Features and Their Effects
There is much more to consider than bright colours and fancy attachments when buying a kayak. This page is a brief overview of some key design characteristics that you should be aware of before buying such as: the intended usage, the size of the paddler, the cargo capacity, tracking ability, stability, length, width, and material used in construction. When all these factors are considered, one can begin to understand the compromises involved in a design.
If you are new to paddling, the tendency is to choose a kayak that is larger and more accommodating (stable) than what you might like later, as the learning curve to enjoying a kayak is quite short. Take a course to get yourself pointed in the right direction. You will probably find that there is more to learn than you thought, but the sport of kayakng can be as easy or as difficult as you want to make it.
How is the kayak to be used? Will you be day paddling on small lakes or a quiet stream? Or do you want to be out on large rivers, lakes or bays with the possibility of wind and chop? Will you be fishing or using the kayak for photography, bird watching, etc.? Will you be the only person using the kayak? Will you be loading the kayak unto your vehicle by yourself?
The length of the waterline is "one" of the factors governing the potential speed of the kayak as this indicates the amount of water displanced and the wetted surface area. These directly affect increased friction or drag. The displacement speed of the kayak is approximately 1.34 times the square root of the waterline length. It should be noted that most paddlers only travel at about half or two thirds of displacement speed as it takes a lot of effort to get near the displacement speed that is theoretically possible.
Beam is the widest measurement of the kayak. Generally the wider a kayak is the more stable it will be but there is a price to pay for this increased width. As they become wider they will have more surface area in the water, which will increase surface drag and will require more work to paddle. There are practical limits on how wide or narrow a kayak can be. If the beam is very extreme or the paddler is short it is hard to reach over the kayak to paddle comfortably and if it is too narrow the kayak could be "tippy" or even hard to keep upright. Often kayaks you rent have a wide beam to make them safer for the paddler especially those with no or little experience. Paddling one of these all day can be very tiring.
Chine is the transition area where the bottom of the hull meets the side of the hull. There are two basic cross sectional shapes for kayaks with many variations possible in between. There are round shapes,(soft chined) and v-shaped shapes (hard chined.) Generally hard chined kayaks which have a well defined edge where the hull bottom meets the sides have more initial stability (feel less "tippy") when you are just sitting in them or paddling in quiet water. Soft chined kayaks, may feel more "tippy" when just resting in the kayak but when you are in water with some chop or wave action they will feel more stable because they have what is called higher secondary stability.
For more details on stability see the "Kayak Stability" link above.
Tracking and Rocker
Rocker is the amount the ends of the kayak are curved upward in relation to the centre of the hull. (Top photo has less rocker while bottom photo has more rocker.) A kayak with little or no rocker will track very well, but can be more difficult to turn. As the amount of rocker increases, kayaks become easier to turn, but may not track as well. In some kayaks the middle of the kayak is straight and just the ends curve up while in others the rocker is continuous. Thus kayaks with different intended usage will have different rocker styles. Some of these different options are difficult to evaluate on flat water and only become pronounced in wavy conditions. Rocker can also be increased by leaning the kayak over making it easier to turn the kayak as the ends come free of the water.
As kayaks are designed in a bewildering number of sizes, lengths, widths and shapes a useful measure when comparing them is to look at their total volume. Total volume is a fairly accurate indicator of a kayak's gear carrying capacity but how the volume is distributed can have quite an influence on the storage volume available. For instance, a kayak with fine ends and a high amount of volume in the cockpit area would have less storage capacity than a boat with a more equal volume distribution.
There are a variety of cockpit styles. Their dimensions and shapes are tailored to the purpose of each kayak and the comfort of the
paddler from the first-timer, to the expert.
Open Cockpit - These are very easy to get in and out of, and give a feeling of being almost completely free from the boat.
Recreational Cockpit - These are long enough (36 - 40 inches) so you can easily stand on the floor in front of the seat and simply sit down. They are un-restrictive and many new paddlers appreciate their roominess and versatility.
Touring Cockpit - Typical touring cockpits are somewhat small and allow the use of a spray skirt. They usually include built-in thigh braces on the cockpit rim to maximize control when edging and rolling. They range from 29" to 35" long, depending on the model.
Ocean Cockpit - These are much smaller than a touring cockpit. In some cases these are nearly round, giving a very snug fit. To get into this cockpit you slide in with both legs simultaneously. Ocean cockpits are very resistant to rough water and weather conditions. The drawback is that they limit some paddler's ability to get into the kayak, and make some people nervous about the ease of a wet exit.
A deeper hull will be roomier for paddlers with larger legs, and increases load carrying ability. It also improves secondary stability by having more volume to help support a paddler while the kayak is on edge. A shallower hull will be less effected by wind, but will carry less, and may be too shallow to comfortably fit some paddlers.
It is often said that paddlers "wear their kayaks." This is more than a figure of speech because the degree of control you exert
over your kayak as well as your paddling enjoyment depend largely on your body contact within it. As all people are different,
so each person will want a slightly different fit in their kayak. You should be able to lock yourself into your kayak with your feet,
knees/thighs and hips. For bracing and rolling it is important that you not slide around in the kayak but at the same time you are not crammed in
so tight that it is uncomfortable. As a minimum your kayak should have an adjustable backrest/brace and an adjustable foot brace.
Most kayaks can be custom outfitted, certainly when they are being made but also to a lesser extent after they are constructed. While it is possible to make a kayak tighter fitting after construction it is very difficult to make a fit larger. As such, the choice of your kayak should hinge first on the right body fit and the comfort it gives and second on your skill level or intended paddling style.
Material Used in Construction
I build wooden kayaks. There are a variety of other materials used in building kayaks such GRP (glass-reinforced-plastic), HDPE (High Density Poly-Ethylene), Rotomold (Rotationally Molded Plastic), carbon fiber and kevlar. Each has it's advantages and disadvantages but I am biased towards wood. To read more why wood is my preferred building material follow the "Cedar in Kayaks" link above.