help finding research material kayak design

[breschau]

Greetings to all forum dwellers,

I have been trying to learn about kayaks since I have decided to make one. Although this forum slants more towards bigger boats, I have learned a lot. Saying I have learned about boat design will be folly, I rather learned how complicated it is. I wish to go more technical but the kayaking books I could find dont look all that technical. There are books about building a few preset designs, there are books about traditional designs of certain areas, there are books about using the kayak itself. Design information presented is generally sketchy or subjective. Like, flat bottom for initial stability, v-section for tracking, secondary stability offers more seaworthiness etc.

How do I find numbers and mathematical presentations of the concepts? Like how to measure tracking? How to distribute buoyancy? Basically is there a text book on boat design that deals specifically with kayaks?

[DCockey]

John Winters has written about canoe and kayak design in a somewhat technical manner. Brief articles by him are available at:
http://www.greenval.com/jwinters.html#technical articles
http://www.boatbuilding.com/article.php/ShapeoftheCanoe

He also wrote a monograph, The Shape of the Canoe, which has 74 pages of text, a 9 page glossary and 64 illustrations. Even though the title is the same as one of the articles in the links above, it's much longer. Available at http://www.greenval.com/Shape_of_the_Canoe.html
The CD also includes his performance prediction program, Kaper, and an experimental directional stability program.

[breschau]

Already read that, good general information. Still has similar problems. Check the quote below:
"Should the stern be filled out too much directional stability will suffer and, if it is too fine, there will be a loss of control in following waves."

Nothing numerical. how much is too much? It sounds like he knows about the matter but it doesnt help me calculate anything.

Another quote:
"The surprising thing (or perhaps, not so surprising) is that the application of this knowledge to canoes has been largely superficial despite great strides in the materials used. "

A real showstopper.

[terhohalme]

Yes, true, you can't find a simple equation to design a kayak, canoe, boat, sail boat, ship or anything that floats and moves on the water. The holy grail is to understand all the vital principles of hydrostatics and hydrodynamics and then apply those to your kayak design.

If you study (not just read) John's CD and some other books of hydrostatics and hydrodynamics you can find something to calculate and lot of things to estimate.

Terho

[kerosene]

and most often there is no perfect boat - at best a decent compromise. Small changes in the intended use makes one boat better than another - in other conditons/use the situation can easily reverse.

What is your kayaking experience?

If you have kayaked a lot you should try to try different boats to get an idea of the impacts of different changes.

if you have little kayaking experience don't design one but rely on plans done by people with more experience.

[breschau]

I am not looking for a magic wand nor am I looking for a perfect boat. I just find it less than efficient to read a book on yacht or cargo ship design to design a kayak. For example the paddle stroke of a kayak is not the same as ship propulsion. There is no point buying a design book if it doesnt cover the force vector calculations of kayak paddling. The keel line of a kayak has to resist that force to be able to track well. Reading about yacht keels may give insight on that but wouldnt that be like sieving a mountain for a particular pebble.

Trial and error is always an option, just trying to find out if there are any specific documents on the subject. If there is none I will just read basic hydrostatics and make some models.

[cthippo]

You may be over-thinking this.

A fair number of kayaks, especially traditional skin on frame boats are built without measuring anything. I'm not trying to discourage you from designing your own, rather saying that the process doesn't need to be as complicated as you're making it out to be.

[gonzo]

http://books.google.com/books?id=1ad...0plans&f=false

http://dashpointpirate.typepad.com/t...d-chapell.html

[breschau]

Dear Gonzo, that was the most comprehensive analysis I have seen so far. Looks like a lot of the circulating info and line drawings on the web may be coming from this work. That's not exactly what I am looking for but I will try to obtain one for through reading.

Dear Cthippo, it may not that hard to make something that floats and looks fine. I am just perplexed by the scarcity of material. Thinking maybe someone on the forum knows about a research paper or text book on one man craft, that might be obscure for the outsiders of the field. When a salesman says "This kayak tracks well", I will ask "What percentage of stroke power is translated into forward motion after deducting resistance factors?". Its my curse, I live with it.

Apparently trial and error is the way to go, can anyone recommend a practical material for building scale models

[breschau]

http://www.rayjardine.com/papers/cannonballs/index.htm

This nicely sums up my outlook on most commercial outdoor gear, the man is a prodigy.

[cthippo]

Originally Posted by breschau

http://www.rayjardine.com/papers/cannonballs/index.htm

This nicely sums up my outlook on most commercial outdoor gear, the man is a prodigy.

Sure, but what he's saying is step outside your pre-concieved notions of what a piece of gear, in this case a kayak, should be.

So, setting everything else aside, lets start with a working definition of "what is a kayak?".

My preferred definition is "a narrow human powered vessel designed to be paddled from the center of the boat". This sets it apart from a canoe which is paddled from the ends of the boat or a skull which is rowed.

Once we get past the basic definition then the possibilities spread out rapidly. Sit on top or sit inside? 1,2, or 3 people? What do you want to use it for?

Once you have answered these questions you can get into materials and constructions methods and sizes and the rest of it.

[breschau]

???
I dont have pre-concieved notions about kayaks. That article is about the general trend of outdoor industry to advertise without data. I asked a material not for the kayak but for scale models. Do you need to make them with the same method as the final boat?

[DCockey]

"Kayaks of Greenland" by Harvey Golden is by far the best source of information on traditional Greenland kayaks. http://www.traditionalkayaks.com/ It includes lines drawings (with scales) and major dimensions for 104 Greenland kayaks from the last 400 years which Harvey has measured. There is table comparing their proportions but no offsets. Also none of the "naval architecture" coefficients such as D/l or prismatic coefficient. Harvey did include a short section on how to take offsets from the drawings with a pair of dividers. Someone with sufficient time and motivation could lift offsets from the kayaks which interest them, model them in a suitable computer software, and then calculate the desired coefficients.

One thing anyone interested in replicating one of the designs from Harvey's book is that the original was probably built to suit the original owner. If the user of the replication will differ significantly in size or proportions from the owner then an adjustment of the design may be called for.

[DCockey]

The reviews in Sea Kayaker magazine include a page of technical data including a number of dimensions, hydrostatic coefficients and stability curves. An example is at http://www.seakayakermag.com/2010/De...ras_Tspecs.pdf
These could provide a starting point for a sea kayak data base.

[Doug Lord]

This may help-click on Design terms and Stability:

http://www.guillemot-kayaks.com/guil...n/kayak_design