[Kayak Design Software
Virginie Fayad
The hull is the frame or main body of a ship or boat. For a kayak, most of what you see is the hull. And the shape of the hull can have a big impact on the stability, speed, maneuverability, and trackability of your yak.
If your primary goal in kayaking is to get from point A to point B as quickly as possible (a straight line, amirite?), then you might be interested in a v-shaped hull. The v-shape provides excellent tracking. With more of the hull pressed in by the water from the v-shape, it will maintain a straighter line. The same shape also cuts through the water cleanly to increase speed. Speaking of cutting, this shape can also withstand rougher waters because of its knife-likeness. However, a v-shape is likely to be more unstable than the other designs in calm water and at slower speeds.
If there is a clear delineation or edge where the bottom meets the side of the hull, you are looking at a hard chine. Creating this sharp edge allows the kayak to perform carving turns. But they are also likely to catch on debris and flip an unwary paddler.
The soft chine lacks the pronounced edge of the hard chine and allows the side to meld seamlessly into the bottom of the hull. The soft chine is considered better for beginners as they are less likely to flip, spin, or misdirect.
This last type is often mistaken for a soft chine because it can be difficult to discern at first glance. The multiple chine attempts to get the best of both worlds by providing a bit of an edge for carving turns but a smooth side for less catching and flipping.
Another kayak design feature to consider is the rocker. It might help to consider a rocking chair (or a banana). Is your kayak hull (from bow to stern) greatly curved or gently curved? If the edges of your kayak curve up and out of the water at the ends, you probably have a large (more) rocker. This design means that the kayak will bump against the waves less, which will decrease resistance and improve maneuverability. A gentler (less) rocker will allow more water contact which will improve tracking and speed.
Try our kayak customizer. You can choose between different hull, line, bungy and hatch colours to make your own striking appearance on water. You simply start by choosing the kayak you want to design.
DesignKayaks is a Danish sea kayak brand: Stunning colors, exceptional performance. Unmatched value for money for you and your customers. Our model range consists of three models designed to meet different demands. They apply to everyone from new paddlers, exercise and touring paddlers all the way to instructors, technique and surf aficionados.
Passion seeps through every step of the process when we make our sea kayaks. Our factory is located in the city of George in South Africa and with our modern roto moulding techniques we produce our high quality 3-layer PE sea kayaks in a well engineered and computer controlled environment.
Welcome, paddler! Whether you're looking to chew threw the miles on a months-long kayaking expedition, play in the swell to test your skills, or just spend a little time on the lake, you'll be in good hands in a Current Designs kayak. With over 40 years of history, a CD kayak will keep you safe, comfortable, and inspired no matter where you find your next adventure taking you. A work of art; made for life.
The successful design of any boat is a subtle blend of art and science. While there is a lot of room for personal preference and choice, there is also much that is constrained by the immutable laws of physics. The artistic choices are in determining the desired performance and then shaping the boat such that it interacts with the hard-and-fast rules of nature to achieve those goals.
While there are obvious differences between a super-tanker crossing the Atlantic and a kayak bobbing on a bay, the water and gravity effecting the two boats are exactly the same. The science developed for large ships is precisely the same as that which relates to small boats like a kayak or row boat. The difference is the design goals of the kayak designer vs those of the ship designer. While a tanker designer needs to worry about carrying a heavy load across an ocean and into defined spaces like the Panama canal, a small boat designer may want a kayak that carves down a wave or is stable for fishing.
The reason a tanker looks different from a kayak is not due to some difference in the way physics applies to the two boats, but the fact that their intended purposes are different. The task of designing any boat should first start with determining that intended purpose. The same applies when choosing an existing design for your own use.
Chapter One Life in Illorsuit; Chapter Two Subsistence activities; Chapter Three Ikerasak Village and Uummannaq Town; Chapter Four Building the Kayaks; Chapter Five Variations in Kayak Design; Chapter Six: Skinning the Kayaks; Chapter Seven The Hunting Equipment; Chapter Eight The Hunting Trip to Umiamako; Chapter Nine The Kayak Race in the Village Bay; Chapter Ten The Rolling Competition; Chapter Eleven Re-encounters with the Kayak
At all the villages I stayed in or visited, also at the Umiamako hunting camp, and in Uummannaq town, all the kayaks I saw and in many cases measured did have the same distinctive design. They all had the noticeable simple, positive sheer to the gunwales, the very low fore deck, and the slightly upturned stern. There was one way in which some of them were significantly different from all the others, as I spell out below [this had to do with their cross-sectional shape], but the basic design was the same wherever I went. In his KoG, Harvey Golden describes and analyses 13 distinct types of Greenland kayak design, spanning the 400 year period, 1600 to 2000, with beautiful scale drawings of the 104 kayaks he describes. The Uummannaq Bay kayaks that I saw in 1959 were examples of his Type VI.
One way in which the Greenland kayak designs varied from place to place had to do with the curvature of their gunwales. [The gunwales are the longitudinal boards that form the edge between the deck and the sides of a kayak.] Petersen describes two ways of shaping the gunwale strakes. One involves adjustments in the vertical depth of these strakes, by cutting away portions of the wood and/or adding to the depth of the wood as shown in the sketch below.
Tobias posing with his harpoon during the hunting trip to Umiamako and me showing the use of the harpoon at Loch Lomond in the spring of 1960. These two photos show very nicely the curvature of the sheer line in Uummannaq Bay kayaks of 1959.
Sheer, the line of the deck from bow to stern, traditionally starts high at the bow, dips amidships and then climbs back to the stern at a point lower than the bow. There is a reason for this. The bow is high because it must climb over waves. The midship area is low to allow access to the water by paddles or oars. The stern is then upswept to rise over following seas.
Boat design is a massive collection of compromises. Fish-form is fastest, but hard to handle without a rudder. (Have you ever seen a fish without a tail?) Symmetrical is easier to steer and slightly slower. Swede-form sacrifices a little more speed for a lot of directional stability.
The next consideration is the cross section of the hull. The theoretical best shape is round, like a log. This would have the least wetted surface and thus the least drag. It would also be unstable (like a single scull rowing boat) and require constant balancing with the paddle (or oars.)
Most Australian kayak designers have simply flattened the round shape on the bottom to gain the necessary stability. Many American designers are now tending to favour hard chines, a return to the original Inuit shape which was dictated by strips of wood covered by seal skin. Hard chines increase the wetted surface marginally, but return a major dividend in terms of tracking. They also act like surfboard rails which help manoeuvrability in breaking waves.
There is still another hull characteristic to consider: the keel line from bow to stern. For many years, racing kayakers and canoeists thought that a flat run was the most efficient. Now the trend is for the bow and stern to be raised in the form of rocker. Rocker yields less wetted surface and thus reduces drag. Pronounced rocker also allows the bow to lift more easily over breaking waves. However, the main advantage for sea kayakers is the additional ease of turning.
Paddling downwind is where tracking ability is most important. In general, boats will lay broadside to the wind when not under sail, paddle or power. If the paddler wants to head further off the wind, the kayak will try to return to this position, or sometimes round up even higher.
If the kayak is Swede-form and the bow is high due to pronounced sheer, the kayak may actually lay naturally almost downwind which means that the paddler can use far fewer course-correcting sweep strokes and concentrate on forward progress.
The next consideration in kayak design is length. I tend to favour lengths in the vicinity of 16 feet. Many feel this is too short to carry enough supplies for overnight trips. I find it adequate. In addition very few kayakers actually take extended trips and pay a large penalty in weight and convenience for the mostly unused cargo capability when day paddling.
There is a commonly held belief that longer kayaks are faster. In theory, this is true. The effective top speed of any non-planing watercraft is a function of the waterline length and can be calculated in knots as 1.34 times the square root of the waterline length in feet. (For a 16 foot, 4.8 meter kayak, this is 5.36 knots or about 10 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. Not even the legendary Dave Winkworth is powerful enough to get a kayak to plane on flat water. Very narrow hulls, like those on a Hobie Cat, are exceptions to the equation, but still require more power than a paddler can muster to really get moving.
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