Coastal Kayak - Article: How To Choose a Kayak

Buying a kayak is easy, choosing the right one for your personal needs is more difficult. How many times have you heard that this is the best, the most stable, the most seaworthy kayak ever built? How many times was this true? There is a wide range of sea kayaks and sea going kayaks to choose from, each designed for a different range of needs. Some kayaks are better suited to river as well as sea use, while others don't fare too well on tight rivers, yet excel on the open ocean. If this is your first kayak, take time to consider the points below. This should help you make the best possible choice. The section on the technical aspects of kayaks will help those wanting to understand kayak design and the major factors that effect kayak performance.

Always keep in mind what you want from the kayak, where you intend using it and what effort you are willing to put in, in order to get the most out of your kayak. Remember that novice and even more experienced paddlers often have difficulties appreciating and distinguishing between the subtle differences of kayaks. Narrow kayaks with long upswept bows always look faster, while wider kayaks look slower - often preconceived perceptions block the objective testing of kayaks. Kayakers are generally a friendly bunch, so stop them on the beach and ask them what they think of the kayak they are paddling and what they think of other kayaks. Take note of the difference between sea going kayaks, sea kayaks and recreational kayaks. In choosing a kayak you will have to determine what amount of effort you are willing to put in, what skills you are willing and capable of gaining, taking into consideration what you want to use the kayak for.

What kind of effort do you wish to make?
There are 3 kinds of effort involved in kayaking:
1. firstly lifting and carrying the kayak to get it to the water
2. secondly the effort involved to learn the skill of using the kayak
3. thirdly the effort involved in the actual paddling, including the comfort of the kayak

Unfortunately, there is no kayak that can offer the best of all of the above, so you will need to work out which of these is the most important for you personally. Each kayak on the market is designed to provide a different mix of compromises for different paddlers.

1) LIFTING AND CARRYING:
Will the hassle of carrying the kayak stop you from enjoying a paddle? Especially if you intend paddling alone, check that you can handle the kayak as difficulty increases with weight and with length. Below 22 kg most people can handle, above 30kg is difficult for one person (even the strong). Contrary to popular belief the weight of the kayak does not have a significant effect on the speed of the kayak in the water. The lightness of the racing kayaks is more a concern for carrying (portage), and initial acceleration, not actual cruising speed.

Possible compromises to enable easier handling are:
1) choose smaller, more basic, with less performance;
2) pay more money for a lighter material of construction;
3) buy a kayak trolley - it will help the carrying, but not the lifting.
If you only want a kayak for birdwatching on your local lagoon and for gaining access to those tight reed sections, then going small, basic and light is the ideal kayak, and it is not a compromise.

2) LEARNING THE SKILLS:
Do you want to kayak for occasional fun, as a hobby, or for the challenge? Do you have the time to learn the skills or are you only paddling during holidays?

a) Easy to Learn:
Kayaks that are designed to be easy to learn generally have a high primary stability (this is a measure of how hard it is to lean the kayak from its upright position). These kayaks are often marketed as "recreational" kayaks and are normally quite wide (generally over 70 cm), and relatively short (mostly under 4 m). You will be able to paddle them the first time you try and there will be a limited learning of skills. Children can paddle these kayaks (depending on their size). Recreational kayaks tend to be slower, mostly as a result of their increased width, and either lack maneuverability or tracking, and therefore should not be paddled in conditions that are more challenging. They often don't have rudders and have fewer features than sea kayaks. Casual recreational kayaks, although more stable, have limited rough weather capabilities. Examples of these kayaks are the Perception Minnow and to a lesser extent the Swing.

b) More of a hobby:
The initial ease of learning may be less important to you than being able to use your kayak in a wider range of conditions or places as your expertise increases. In this case you also need to consider the secondary stability of the kayak. This is a measure of how easy it is to tip the kayak over (or keep it upright), once you are no longer completely vertical. A kayak with good secondary stability can often cope better with rougher conditions, provided the paddler has learnt how to handle the kayak in these conditions. Touring or expedition kayaks often have good secondary stability as opposed to good initial stability. They tend to be more narrow, and longer, than recreational kayaks. This makes them faster - rather think of it as requiring less effort to paddle. You should also be able to paddle your touring kayak the first time you try, and still be able to push your limits well into the future.

c) More of a sport:
The most challenging kayaks to learn to paddle are the more specialized kayaks - the most common specialization's being racing, and white water paddling. If you decide to choose one of these - you will definitely be limiting your paddling.
Racing kayaks are specialized for the type of water - surfski's are used on the sea, and K1 (or K2) kayaks are used on rivers. They tend to be very narrow (around 50 cm at the deck, less on the waterline) and long (more than 5 meters). Racing kayaks are designed to go forwards in a straight line as fast as possible. In order to change direction a rudder is needed, as the kayaks are designed to track. Staying upright is achieved through a combination of forward motion and developing a sense of balance (like a bicycle). This skill can take weeks or months to master. Taller people with broader shoulders, who carry their weight in the top part of the body, can sometimes have a lot more difficulty getting this right, as a small change in position of the body leverages the kayak over, and the paddler falls out. Generally speaking women have better balance than men have. Surfski's cannot be paddled in shallow water as they have a rudder attached to the keel, which can easily be damaged or broken off. K1's are very unstable and nearly impossible to control in typical sea conditions. The benefit of this type of kayak is that there are normally races and time trials to participate in - the sport is organised.

White water kayaks are almost the opposite in design of the racing kayaks - they are normally short (less than 3 metres), and are designed to be as maneuverable as possible. They do not track well in a straight line, and while they can be used for surfing in addition to playing in the rapids, they do not substitute for a touring kayak. These kayaks are the easiest to learn to "eskimo roll".

3) PADDLING EFFORT:
Are you willing to paddle hard? How far are you likely to paddle and under what conditions? How important to you is the performance and safety of the design? Apart from the effort involved in staying upright (see above), paddling also involves effort to move forwards (greatly affected by less obvious aspects of the design). Once again keep in mind what you want from the kayak.

Before deciding which kayak to buy you should assess
a) what is the kayaks cruising speed under average conditions,
b) is the kayak balanced, and
c) do you have an overall preference in the seating design

a) Cruising speed:
The speed of a kayak is obviously important to those wanting to race. It should also be important to anyone who might take their kayak into conditions where there is a risk of being tired (longer trips), or a risk of being up against weather conditions, particularly wind, that makes the paddling hard going. In these cases, a faster kayak is a safer kayak. A longer kayak should have a higher speed, but the difference between a bad or good hull design is significantly more important. The potential speed of a kayak also relates directly to less effort needed to paddle a given distance, and this is where "faster" kayaks have an advantage for the average paddler.

b) Balance:
The position of the paddler in the kayak, and the sideways resistance of the kayak, fore and aft of the paddler, needs to be balanced. This gives the paddler the best control of direction. This is particularly important in windy conditions. A common fault of kayak design is that the kayak prefers to face a certain direction when in the wind, making it very difficult for the paddler to choose where to go. This results in the paddler putting more effort into trying to turn the kayak instead of into going forward. If for example most of the sideways resistance to the wind is towards the bow (in front of the paddler), the stern will be pushed away from the wind and the kayak will face into the wind. If most of the sideways resistance is behind the paddler, the bow of the kayak will be pushed by the wind, and the kayak will face away from the wind. A rudder automatically increases the resistance to the rear of the kayak, making the most common design problem a kayak that faces downwind. This sideways resistance also changes as the speed of the kayak increases, and when the kayak faces into the wind or downwind. It is very dangerous when the wind is blowing offshore and you are paddling a kayak that lee-cocks (turns away from the wind). Trying the kayak in windy conditions, or reading up a review of the kayak's performance, or speaking to people who paddle the kayak regularly is advisable, before deciding to purchase.

Designers often try and rectify bad designs by moving the paddler weight further back allowing the bow to ride over swells and waves. This in return causes more drag of the stern of the kayak and can produce a kayak that will lee-cock. The Kaskazi Pelican was designed to weather-cock (turn into the wind) with the rudder pulled up and be neutral when paddled with the rudder down. Most of the kayaks currently on the market will lee-cock.

c) Comfort
The longer you intend to paddle at any given time, the more important it is to be comfortable. The seat, and back support offered by the kayak should be checked. Sit in the kayak in the shop to try this out.
Recreational kayaks often have a shallow sit-on-top seat, which means very little back support. On the plus side, a sit-on-top is easier to learn to use, as there is no cockpit that can fill with water, and no sprayskirt. A sit-on-top is beneficial if you want to easily get on or off the kayak (such as for diving or snorkeling). The down side is that there is exposure to the elements and a greater risk of hypothermia and excessive exposure to the sun. Greater care needs to be taken in the choice of paddling clothes.

Sit-on or sit-in debate:
Sit-on-top kayaks (Perception; Swing, Synchro, Prism and Torrent, Necky; Dolphin, etc.) are casual recreational kayaks where the capabiities to handle adverse conditions were traded for extra width and excellent stability, which is of paramount importance to the casual paddler.
Sit-in-side kayaks (Kaskazi; Darter, Perception; Spectrum and Sea Lion, Prijon; Seayak, Necky; Looksha, etc.) are generally much more comfortable as they come with a full seat, and therefore tend to be the choice for touring and expedition kayaking. These kayaks have less initial stability than the recreational kayaks (still adequate), yet still have a fair bit of secondary stability, but more importantly, have the capabilities to handle more adverse conditions. The paddler needs to learn to wet-exit a kayak if he expects to paddle in conditions where falling out is possible. This skill, plus the skill of re-entering the kayak, can generally be covered in a one-day basic proficiency course plus a little practice. The paddler of a sit-inside kayak is protected from cold water, and wind, which is also a comfort factor. Wind chill can reduce the temperature experienced by up to 10 degrees from the ambient temperature.

Some kayaks are difficult to categorise. Some sit-in-sides have a capsule type cockpit (Kaskazi double and Seebee), which limits water entry and makes it easy to get the water out. Some sit-on-tops have features that make them more comfortable (back rests, higher sides or deeper seats - such as the Kaskazi Pelican, which has the performance of a sea kayak, and the stability of a recreational kayak). As kayaks have standardized seats (but people are not standardized as to the shape of their behinds) it is important for you to actually sit in the kayak and try it out. Some cockpits have more or less space, either too big for the smaller paddler or too tight and uncomfortable for the larger paddler. Some kayaks are not designed to carry larger paddlers (Perception Scimitar), while others will only perform well with a heavy paddler and extra gear on board (Explorer).

Singles versus double:
There is always safety in numbers. Two kayaks or two paddlers on the water are always safer than one. Singles give independence and more packing space than a double. Singles can lead to stress on the water if the one partner is always faster than the other, in which case the double has the advantage.
Doubles are fun and fast (longer length), require 2 people in the kayak (or some weight in the front), and require only one to paddle at a time (the other can take a break, take a photograph, do bird watching, etc.). You can never leave your partner behind and you can match experience with inexperience. BUT is your partner always available? Doubles are more difficult to transport, are heavier than a single, more difficult to store (proper sea kayak doubles are mostly over 6 m long). One double is also cheaper than 2 comparable single kayaks.

Technical aspects
Understanding the complex technical aspects of kayak design is not necessary to enjoy kayaking. It is helpful in providing you with insight into hull designs and eventually choosing a kayak or even designing your own kayak. The following represents the fundamental characteristics of boat handling:

• Speed - a function of length, width, and hull shape
• Tracking - ability of the boat to go straight.
• Maneuverability - ability of the boat to turn easily
• Initial or primary stability - effort it takes to lean the boat off of an upright position
• Final or secondary stability - effort it takes to tip the boat over

Looking at the fundamentals it is immediately clear that it would be nearly impossible to have one kayak with all the positive attributes - there would have to be tradeoffs and these generally are:

• Tracking vs. Maneuverability
• Initial vs. Final Stability
• Speed vs. Stability

Waterline Length vs. Overall Length
The Prijon Seayak is nearly 25 cm longer than the Kaskazi Pelican, yet they have the same waterline length and also a nearly identical waterline beam. It is the waterline length that is important in proving a kayak with speed capabilities. Overhangs often soften the kayaks progress into swells and waves. Skeg-like bow and stern sections will improve the kayaks ability to track, may provide for a drier ride, but will further reduce the effective waterline that is crucial in providing the top speed capabilities of the kayak.

Speed and resistance
Resistance of a kayak consists of volumetric wave making resistance and surface based friction resistance. At low speeds friction based resistance dominates, while at higher speeds volumetric wave making resistance dominates. The fullness of a kayak (at waterline) plays a beneficial role in reducing volumetric resistance at higher speeds. This fullness of a kayak as described by the prismatic coefficient plays a important role in especially high performance kayaks.

General considerations
Designers will spend years designing and perfecting a kayak with low surface drag, reasonable wave making drag and great handling. The kayak builder and paddler can then negate all of this by the choice of materials, addition of a rudder, thickness and entry and exit points in the water, additional weight, condition of the hull with regard to scratches and dents and the incorrect trim of the kayak.
All other things being equal, the longer the waterline length, the faster the boat. When a boat travels through the water, it must part the water at the bow and that water must return smoothly at the stern for efficient movement. A longer waterline length generally makes this transition smoother. In a boat with an upturned bow and/or stern, the overall length is often far greater than the waterline length. If we take a very simplistic look at speed then we can say that the effective top speed of any non-planing displacement watercraft is a function of the waterline length and can be calculated (for a 4.8 meter kayak this is about 9.5 kph). Try to go any faster and the boat is being forced to climb out of the water on its own bow wave. The energy required becomes very large, until the boat lifts enough to plane, which is generally beyond the ability of the average paddler on flat water, but possible in the surf and very steep ocean swells.
The hull length is not the only criteria for speed, and a host of hull parameters (including displacement, waterline length, effective waterline length, draft, wetted surface, prismatic coefficient, centre of buoyancy, angle of entry, fineness of entry and exit, waterline beam, and the midsection coefficient) play not only a role in the effort needed to paddle a kayak, but also in the as important seaworthiness of the kayak.

Plastic kayaks scratch and ding easily and each scratch and ripple adds to the surface resistance (up to double for an old scratched kayak versus a new one). A rudder adds to the resistance and a vibrating and loose rudder even more (up to 5% increase in total resistance)

At low speeds (up to about 5 km/h) most available kayaks show similar resistance figures and the effort needed to paddle is relatively low, and obtainable by the vast majority of paddlers. Above these speeds the effort required increases and the difference between the shorter and longer kayaks becomes more apparent. Less powerful paddlers can find it easier to rather paddle shorter kayaks at slow cruising speeds than longer and potentially faster kayaks. The advantages of longer kayaks are only really apparent at higher speeds (8 km/h and much more). These speeds are not practically obtainable by the shorter kayaks.

Hull Cross Section
Cross sections from the centre of a kayak are usually what you will see in a manufacturer's catalog. Hull cross sections will show to what degree a hull is rounded, flat, or V-shaped. Seaworthy kayak hulls will fall between rounded and V. A V hull will provide better tracking than a flat hull. A round hull will offer the least stability, but often the lowest wetted surface.

Flare
A boat has flare when the topside (area of kayak from waterline to deck) inclines outward. Flare is usually added at the bow for lift over swells and waves, and to provide drier rides, or along the sides for increased stability. Excessive flare around the mid-section creates an unnecessary wide kayak, and excessive flare at the bow can provide for a very wet ride in choppy and windy conditions. Moderate flare in the mid section of a kayak will often provide secondary stability.

Rocker
Rocker denotes the curve of the hull from fore to aft. The more rockered a hull, the greater its maneuverability. Increased rocker shortens the waterline length, and thus reduces efficiency and also directional stability, or tracking. A moderate V-hull combined with a fare bit of rocker can provide the best of both worlds.
To build a very fast kayak eliminate the rocker, keep the width down, add a rounded hull for reduced wetted surface, remove any overhangs for a plumb bow and stern (a longer waterline length), increase the prismatic coefficient to 0.65 or more, and then give it to your worst enemy to paddle. Although you will have a very fast and probably slightly unstable kayak on flat water, it will have a kayak with too many bad habits for open ocean paddling.

Stability
Most sea kayaks are designed to attract newcomers to the sport and favour relatively flat-bottomed shapes, which feel "safe" to beginners. However, these designs have excellent initial stability and often poor secondary stability and can suddenly capsize when leaned beyond a certain point. Experienced kayakers prefer a design which emphasizes secondary stability over initial stability. Novice kayakers not only favour initial stability but will often "fall" out of a kayak before the secondary stability becomes apparent. The width of a kayak is not always a good indicator of stability. A moderate V bottom with soft chines feels a bit tippy at first, but gains stability when leaned and feels predictable even with the coaming in the water.

Seat height
Seat height is another very significant factor in stability. High, comfortable seats may feel great when the kayak is sitting in the dealer's showroom but can raise the center of gravity enough to become tippy and outright dangerous at sea. Even a difference of 2 cm can cause a radical change in stability. The closer you can get your posterior to the bottom of the kayak, the better.

A polyethylene kayak is rotationally molded or blow molded. Both prosesses deliver good comparable kayaks. In a rotational molding process, granules of virgin plastic powder are slowly introduced to a constantly rotating heated mold. As the plastic granules melt, they form to the insides of the mold, eventually taking on the shape of the kayak. Some manufacturers have computer controlled molding processes, which slows the rotation down at certain points, allowing for a thicker, sturdier buildup of material at certain points of the hull.
In a blow-molded process, a tube of melted plastic is dangled down into a sealed mold, and then blasted against the sides of the mold by an injection of high pressure air. Prijon Kayaks of Germany is the chief proponent of blow molding technology - most other plastic kayaks are of the roto-molded variety.
Poly kayaks offer first-time buyers a number of advantages. They're inexpensive (except in South Africa), extremely durable and extremely low maintenance. On the downside, they are heavier and flex more than most fiberglass and Kevlar composite boats, which is why serious touring kayakers are committed to fiberglass or Kevlar composite layups.

Construction techniques
Construction of fibreglass kayak and poly kayaks all start from an original kayak - called the plug. This is often built out of foam or wood, tested, modified, re-tested again and again until it is right. This plug is then faired, smoothed and perfected as far as possible as any imperfections in this kayak will now be in all future kayaks built.

Once the builder is satisfied a mould is then built around this kayak. For fibreglass kayaks this mould is also fibreglass, but many times thicker than a kayak would be, for polyethelene kayaks this mould is often milled from a block of aluminium at huge costs. Once these mould are built the kayaks can now be manufactured from them.

Not too many years ago kayaks were mostly derived from previous models- adaptations were done to an existing model and mould was made from this kayak after testing proved it to be reasonable. With the latest computer design packages and optimisation packages it is possible to design a kayak and be able to know with reasonable accuracy how the kayak will perform.

When buying a kayak it is important to ask a few questions about construction and where the design originated:

Plastic kayaks
Plastic sea kayaks are not manufactured in South Africa (March 2000) and are imported from abroad at great cost. Being imported and having a hefty price tag does not guarantee a good product. In the rest of the world plastic kayaks are considered entry level and are cheaper. Because we import them into SA, they cost substantially more and we often think of them as superior. Have a good look at the kayaks; some are old designs, some are very user specific, some are brilliant kayaks.

Once again - ask questions!

• Is it from a reputable international supplier with a good track record?
• How long has the model been on the market?
• Is this because it is a good kayak?
• Or because the manufacturer does not have the capability to renew models?

As one of the major world manufacturers put it "no-one has ever made a success from copying our plastic kayaks, and it has been tried all around the world." Not all manufacturers are so understanding and would pursue breaches of copyright and design. Plastic kayaks often don't translate well into fibreglass models, and you would be better off choosing a design and manufacturer who understands this and will be around for a few years.

A polyethylene kayak is rotationally molded or blow molded. Both processes deliver good comparable kayaks. In a rotational molding process, granules of virgin plastic powder are slowly introduced to a constantly rotating heated mold. As the plastic granules melt, they form to the insides of the mold, eventually taking on the shape of the kayak. Some manufacturers have computer controlled molding processes, which slows the rotation down at certain points, allowing for a thicker, sturdier buildup of material at certain points of the hull.
In a blow-molded process, a tube of melted plastic is dangled down into a sealed mold, and then blasted against the sides of the mold by an injection of high pressure air. Prijon Kayaks of Germany is the chief proponent of blow molding technology - most other plastic kayaks are of the roto-molded variety.
Poly kayaks offer first-time buyers a number of advantages. They're inexpensive (except in South Africa), extremely durable and extremely low maintenance. On the downside, they are heavier and flex more than most fiberglass and Kevlar composite boats, which is why serious touring kayakers are committed to fiberglass or Kevlar composite layups.

Fibreglass kayaks
Generally fibreglass kayaks are manufactured in South Africa and once again you would have to sort the good and the bad.

• Ask where it originated from who designed it if it was not imported (if it was imported be prepared to pay well over R10 000)?
• turn the kayak over and look for any tell tale ripples in the hull (and also the deck) indicating the kayak was either moulded from a poorly built plug (and probably poor design) or more probably from a plastic kayak?
• If you see one or more lines across the hull (generally just behind the seat area) it is either from the bulkhead on the original plastic kayak it was copied from, or an original kayak that was lengthened?
• if the bow and stern (entry and exits) of the kayak is thick and flat it was most probably copied from a plastic kayak - fibreglass allows for fine entries while the inherent lack of strength from plastic requires thicker ends.
• ask about materials - if it is plain old chopstrand mat, go elsewhere or be happy with a heavy boat more prone to breakage but at a bargain price
• ask as many technical questions as you can - if you can't get any answers, go elsewhere or take a chance

Kayaks that are lengthened manually as opposed to taking the design back to the computer and redesigned to the new lengths and widths are often not too successful. Changing the mid section of a kayak affects waterflow at the ends as well, and often require an increase (or occasionally a decrease) in volume towards the ends of the kayak.

In fibreglass construction, a female mold is sprayed with a coloured gelcoat or a gelcoat is applied by hand, and then layers of fiberglass, carbon or Kevlar cloth are wetted with resin and pressed into the mold. When top and bottom halves of the boat are both dry, they're fitted together using fiberglass sealing seam, outfitted with seats, rudders, deck lacing, etc. and ready to be paddled.

In general, good quality composite boats are more responsive, quicker to accelerate, and feel a bit faster than plastic boats. If you've never tried a good quality fiberglass kayak, you should at least try one before committing to plastic. They are less expensive than the polyethelene kayaks (in South Africa where fibreglass work is very affordable, as opposed to the rest of the world where plastic kayaks are cheaper and often considered entry level), and they will reward you with exceptional performance. You're probably only going to buy one kayak in your life - you might as well get the best one you can!

Wooden Kayaks
Wooden kayaks made of plywood (stitch and glue method) or wood strip, are gaining in popularity again. Plywood kayaks can be made in your garage in around 60 hours of work. These kayaks are rigid and lightweight and in many ways comparable to carbon and kevlar in strength and stiffness. They are relatively cheap to make yet expensive to buy (they require many hours to build).

It is not always easy to spot a good or bad kayak in a shop, unless you have expertise in design. The best is to request a demo of the performance, ask as many questions as possible, and obviously speak to people who have paddled a range of kayaks. Beware of paddlers who have only ever paddled one kayak and have no way of comparing performance, comfort and safety. All the characteristics of a kayak, both good and bad, are not always easily recognisable and appreciated by novice paddlers.

When trying out a kayak check if the stern of the kayak sucks down while paddling (this will significantly increase the effort), look at the bow of the kayak to see if it pushes a wave of water forward or slices through it. In order to do this you will need to watch someone else paddle the kayak.

• look carefully at the waterflow around the kayak
• how well does the kayak respond to paddling effort?
• will it go faster the harder you paddle?
• where is that point where no matter how hard you paddle, the kayak will not respond with more speed?
• how does the kayak handle in beam winds (wind from the side) and chop?
• how does it feel in following seas (wind and swells from behind)?
• how well does the kayak respond to body and rudder input to turn quickly?
• how does the stability feel as you lean the kayak?
• how dry is the kayak in choppy conditions?
• how comfortable do you feel?