Kayak study - GreenlandPaddle.com
spacer
spacer search

GreenlandPaddle.com
- Carved by hand

Search
spacer
header header
English version
Greenland Paddles
Greenland Gear
GreenlandPaddle.com
Greenland Antique
Order
Produkter & info
GreenlandPaddle.com
Grønlandske årer
Kastetræ & Harpun
Tuilik
Akuilisaq & Avataq
PaddleRoll
Grønlandica
Design filosofi
GreenlandPaddle Info
Qajaq ressourcer
Paddle technique
Photos
Ressourcer
Nyheder
Bøger og publikationer
Køb
 
GreenlandPaddle.com arrow Qajaq ressourcer

Kayak study

Image Greenland Rolling Throughout Recorded History

by Martin Nissen


THE KAYAK - A Study in Typology and Cultural History

by Jarmo Kankaanpää


Image The Women Kayakers of Greenland [PDF]

by Martin Nissen


Image H.C.Petersen - An Invaluable Admirer of the Greenland Kayak [PDF]

by Martin Nissen


Grønlandske skindkajakker i Nordeuropa

by Martin Nissen



Preserved Greenland Skin Kayaks of the World [PDF]

by Martin Nissen


Innovation or Hyperbole?

by John Winters

What would you do to improve the design of kayaks? More importantly, what can you think of that would have a dramatic (or at least noticeable) effect on kayak performance – an effect you could legitimately call an innovation?

Excluding technology that allows stronger and lighter boats and the paddling gadgets we seem to love, advances in hull design (although they seem obvious to those who write advertising copy) have had so dramatic an impact. In some cases, unique hull shapes have had negative results. In most cases, so-called revolutionary designs amount to nothing more than incremental development. Nevertheless, some developments in kayak design have altered the face of sea kayaking and I will address those later. For now it will pay to investigate some aspects of design development.

To illustrate why hull design advances don’t appear every day let me relate a story.

A number of years back Eugene Arima asked me to analyze a wide range of native craft. The study encompassed hydrostatics, stability and performance – not unlike the studies designers do of competitor’s boats to see how a new design stacks up.

As I analyzed the boats unmistakable patterns emerged and an unexpected uniformity existed. This surprised me given the time and distance separating the builders. Was it possible that, given a lightweight boat and pointed ends, designing a good boat came naturally and didn’t require any knowledge of fluid dynamics? The virtues of simplicity and purity of form appeared to take precedence over the latest fad or tortured shape promoted by specious and hyperbolic advertising. The idea had a fascinating prospect.

To test the theory I "designed" a kayak without resorting to any hydrodynamic theory. To this end I established rough parameters of overall length, beam, and depth. Then I defined an amidships section by more or less randomly picking a point for the chine. Using these points I drew curves to define basic hull shape. Next I added two stations dividing the hull roughly into quarters. I used these to provide enough room for my feet and increase the deck area aft for gear. This time I picked chine points to provide flare similar to the centre section and to avoid forcing the wood into an "unnatural" curvature. Allowing the chine to take on a similar curve to the sheer defined the amount of overhang; influenced the amount of rocker, and, to some degree, the shape of the stems. I tweaked the final stem curvature to suit my aesthetic preference.

The lines of the completed boat are shown in Figure 1 and bear more than a passing resemblance to native craft.

Granted that my training and my familiarity with traditional boats certainly influenced me in choosing my chine points. Nevertheless, an Inuit builder would have drawn upon his experience as well and I carefully avoided applying any hydrodynamic knowledge in the design. The only definitive guidelines came from the arbitrarily set dimensions, the size of my feet, the width of my behind, and what seemed like a reasonable deck area for carrying articles aft of the cockpit. The hydrostatic analysis provided the moment of truth. Were the numbers "good" and what would they tell me about my kayak?

Here they are in abbreviated form.

Length 17.0’ Waterline Length 15.09’ Beam 1.58’ Waterline Beam 1.36’ Prismatic coefficient 0.52 Block coefficient 0.40 Displacement 200 pounds Longitudinal Center of Buoyancy 49.5% Wetted surface 18.76 Square feet

In every category the numbers approach the average for traditional Greenland style kayaks. More importantly they do not deviate much from modern practice for good performance. In short, the boat has all the indications of being a good kayak in spite of myself. It seems like, to create a "bad" boat I would have to work at it.

Clearly this reveals that any new design must start from a high level. Any further improvements must become increasingly difficult as one gets closer and closer to the perceived ultimate. We can find a good example of how difficult improvement becomes from GODZILLA, a program developed by Leo Lazauskas of the University of Adelaide. GODZILLA starts with a "seed" shape and then modifies it incrementally to develop a boat with less resistance. It will do as many iterations as the user asks but after about 20,000 or so the improvements, if any, grow extremely small. Interestingly one can use a wide variety of shapes as a seed and get different shapes that have similar resistance.

Many manufacturers claim that their boats unique features that produce improved performance. For example, one claimed that their bow shapes maintain laminar flow longer thus reducing resistance. They don’t say longer than what but one must assume longer than competitors. This would truly qualify as an innovation if they could back it up. Examination of their hull shapes reveals nothing

special so we can justify some scepticism about the claim. Another builder claimed wonderful things for its transom stern. Transoms are nothing new to naval architecture so we have lots of information about what works, what doesn’t work and why. Evaluation of the boat using a performance prediction program revealed that the transom most likely did more harm than good at cruising speeds and probably didn’t help at higher speeds. Kayak builders often overstate the merits of chines as well but no claim has more than anecdotal support. Chines do affect handling (as do shape variations on round bilge boats) but whether any boat handles better than all others is a moot point. The boats associated with these claims may be decent boats with a strong following. They may even be superb boats but that does not make the claims valid and we should not confuse a well-designed boat (whether by intention or accident) with novelty. In some ways modern boats have gotten better. If builders have done nothing else they have recognized that one configuration and one concept does not fit all. Unfortunately one must try a lot of boats to find the one that fits "best" and that assumes the paddler knows what constitutes "best" and how to evaluate it. I look with scepticism upon "experts" who can paddle a boat for a few minutes and pronounce judgement on it. Indeed, so many builders claim their boats are the "Best" that the word has lost all meaning. The best of what? By what criteria? By whose criteria? Superiority and design breakthroughs come easy to those who write ad copy. Most "great" boats come from the fortuitous meeting of the right boat with the right paddler. So, have there been any innovations in kayak design in the past century or so? Speaking as designer and a cynic I would list these as the significant design innovations (not in any order of importance) in sea kayaks: • The first folding sea kayak. • The first sea kayak actually designed to a specific displacement. • The first sea kayak that did not mimic traditional boats. • The first sea kayak with a hull designed to fit a specific power output. • The sit-on-top sea kayak. The first and last can’t be classed as hull design innovations but they did change our thinking about what a kayak "is" and I don’t feel like it stretches the point too much to include them. This is not a big list and maybe I have too small an imagination. In any case, each of us has the opportunity to find the right boat for ourselves and when we find that boat it may seem like a breakthrough – in our own minds.

Published with the permission of John Winters

spacer

 
Copyright 2000 - 2004 Miro International Pty Ltd. All rights reserved.
Mambo is Free Software released under the GNU/GPL License.
spacer