Knowing and Understanding the Kayak

Introduction

When I was introduced to the world of kayaks, I came across numerous terms, which were unknown to me, such as primary stability, hull, rocker and other such jargon, related to “kayaks”. But I was most insistent to gather all the information related to this amazingly conformable and compact boat to understand them better. For this, I consulted countless text and written material, but the problem was that the things I came across, were not authentic, since no claim was made that the information is original nor I got any final say on this subject. Since I personally experienced a huge gap between my need for knowledge about kayaks and the availability of kayak information, so I actually felt the inadequacy faced by the kayak lovers like me. So here I am, with an intention to help novice and for that matter, the professional paddlers, since information never hurts anyone.

Structure

Basic construction of a kayak includes three components: hull, deck and cockpit. All the three parts are separately manufactured with some super-strong material like fiberglass and welded together, by a chemical process, to give you a lightweight boat called kayak.

kayak-structure-1

With more advancement in kayak technology, new materials such as Kevlar, Carbon and Polyethylene are now used to manufacture kayaks, making them sturdy and lightweight. Some of the models available, have internally enclosed cockpit-shaped cocoon, while others are open. Without a cocoon weight of the boat definitely reduces, but if overturned such a kayak will be immediately and fully flooded with water.

How the kayak or boat, is constructed and what projections are possible in the kayak, define its inherent qualities, which distinguish one kayak from another. The first set of features are associated with design and manufacturing represented by strength, buoyancy and water tightness. The qualities which are related to the projection are capability in ocean/sea, ease of maneuverability, resistance to drag and stability.

To get an ideal kayak (if that exists), you should take into account the type of activity you want to do with it and the place where the activity will be undertaken. For example: a simple recreational activity in lakes and reservoirs, small excursions in lazy rivers, long expeditions in coastal waters or in descents of rapids (whitewater), canoeing on sea/river waves. In addition to these some miscellaneous things like space for carrying luggage, Kayaking for capturing photographs, fishing, diving, etc. also drives the utility and worth of a kayak.

Getting a boat which meets all the desirable qualities is just impossible. You have to compromise on one feature to get some other advantage, which you cannot do without. So some of the opposing factors, which can be paired together are high stability vs high speed, great maneuverability will compete with boat’s ability to remain stable and upright and the initial stability (primary) will duel with the final stability (secondary). The best way to choose a boat is, to try it in various paddling conditions (calm, flow, turbulence, waves, wind, etc.), and observing its fundamental characteristics such as speed, tracking, handling, initial and final stability.

Types of kayaks

There are different types of kayaks, suitable to a particular purpose. In order to understand more about the boats, you must understand the following terms

how kayak works - make and design

  • Stern – back portion of the boat
  • Bow – front potion of the boat
  • Hull – Kayak bottom
  • Chine – curve between the sides of the kayak and its bottom
  • Rocker – portion of the curve between the stern and the bow that lies above the water surface
  • Flare – the lateral angle with respect to the hull

Sea or touring kayaks

sea and touring kayaks

The ocean or touring kayaks are long, stable and have huge space for anything you wish to carry along. The hulls are narrow, the Chines are stiff and broad, giving them a wide flare. Such structure of the Ocean Kayak, makes it less maneuverable, but very fast to be paddled in a straight line. These kayaks glide with each stroke, so they are speedier than the shorter sports types. They come in the versions of one seats and two seats with rudders to help in easy maneuvering. This kayak allow the paddler to sit inside the cockpit or sit atop – more like a canoe.

White water kayaks

White water kayak for you

White water kayaks are shorter in length and are slightly less stable, but are much more maneuverable. They are highly durable and built to face the extreme challenges of paddling in rapids. With a typical length of 2.5 meters and round hulls, they have softer chines and minimal flare. This helps in rapid maneuvering and scrolling, because the portion of the kayak which is in contact with water is very small. They also have a considerable rocker, which helps in reducing contact area with water. The paddler has to sit inside the cockpit, in this kind of kayak, to tame the kayak in rapids that too without a rudder.  These kayaks are also used in kayak-polo practice.

Surf Kayak

surf-kayaks

Surf kayaks are similar in shape and structure of white water kayaks. One big difference is the rocker, which is of the shape of a bow rocker.  The stern is flat, like a surfboard. Many surf kayaks are created with planks to maneuver it like fins.

Recreational kayak

Recreational kayaks, as the name suggests, are the kayaks that are used for expeditions on water surface and recreational activities for short durations. This type of kayak is characterized by sit-on-top rotational molded plastic seats, and are known to be the best-selling kayaks around the globe. Since they are the most popular, so paddlers want to know more about these high-utility kayaks, I have devoted an entire section to them and other most appreciated kayak- the fishing kayaks. This will make a good part of our discussion, to be followed later.

Materials of construction

Reliability, durability and performance of a kayak is defined by the material used for its construction. It also has a great impact on the price of a kayak. The kayaks can be made of different materials. Surf kayaking are mostly made from fiberglass – the models for tubing are often made of plastic. This is because the traditional plastic does not provide stiffness and low weight of fiberglass. The ocean kayaks are generally (in Brazil) made of fiber, but may be made from wood or plastic. But at exterior, the ocean kayaks are mostly made up of plastic. Some of the most modern rapids kayaks are made of Kevlar, a lighter and more resistant material.

Considering various materials for making its body, Plastic is the cheapest, and also the heaviest. Fiberglass is 20% lighter than plastic, but cost of a fiberglass kayak increases by 20%.  Kevlar is the lightest of all materials and also the toughest, but it costs twice as compared to the fiberglass. Weight is something that must be considered because, unfortunately, you spend more time out of the kayak than in it. That means portability of the kayak, its installation, carrying it from the garage or storeroom rack to the roof of your car are other important factors to be considered.

You can also opt for a traditional wooden kayak, which displays some true workmanship and look like a piece of art rather than a recreational gear. Another choice could be an inflatable kayak, which is quite lightweight and durable opposite to your expectations.

In the next section, I will discuss the various issues about stability and types of Kayaks.

 

What is stability?

Kayak stability rules

The definition of stability is quite clear to most of the people. A boat that does not rock or tip back and forth in water is stable, and if it rocks, it is unstable. Although, it looks very simple and logical according to the definition, but for different paddlers rowing the same kayak, may have different opinions on its stability. So, to understand the kayak functioning, understanding the meaning of a kayak to be “stable”, is very important. Dictionary defines stability as “the balance is not Detroit with a slight variation in conditions”. Considering the function of a kayak, if a kayak returns to the upright position after a slight variation in its position or if the paddler falls into the water, it is said to be “stable”.

Initial stability versus secondary stability

LOA – total length of the kayak.

LOA - total length of the kayak

GOOD – full width of the kayak.

full width of the kayak

Now let’s talk more about stability, for that matter, primary stability and secondary stability for a kayak. Kayaks with BOA (see image above) or wide BOA is always more stable than kayaks with narrow BOA.  Good, right? Well, no, not always. It depends on what kind of stability we are referring to. When we say that a broad kayak is more stable than a narrow kayak, we are actually referring to the “initial stability” and the expectation that such a kayak will not overturn, when paddler is rowing, but this is true only in calm and even waters. Kayaks, which are 70-80 cm wide, must have a great initial stability, so that with a little care and good balance, paddler should be able to climb in it and get comfortably seated for his adventurous getaway.

And that is precisely the reason that many novice paddlers feel safer in kayaks, which are wider. But it is not true that a large kayak is always safe and more stable than a narrow kayak. Under certain conditions, the initial stability can actually become an obstacle. When paddling in ripples with side wind, surf zone or poached sea, it is very likely that a large kayak overturns more easily than a narrow kayak. Why? Because the characteristics that give an excellent initial stability to the kayak, specifically, its widest BOA feature, also affects its performance in waves. Wide kayaks, always give a good initial stability, but when you incline them, beyond its center of gravity, they tend to trip and overturn. That’s because they do not have good “secondary stability”

“Secondary stability” refers to the capability of kayak to return to its stable position, after it is tilted sideways (as when a wave hits the side). Generally, a narrow kayak has better secondary stability, even if its initial stability is not good. Why? Because you can keep the torso erect, with almost no sloping sides and a narrow kayak can incline to match the slope of a coming wave, and then lets it pass over, without causing any harm to the kayak, or the rower. With a narrow width, the kayak is less affected by the wave, so the wave is not at all fatal and no roll over will be observed. To illustrate the difference between primary and secondary stability, this analogy would make the things crystal clear to you: Imagine two chairs, one chair is with four legs (wide kayak) and the other one is the rocking chair (narrow kayak). You will feel more comfortable and stable to sit on the four legged chair, since it does not move. But sitting on the rocking chair, you will feel unstable, since it moves back and forth. If, the four legged chair you are sitting on, is pushed back, surely you will fall flat on its back. But when the rocking chair on which you are sitting, is pushed back, how would you feel now? You will enjoy the push and request to push it again. So, same principle in works in kayaks too.

Kayak Largo

kayak-largo

Kayak Narrnow

kayak-narrow

Now to look upon other features of kayaks, let’s review some points of initial article, so that we can understand our boats, in a better way.

Chine

The point where the kayak bottom ends and the sides of the kayak, begins is called a chine (corner).

kayak front view

There are 2 types:

 

  • Soft Chine: This has a round or fillet shape, which provides an excellent secondary stability. The round shape also increases its speed, because it decreases the drag of kayak when paddling in water. “Multi-chine” is a type of soft chine.
  • Hard Chine: Its shape is clearly steeper, forming clean angles, increases control and initial stability. The hard chine is a great help, when a wave hits the kayak or the paddler decides to take a turn.

kayak chine

Waterline

BWL LWL Waterline

The waterline and online mapping showing, exactly how far the kayak hull is submerged under water level.

Side 

Side of a kayak is the part that extends from the waterline to the deck, and the sides influence the stability and the ability to maneuver the kayak. The types of side are:

  • Flare (facing away or open): this is the angle that is formed between the sides and the hull of a kayak where both are facing out or are opened.  More the sides are facing out, the greater is the stability, because most of the hull is below the water surface. Kayaks with flare sides have increased stability, but they are quite difficult to maneuver.
  • Tumblehome (facing outwards and inwards): when the side is facing out and then curves back towards inner side of the kayak. This creates a narrow platform that facilitates rowing, however, still offers good stability.
  • Straight: This form is a combination of  Flare and Tumblehome.

water line side

Hooves (Hull)

Body of a kayak is called Hull and is another determining factor for kayak’s behavior in water.

  • Rounded hulls (rounded hulls): It poses least resistance in water and can attain very good speed.
  • V hulls (hulls V): it offers less initial stability, but a better secondary stability and thus has a better straight motion.
  • Flat-bottom hulls (flat-bottom hulls): it gives a very good initial stability, but only on calm and even water surfaces but do not have good secondary stability.

kayak hulls

SOT  KAYAKS

California Hull

The California hull is a hull shape used exclusively in SOT kayak which combines the flat shell elements and a round hull. This is  the hull that gave popularity to kayaks as Ocean Kayaks. This combination provides a good tracking performance, speed (rounded central keel), increased stability (hull plan) and good performance in rough water (aquaplaning). The hooves of California kayaks can be combined with soft chines or hard chines.

california-hulls

Flare Sponsons

The sponsons flare, is a hydrodynamic feature used in the design of the kayak hulls, to increase stability when the kayak is tilted. Typically, the sponsons are characterized by being above the waterline and serve as stabilizers. This increases the width of the kayak, impairing the secondary stability by a small value. When the kayak is in motion and balanced, the sponsons are out of the waterline, decreasing the width and hence improved speed and glide. They can also deflect the water spray towards the deck.