor in the greatest composition.


Copyright 2012 Lyman A Copps

Kayak Katamaran Kabana

10/25/2012

I am ever in search of the perfect camping solution for different situations, and a recent post by FastYak on the CKC forum shook loose some ideas I had about a floating camping set up. I'm not thinking of a pontoon boat or a platform with flotation that could be towed by kayak to the location of one's choice. My idea is similar but more compact, which is appropriate for a small boat. 

Mountaineering and the relatively new sport of tree climbing/camping make use of suspended sleeping platforms or portaledges like this.  I have no idea how they transport the things but am assuming they don't climb up the wall or tree with the fully assembled platform hanging off their backs. Presumably it comes apart like a tent and can be stored more compactly. 

The thought of sleeping suspended that high is absolutely terrifying to me.  Being wide awake is no more comforting. I can barely even stand to look at the photos. However, the platform, minus the suspension straps is an idea that could possibly be modified for paddling. 

Such a kayaking platform would consist of two side poles and a spreader bar on each end (or vice versa) between which some kind of taught strong fabric is strung. The whole thing would be securely supported across the back and front decks of two kayaks (the "pontoons"). To get an idea of how the crossbars might work have a look at this photo of two double kayaks attached together like a catamaran for use with a Balogh Sail. For the Kayak Katamaran Kabana there would only be 2 crossbars. There would be some permanent mounting base on the kayak to which the poles would be attached. Pole length would be determined by the desired size, structural requirements and engineering limitations of the materials. The longitudinal bars would of course have to be attached in some way to the crossbars.

It could be a camping platform, sun deck, swimming/diving/fishing platform, etc. A tent could be erected on top. To reduce weight and bulk it might even be possible to use strong specially constructed paddles for 2 of the poles with those also serving as the spare paddles. Other dual purpose features could possibly be incorporated as well. Perhaps a folded configuration of the fabric could double as a sail with poles or pole parts serving as mast, boom or spar. Also, in heavy wave conditions having the two kayaks securely attached to each other could provide additional stability, more like a catamaran. 

If designed right it could be taken down and the fabric stowed in a hatch with the poles stored on deck as are spare paddles. Since 2 kayaks are needed for support there will be 2 kayakers who need a place to lay their heads. So a double platform like this Black Diamond Cliff Cabana would be needed.  For mountaineering these platforms must be over-engineered for strength given the consequences of failure. That also makes them heavy, the Cliff Cabana weighing about 20 pounds. Seems to me a kayak supported platform would not have to be that heavy. 

Has my imagination run wild? Probably yes. But it would be so cool to have a Kayak Katamaran Kabana - paddle over to a unique corner of the marsh or swamp, drop anchor or tie off to a tree, set up the platform and spend the night gently rocked to sleep on the water.

Any mechanical, structural or materials engineers out there with any ideas about how to do this?

Beautiful Contrarians

Sooner or later someone will say to you, “Everything about learning to kayak is so counterintuitive.” For instance, to turn your kayak, you do all the work on the side opposite from the direction you wish to turn; to keep your kayak from turning over in a wave, you lean in to the wave, sometimes until you are buried by it, in order to stay upright; to roll, you keep your head in the water until the end. At first these things feel completely, dangerously unnatural. Why? Because they are unnatural-- at least to our land brains.

Maybe, like me, after you've kayaked a bit, you’ll begin to discover that your land intuition isn’t all it’s cracked up to be, and that by learning to kayak, your brain becomes engaged in the entire world differently, all the time, not just when you're on the water. Perhaps when you are wanting to steer a situation the way you would steer a car, you think: no, this situation requires my kayak brain, and to steer this situation, I must work on the opposite side, even though it is counterintuitive.  Perhaps someone pushes you around and you think it’s time to hide, but you learn to lean in hard against whatever’s coming at you in order to stay upright. 

Or maybe you find yourself suddenly upside down and submerged and wanting to panic, but kayaking has taught you that you’re fine, you can hang out a while without worry or panic, only to roll back up, and keep paddling forward.

Kayaking may be counterintuitive, but the lessons transfer well to the non kayaking side of life too. 

A Harbinger for an Ancient Legacy

Recently, the science of kayak hull design has taken and interesting turn which brings together aspects of the kayak and surfski into new exciting high performance craft that promises to shape the future and change the way we paddle.  In this article, I present some background information and dive into design features of the Epic 18x which I believe is the most compelling hybrid design to date.

The kayak is a remarkable invention of the Inuit people allowing them to thrive in barren, hostile lands, not otherwise suitable for habitation.   This powerful tool while bountiful with its benefits, demanded a discipline and strict set of age old skills.  Modern renditions of the kayak gave this remarkable craft to the masses and introduced them to the rich Greenland traditions and discipline.  But nothing from the past is immune to the scrutiny of science, as paddlers demanded greater performance and mastery of the seas.  As science and technology have influenced the kayak, the surfski, having come from a very different past, faced an even more profound transformation, producing remarkable paddle craft capable of achieving high speeds on the rough ocean, not only squeezing efficiency from the paddler's every stroke, but augmenting it with energy captured from the sea itself.  As the quest for kayak speed progressed, high speed flat water racing kayaks emerged, achieving high speeds, but leaving the paddler with a much less seaworthy craft as optimizations for speed sculpted away its traditional rough water handling features.   However, the kayak industry is now taking a long look at the surfski and finding ways to adopt its remarkable design elements.  Recently, one kayak manufacturer introduced an exciting new iteration of its kayak that is every bit a kayak above the waterline, but every bit a surfski below the waterline.  While new designs are common, the paddling community took notice as this new radical design achieved staggering speeds and proved itself a formidable expedition kayak.   However, as with the racing kayak, there are always tradeoffs in exchange for gains.  But, for the first time, a near hybrid design emerged, capable of being paddled like a kayak or surfski on the ocean,  casting a shadow on the pedigree of two rich and storied legacies and their legendary disciplines.

The surf ski sprouted from modern western culture along the coast of 20th century Australia.  As the populations ventured into the turbulent surf,  a need arose for a suitable lifesaving craft capable of negotiating the surf.  In New South Wales, Harry McLaren and his brother Jack in 1916 built sit atop, hand paddle boards to navigate the family's oyster beds.   Variations of these craft were later used for lifesaving and proved much more agile than 5 person surf boats that required a high degree of skill.   In time, lifesavers realized a double surf ski could do most everything a life boat could.  These early surf skis were very wide and bare little resemblance to those in use today. With little reverence for its past, the surf ski was transformed into a high speed, ocean going paddle craft for recreational and racing purposes.  The length grew to increase the waterline for speed and provide more stability when smashing through the waves.  To reduce drag, hulls were narrowed and the "swede" hull design which places the point of maximum beam behind the cockpit was implemented.  With the point of maximum beam behind the cockpit, water inertia and friction on the hull is reduced as water is moved out of the way more slowly over a longer wedge.  The swede hull also places the paddler closer to the water for a better vertical stroke by locating the cockpit in a more narrow part of the hull.  The iconic pointed ends and most of the rocker that allowed Greenland kayaks to keep their bows above the waves in rough seas are sacrificed in favor of a much longer waterline for speed.  To replace the missing rocker and the up-swept ends, the bow was made much more buoyant by squaring it off and making it taller.  These efficiencies, the lack of rocker and extended hull length, allows surfskis to put their full length on the water and achieve a greater bow angle and more effectively harness the gravity off the face of a wave to add significant speed to the overall average.  Wave riding skills are an intricate part of surfski discipline.  Surf skis have no edging control, so secondary stability and chines in the hull that produce a distinct secondary stability are not required by surfski technique.  Instead, a smooth rounded hull is used to reduce the wetted surface, thereby further reducing water friction.  But this requires more technique and a strict discipline to keep them upright.  Stability is attained through bracing and proper posture centered over the keel.  Typically, the paddler will lean forward to utilize the strongest torso muscles with knees close together, head pointed forward, chin up.  A rudder provides all directional movement and must be available at all times.  Surfski designs increased rudder availability by relocating the rudder forward of the stern to keep it in the water on steep waves that often lift the stern.  Unlike kayaks, surf skis have not attained a payload capacity and serve a short duration paddling purpose.  Surfskis are very different from a kayaks and demand a different skill set and paddling style.  Surf ski Discipline, and technique has evolved into two primary goals: keeping upright, and maximizing forward thrust.  Sprint kayaks share a similar technique with surfskis on flat water.  A proper stroke is crucial: Blade entry, catch, and follow through.  Also important, is a technique to maximize the efficient transfer of energy to the hull.  Surfskis are paddled with a wing paddle.  Forward lean with strong torso rotation is needed to utilize the core muscles for a sustained strong drive.  Good technique will propagate the rotation to the seat and transmit the energy through the legs which pump up and down to deliver energy to the hull through the foot pegs. Surfskis are not rolled, but are easily remounted from deep water.

As the relentless persistence of science sculpted the kayak,  new designs took shape along the same path of technological optimization as the surfski.  However, the purpose of the kayak is very different.  Not primarily designed for speed, the kayak was created for much more practical purposes and survival, including transportation, hunting, and fishing in rough waters, requiring maneuverability, stealth, and high degree of seaworthiness.  The Inuits solution: a highly rockered, upward pointed hull ends kept the kayak from diving into large waves, but reduced the waterline of the craft which was not that important.  The pronounced "V" shape of its hull and chines had little primary stability, but added a reliable secondary stability. The pronounced rockered "V" shaped hull also helped these kayaks track straight, and turn easy with edging.  Greenland kayaks have no skeg or rudder.  However, the pronounced "V" adds wetted surface and water friction to the hull which is not a problem for the Inuit style kayak.   East Greenland kayaks were flatter with little rocker giving them more speed with a longer waterline, but were less suitable for rougher waters as the rockerless pointed bow did not have enough buoyancy to lift above the waves.  Greenland kayaks fit snug to the paddler allowing a more symbiotic relation between paddler and craft for easy, quicker edging control and rolling in the event of a capsize. However, they had little room for gear.  Unlike surfskis, kayaks do not require a highly disciplined posture and steep paddle angle.  A lower paddle angle allows a wide unobstructed view angle for hunting, fishing, and keeping other paddlers in sight.  Kayaks can be righted with a brace or a roll.  Historically, the Inuits had no method for reentering their kayaks, since being separated from one's kayak meant certain death in the ice cold waters.  Their very lives relied on their rolls and other righting skills.  Modern kayaking allows the wet exit as a last line safety measure, in turn several methods for kayak reentry were added.   British style kayaks brought the kayak to the masses, while attempting to retain the spirit and characteristics of the original Greenland design.  The symbiotic fit is exchanged for a high volume hull to accommodate a generous amount of gear and paddlers of all shapes and sizes.  Thigh braces restore some of the body extension fit of Greenland kayaks.  West coast kayaks from the western American coast similarly retain the pointed bow and rocker, but add a rudder to a flattened stern to reduce weather-cocking in the high winds of the western American waters.

The designs and techniques of kayaks and surfskis evolved separately and are very different.  As they differ in their purpose, their benefits are mutually exclusive to each other.  Paddlers are left at a fork in the road to decide what they want and what they are willing to live without.  Similarly, their circles of paddlers are divided along the same lines.  Slowly, kayak manufactures started dabbling with design aspects of both paddle craft, adopting bits and pieces at a time.  To make a truly hybrid design was a difficult task fought with several technical challenges.  Moreover, they each require different skill sets and disciplines.  Kayak manufacturers began to adopt a very limited number of surfski features, yielding limited gains since these features on a kayak could not be paddled in the manner for which they were originally designed.   At Epic Kayaks, the two founders,  both surf ski champions, over a period of years, ventured so far as to entirely do away with the kayak hull in favor of a swede style surf ski hull in their 18x and 16x models, resulting in kayaks that bare little to no resemblance to their traditional roots, and perform far different than kayaks of Greenland lineage.  They were not the first to try this, but they went further by designing every facit of the craft to give surfski and kayak paddlers what they need to paddle the kayak in the manner befitting both crafts.
 
To satisfy surfski paddlers a reliable rudder that stays submerged and engaged in heavy waves was needed.  While a bottom mounted rudder works quite well for both uses, it cannot be retracted and is therefore unsuitable for most kayak purposes.  The most difficult task for Epic was coming up with a rudder design that would satisfy surfski requirements and fold away to preserve a kayak experience.  Their solution led them down a path to a rudder design unlike any other.  The stern of the hull was severed and turned into the movable portion of the rudder, housing a retractable spring loaded surfski blade, which could be extended from the bottom, forward from the stern.  When not used, the blade retracted into the stern section which in turn, locked into the center position to become the ridged stern of the kayak.  Their solution raised eyebrows in the industry.  While not a perfect surfski rudder, it went a long way to satisfy requirements of a hybrid craft and solved a long standing rudder problem of surfskis and kayaks with a spring retractable blade that moves out of the way when hit by an obstacle, and returns to place when the obstacle was gone.  Obstacles cause standard kayak rudders to kick up and not reset.  Standard surfski rudders just break off unless a stern mounted surf rudder is used.

Epic also did away with the iconic pointed bow and stern of a kayak in favor of the swede surfski hull with an elongated water line and a large  buoyant bow to keep it from burying under the waves.  The large single continuous foot brace facilitates energy transfer through the legs, and elongated cockpit coaming to allow the paddler to easily paddle the kayak like a kayak or surfski/racing K1 with plenty of room to extend the knees through the opening of the coaming enabling the paddler to pump energy into the hull with the legs and rotate down to the seat.  Padded knee holds just under the coaming sides allow the paddler to quickly switch from a surf ski posture to brace for a roll in the event of a capsize.  For a more kayak feel, the seat could be slid forward to allow a smaller paddler's legs to go further under the deck to better contact the hull for bracing and rolling.   Epic designed the seat to retain the functionality and feel of both a kayak and surfski, with smooth bare contoured fiberglass, allowing the surfski paddler a smooth surface to rotate on the seat to engage the lower back muscles and drive energy through the large foot brace.   Like many greenland style kayaks and surfskis, the back is low with little back support.  There is a lumbar pad for the lower back that does an adequate job of support while allowing a good layback roll.   Paddle blade cut-outs on the forward deck were added so the surfski paddler can initiate the catch phase with a vertical stroke close to the hull.  For the kayaker, the craft performed like a kayak responding well to edging, and very easy to roll.  However, as the large coaming provides the surfski paddler with extra room, this further reduces the symbiotic relationship kayak paddlers have with their kayaks, leaving the kayak paddler to alter their bracing technique to grip the undersides of the large coaming with the knees.  The large coaming may also let the paddler come out of the seat during a roll if the paddler does not sufficiently brace their knees against the sides of the cockpit.  To compensate, Epic heavily padded the underside of the deck around the front and sides of the cockpit.  They also put the seat on an ajustable track.  With the lower wetted rounded hull design, the kayak does not hold its course as well with the rudder up, but the rudder is extremely effective in all conditions.  The surfski paddler has what is needed to assume a proper posture, paddle stroke, plus a  reliable forward mounted rudder.  The hull responds like a surfski hull in the sea as it is able to catch waves and not bounce from the bow in rough seas like a high rocker kayak.  The rounded swede hull will likely unsettle beginner and intermediate paddlers initially in rough conditions with its much lower primary stability.  However, when loaded for an expedition, the kayak is quite stable, and rides comfortably at the expense of much of its blazing speed when riding empty.  To capture a little more secondary stability, Epic flared out the gunwales above the waterline behind the cockpit at the widest point of the kayak where the secondary stability emanates.  If the kayak does capsize,  it rolls very easily.  Paddlers of all types will enjoy being placed closer to the water as surfski paddlers expect for their vertical stroke since the cockpit is at a narrower point in the hull.  The 18x is not a beginner kayak, but is one a paddler can grow into and not outgrow.

For expedition use, the kayak rides very stable in the water.  The elongated cockpit makes it very easy to exit and enter.  The newer latch style hatches hold tighter and keep the compartments dryer.  They are also very easy to open and secure shut.  The hinged day hatch is especially convenient which stays fastened and has only one latch.

In an industry with hundreds of kayaks of different shapes, sizes, and specializations, the introduction of a new quirky looking design hardly raises much notice.  However, in 2009, paddler Frya Hoffmeister circumnavigated the continent of Australia (8570 miles) in an Epic 18x sport, and shaved more than a month off the time of the only other previous successful attempt by Paul Caffyn.   The paddling community finally accepted the Epic 18x as a serious expedition kayak and began to debate the merits of fast expedition kayaks.  Epic later went full circle and introduced the V8 surfski which adds a surfski top to the "18x Sport" kayak hull.  While this new kayak could never be the perfect solution or satisfy all the intricate demands of both types of craft, it did integrate the spirit of both a kayak and a surfski in an interesting way.  Harnessing all the benefits of this design will place extra demands on the paddler to expand their skill set to encompass at least a subset of kayak and surski techniques.  For their efforts, the paddler can wield a full featured kayak with the speed and prowess of a surfski when empty that settles down to a stable serious expedition kayak when loaded.

These are exciting times to be a paddler with advances in water dynamics and the melding of kayak and surfski technologies.  Only the future will tell if the Epic design will stand as a milestone in the evolution of the kayak, or be seen as a first deep foray into the realm of a true hybrid craft.  Several kayaks have penetrated the market utilizing aspects of both technologies in their own creative ways.  With the success of the Epic 18x, we will certainly see manufacturers committed to produce more hybrid type craft to take paddlers farther and faster.  Along this journey, paddlers will find they too must evolve to meet the skill set demands of these new craft.  Farther down the road refinements will likely mainstream hybrid design kayaks and push kayakers farther away from a 4000 year old legacy and discipline into one created for the modern age.  Only the future will tell if the traditional kayak will fade into irrelevance and be relegated to the romantic fascination of a few.

Copyright 2012 Lyman A Copps