Kayak Building
This page started out as a collection of information about building boats. It has since evolved to have an emphasis on building wooden kayaks. If you are interested in how to build a kayak, this is the place to bookmark. There is information here about all different methods of making sea kayaks including: strip-built (or wood strip, cedar strip, etc.); stitch-and-glue (or tack-and-tape); traditional (or skin-on-frame, wood and canvas); and some others. I hope you find what you need. I'm always looking for more information to add. If you are building a boat, keep a journal. It may find a home here.
Strip Built Construction
Strip building is the craft of turning a pile of thin strips of wood into a high-performance, durable boat. It is a great way to make a boat. It produces beautiful results that are also lightweight and strong. It may not be the quickest method to make a boat, but the individual steps are really not hard. It is a matter of shaping relatively small pieces of wood so they interlock tightly. The goal is to cover the boat with wood, and this simple idea permits a lot of room for creativity. Below are some pages that will describe and show some of what can be done
Cove and Bead Strips
A strip built boat is made of small strips of wood so if you were wondering where the name came from, now you know. The method is often called cedar strip, because the wood used is typically cedar. It does not have to be. Any straight grained, light-weight wood can be used. I have used redwood, pine, and mahogany as well as Alaskan cedar, western red cedar, northern white cedar, and atlantic white cedar.
The reason you want straight grained is because you will be bending the wood around forms. This stress will break wood with poor grain. For this reason you also want to avoid knots. They cause a weak spot and are also hard to smooth when you start fairing the boat. You want light weight, because you want a light boat. If you don't then ignore this advice.
The strips are typically cut out of a 3/4" thick board. The 1/4" thick strips are cut off the edge of the board with a table saw or band saw resulting in 1/4" by 3/4" pieces. These strips can be used as is or you can mill them further and make cove and bead strips.
Cove and Bead
Cove and bead strips like the one on the left have a 1/4" diameter groove cut in one edge and the other edge is rounded over to a 1/4" diameter. The strip thus becomes like a tongue and groove board. The bead nestles neatly into the cove ensuring a tight joint.
There are several advantages to this. The first is a light-tight joint, you won't get any embarrassing light shining through your hull. The surface stays smoother because the joint assures that neighboring strips stay at the same elevation. Because of this, you don't need as many staples. Finally all the above happens while you are stripping around bends.
Natural
If you just leave the edges "natural" you will end up with grooves between the strips. Structurally this is not too big a problem. The grooves tend to be small and they will fill up with epoxy. It doesn't look good however, and the boat will be lighter and stronger if you don't have the grooves. Since the grooves fill up with epoxy, you are adding the extra weight of the epoxy unneccessarily. If the groove does not fill up there is room for the structure to collapse.
Planed
To fix these problems you can plane the edges. With care this will create nice tight joints. There is nothing wrong with this technique. I've built my boats this way for years. With a little practice you soon become proficient at planing in a rolling bevel that changes as the shape of the boat varies. It does take practice and patience to do a good job. Luckily perfection is not required. Like I said about the natural edges, any gap will fill with epoxy.
I've also found that with some of my more compex shapes, especially those with hollow sections, that the cove and bead actually makes the strips want to lift off the forms. The geometry of the cove and bead makes them most comfortable when there is only a small angle between adjacent strips. With more extreme curves, the bead may lift out of the cove creating a gap. This gap may not be visible until after you have done some sanding. Because of this, when I want the tightest joints between strips, I will often take the time to individually hand bevel each strip instead of using the faster and easier cove and bead.
The advantage of cove and bead strips is the cove accepts the bead even when it comes in at an angle so a tight joint is assured even around fairly tight corners. The disadvantage of cove and bead strips is you need to make or buy them. You can find several sources for cove and bead cutting router bits. You then run the strips one-by-one through the router for the bead and then the cove. Even with good tools this is not the easiest task. Again it takes some patience. You need to be careful not the make the edges of the cove too fine as they will be delicate. The average router bit is 1" in diameter and this small size can result in tearout and ragged edges.
It is hard to say whether cove and bead strips are worth it. They make the boat go together faster, but you pay for it with some additional time up front if you are cutting your own. You will pay a bit of a premium if you buy pre-milled strips, but chances are they will be better than strips that you can make yourself and you save quite a bit of labor time.
Length of Strips
The tendancy is to try and use full-length strips. It seems logical that one strip that is long enough to span the full length of the boat would be easier than piecing together several shorter strips. For some parts of the boat this is true, but not always. You would also think that avoiding joints in a strip would creating a stronger boat. This is not something you need to worry about.
Short strips are actually easier to work with sometimes. A 18' strip needs to be handled with some care. It is hard to move around a shop. A 9' strip is alot easier to handle. When you get to the bottom of the boat you need to taper both ends of a strip to fit into the remaining space. The shaping of the taper requires some precision fitting for tight joints at both ends. It is easier if you fit one end of one strip and the other end of another, then fit a joint between them somewhere in the middle.
Short strips need to be joined together to fill the same space as a long strip. This can be accomplished with several different scarf joint. The simplest is just a butt joint. Cut the ends of the two strips square and push them together. This is easy and does not substantially weaken the boat once it is covered in glass. The only reason to do any other kind of joint is cosmetic. You can cut a joint diagonally across the strip or diagonally through the strip. What you do depends on what you want it to look like.
Grain
The grain of wood is defined as either "flat" or "vertical". In flat grained wood the growth rings are approximately parallel to the surface of the board and in vertical grained wood the growth rings are perpendicular. Either variety can be used for strip building but vertical grained is easier to work with.
In the figure above the growth rings are rising to the surface as they would in flat grained wood. Different regions in each yearly growth ring are of different densities. The different densities sand at a different rate. With good sharp sand paper such as (a) above, this is not a big deal. The difference between the soft and hard is not significant because the sharp grains of sand can still cut the hard sections. As the grains get dulled (b), they can no longer cut the hard stuff easily, but they still cut the soft wood easily. As a result you can get a ripple in the surface. This ripple will show up in the finished boat.
Vertical grained wood is easier to use because the grain does not rise to the surface in the same accute angle as it does in flat grained wood. As a result the hard part of the growth rings is much easier to cut through. The grain is also much closer together so the sand paper can not reach into the soft part of the wood as easily which is what causes the ripples.
You can avoid the rippling problem by using a plane to do most of your fairing, but even planing is easier in vertical grained wood.
Notice in the above illustration that vertical grained strips are cut from flat grained boards. This can be a problem, because generally the best wood is cut into vertical graind boards because vertical grained boards are less likely to warp. While warping is not a problem with strip-built boats, if you want vertical grained strips, you will want to find flat grained boards.
The illustrations used on this page are extracted from my book "The Strip-Built Sea Kayak"
Stitch and Glue Construction
Free Stitch and Glue Kayak Plans
I've decided to make the plans for my Stitch
& Glue Guillemot available to internet users as "share
ware". If you end up building this boat please send me a
photograph of the results.
If you don't want to deal with lofting from the offsets, I have
full sized drawings available.
You can read my experiences making this kayak in the journal
I tried to keep as I built it. For now the journal will have to
suffice for building instructions. After some sea trials I feel
that it is a pretty good boat. Not as nice as my
strip-built designs, but respectable.
While building it I had some trouble with the shape. I feel the
problem lies in my building technique not in the panel shapes.
Some forms distributed along the length while the seams cure should
help the problem. I'm not suggesting a strong back, just cutouts
inserted in the right place until the epoxy cures.
Click on the graphics below
to get text files of the offsets
Panel offsets (all units are Inches)
Forms offsets (all units are Inches). These forms may not fit
at exactly their design location. Use them as guides for the shape.
The hardest part is the ends.
Once you have epoxied the hull it becomes very stiff, especially at the ends.
You will not be able to adjust it to fit the deck.
I suggest temporarily stitching the hull and the deck (no epoxy) and then matching
them together dry, so you can see the proper shape. Locate the forms so you
can reproduce the right shape. This is a very complicated shape for a stitch-and-glue
and it will be difficult to make work.
John Coppens has a nice set of pages describing the kayak
construction process. His description is in both Spanish and English
These plans are not are NOT PUBLIC DOMAIN. I retain copyright on this design and reserve all rights.
Hybrid Kayak Construction
Hybrid construction could mean any method of building a boat which combines two different building techniques. In the case of kayaks it typically means building the hull using stitch and glue methods and the deck using strip building techniques. This offers the ability to quickly put together a hull using plywood, while getting the beauty of a strip-built deck.
Skin on Frame Construction
The original kayaks were built by the Inuit and Aleut "Eskimo" peoples of the Arctic. Living above the tree line they did not have access to unlimited supplies of wood. Instead the built boats using a light weight driftwood frame that they covered with skins. Typically these skins were from seals, but whale skin and cariboo skins were sometimes used. Modern Skin on Frame kayaks typically use synthetic fabric such as Nylon or Dacron. Some builders use cotton canvas.
Advantages of Skin on Frame
The big advantage for the traditional builders of skin-on-frame kayaks, the Aleut and Inuit residents of the far north, is they could be built with the materials on hand. The frame did not require big pieces of wood and could be made with material that drift up on the beach. The skin was made from their primary food species, the seal. This set up an interesting chicken-and-egg situation, because they needed the kayak to catch seals and they need seals to make the kayak. The resulting boat was light weight, rugged, resiliant and easy to maintain.
Today skin-on-frame kayaks are made primarily by enthusiast interested in the traditional ways of the originators of the kayak. However, this method of making a boat offers some advantages to the modern kayak builder. The advantages are similar to the Eskimo's, the materials are inexpensive and easy to obtain. A few boards and a little cloth and you can probably build yourself a kayak. The resulting kayak will be light weight, rugged, resiliant and easy to maintain.
Baidarka
The word "baidarka" is actually a Russian word. It is the diminutive form of "baidar" which means "boat" so "baidarka" means "small boat". In modern use in the United States, it has come to mean a skin on frame kayak of the type made by the Aleut peoples of Alaska. This usage probably stems from George Dyson's excellent book by that name Baidarka. This book is a good reference for anyone wanting to know more about the subject.
The Bifurcated Bow
The kayaks made by the Aleuts were unique in form and construction. The most obvious feature is a "bifurcated" bow. The front of the kayak is divided into two parts, one above the other, like the open jaws of a salmon. The lower jaw may be straight, jutting horizontally out in front of the boat, or it may be go out straight initially and then curve upward. The upper jaw more typically sticks straight out front, but sometimes it too will curve upward.
There has been a lot of speculation regarding the function of this bow form. The most obvious is it is a way to give the bow a "hollow" cross-sectional shape. The advantage of this shape is at the waterline the lower jaw can be narrow and sharp, giving a fine entry into to the water for good efficiency, while higher up the upper jaw can be full and wide for high buoyancy to lift the bow over waves. Because the skin wants to stretch straight across from the narrow bottom to the wide top so the entry at the waterline would either be wider than you might want or if you make the entry narrow, there may not be much buoyancy. If you stitch the two sides together part way up, you can get the best of both worlds. But now you may have holes where the stitches are. If you instead cut out between the upper and lower section, you can stitch the two sides together with more waterproof stitches.
The "Bulb" Effect
Modern oil tankers, bulk transports and other large ships often have a "bulb" sticking out front underwater. This bulb improves the efficiency of the boat by reducing the size of the waves it produces as it moves through the water. People have speculated if the lower jaw of the baidarka might serve a similar function to make the kayak more efficient. If it does, it can only do so while the bulb is underwater. Unfortunately, kayaks are typically paddled in large waves. This will lift the bulb out of the water where it can do no good. In fact their might be some loss of efficiency due to the effects of the lower jaw re-entering the water. Since the end of the lower jaw often curves up on traditional baidarkas, they are often not properly shaped to work as a bulb, even if they did stay in the water.
Since we can not go back and interview the original developers of the baidarka, we can only speculate regarding their intentions when the created the bifurcated bow. The best evidence of the performance of some baidarkas is inlog reports from early European explorers. Their reports suggest paddlers capable of maintaining speeds near 10 knots for sustained periods. Careful reading of the reports suggest the paddlers might have been surfing. Reliable reports of these sustained high speeds disappear from the historical record around 1800. There is very little record of the designs of the pre-1800 boats but there is reason to believe the boats differed substantially from those built in the later parts of the 19th century and early 20th century.
Hull Flexibility
Due to the construction technique and materials used, any skin on frame boat is inherently flexible. There is some thought that this hull flexibility offers some efficiency advantages. There is some anecdotal evidence supporting this idea, but the evidence is not clear cut one way or the other.
Designations and Terminology
Unfortunately due to the popularity of Mr. Dyson's book, the term baidarka has become the generally accepted word in the kayaking community for the kayaks made by the native peoples of northern Pacific and Bering Sea. Some people find the term offensive as it was given by Russian colonizers during the conquest and subjugation of these peoples. The word "baidarka" is the diminutive for of "baidar" or boat, so a baidarka is just any small boat. The term serves a useful purpose in that it distinguishes the kayaks made by these peoples from those made by the Inuit peoples of Greenland and northeastern North America. However, there are many, widely different kayaks made by the peoples of north western North America and eastern Siberia which seem to fall under the term "baidarka" in popular thought. As such it is not a useful term for making any meaningful generalizations regarding performance.
The designation "Aleut" has traditionally been used to refer to the native people of the Aleutian Islands as well as the Kodiak Island archipeligo and mainland locations near by. As such it is also a somewhat deceptive designation. In fairly recent times there has been some effort to use more accurate designations.
Material Sources
