Building a Wood Duck 12

The Wood Duck 12 is a recreational kayak from Chesapeake Light Craft . It is 12 feet long with a massive cockpit opening which makes it as easy to get in and out of as a sit on top kayak. With nearly 3 feet of beam, it is very stable, yet the advanced hull shape is also fast and easy to paddle. At the CLC Annapolis Demo Night I was able to get it up to hull speed, 6.4 mph as measured by GPS. While not a racing kayak by any means, 3 hours of easy paddling will get you 12 miles. The stability is such that you will fall out of the boat before it tips over. If you do, wet re-entries are easy, thanks to the large cockpit. The short length will get you through marshes and swamps as easily as a pirogue, and the target weight of 40 lbs will be the envy of every clorox bottle plastic kayaker. The kit is available at CLC Wood Duck kits.

Picture courtesy of Chesapeake Light Craft

Page 2 - Hatching a Duck
Page 3 - Stem & stern pieces
Page 4 - Interior fillets & glass
Page 5 - Glassing under the deck
Page 6 - Installing footbrace mounting studs
Page 7 - Building the coaming, attaching the deck
Page 8 - Exterior glass
Page 9 - Graphite bottom, invisible hatch hold-downs
Page 10 - Final outfitting

Click on any image below for a larger view

Cartopping the Duck for the first time.

The box in front of the truck contains the epoxy kit, the box on top everything else. Epoxy kits packed for shipping, instead of pickup at the store, are more carefully packed.

The kit, ready to open

Sort of magic that an entire kayak fits into that box. All a builder has to do is add roundness. The box, BTW, is about 33 by 100 inches.

The Kit

Mostly wood at this end, glass & hardware at the top. The coaming is being especially obvious. The little dark oval is the hatch stiffener. The chords are the underdeck formers. The little wedge is the transom. The puzzle joints are also being obvious.

Big Coaming

Here's the Duck's coaming overlaid onto a Chesapeake 16LT. Note how the entire Chessie coaming completely fits inside the opening of the Duck coaming with lots of room to spare. This is what makes the Duck as easy to board as a sit on top. Those of us with old knee injuries find this a very nice feature.

Gluing the Panels

The obligatory picture of the first step in actually assembling a kayak. No scarf joints here, just fit the jig saw puzzle joints together. Some builders find this easier than scarf joints, but on a Chesapeake Light Craft kit, both joint types are pre-cut at the factory, so I don't see much difference either way. Scarfs need to be immobilized in all directions, while puzzles self-align in 2 directions. However, puzzles need a piece of fiberglass tape applied and scarfs don't. Builders should be aware that puzzle joints still need care in alignment, just a bit less than a scarf. In my opinion, it's six of one, half dozen of another. Note that the arrangement of joints does not match the drawing on page 5 of the manual. CLC has wisely simplified the assembly by reducing the number of joints.

Initial Stitching

This is the bottom of the boat after initial stitching. Note how the puzzle joints line up exactly. However, at this time, neither the bow nor the stern were properly aligned. This was caused by some kind of a twist which had to be worked out. This is one of the challenges of stitch and glue boats, especially if they have a deliberate strong twist to the hull. This is not peculiar to CLC boats. Probably the only boat that's immune to this problem is the Bolger Brick (and the less said about that boat the better). The only solution is to take one's time and to work the twist out. Until the epoxy is applied, everything can always be taken completely apart, so there's no disaster here. Make haste slowly.

See, by the way, the gouge that crosses the joint on the bottom right panel in the picture. It came that way in the kit and was filled with some kind of putty. It shouldn't be a problem, structurally or visually, since the bottom will be glassed and covered with graphite/epoxy mixture, but I never saw that on BS1088 plywood before.


The twist was worked out and it was time to close up the ends. It did not want to go easily, so I used the clamping method on pages 16 & 17 of the manual. As I was closing the clamps, there was a loud cracking sound. The outer veneer of the wood had cracked back by the stern. Fortunately, it was a small enough crack that I'll be able to repair it, most likely invisibly, even with a bright finish. However, I've never seen anything like that on any of the previous boats I've built.

Try Again

Once more into the breach. This time, I used plastic shrink wrap (available at shipping stores) to hold the ends together. I compressed the ends, wrapped them, compressed them some more, wrapped them some more, etc. until the ends finally met. Using the wrap had the advantage of distributing the stress over a greater surface area of the wood, thereby reducing the risk of another failure. This was the most work I've ever had to do to close up a hull. Some people on the CLC Forum mentioned that using a damp towel would help the wood twist more easily, but that's not in the manual.

The brown mark just behind the plastic, BTW, is where the CNC router burned the wood. It'll probably sand off.


Eventually, the hull and bottom were also joined at the bow. This required the drilling of extra holes to allow more stitches to be put in. The strain on the fewer number of stitches kept pulling them apart. Note the nylon wire ties. They were added because at that point in the hull the strain was so great that the narrow wire started cutting the wood. They also allowed incremental tightening that didn't come apart since the ties have a ratchet mechanism that wire stitches don't. The only downside is the size of the holes, but in this case they should be hidden by the graphite/epoxy.

That scratch by the bow also came with the kit. Seems that this poor boat's wood had a rough life even before some mad boatbuilder started twisting it in many directions at once.

Stitched Hull

Here's a view of the hull after most of the stitching is done. You can see the four frames (forms, molds, whatever) which brace the hull internally. Three of them are temporary. The second one from the back (the one with the 3 black clamps) is permanent and forms the boat's only bulkhead. The reason for all the clamps is that the wood which forms the forms is so thin that it bows under the inward pressure of the sides unless it's reinforced somehow. If you don't have enough clamps, drywall screws can be used on the temporary forms.

Also visible is the interior of the port side puzzle joint. The strip of glass tape is quite obvious since it's had a light sanding to knock down the ridges caused by the strip of polyethylene which kept the weight system from sticking to the boat wood. Note too the light shining through gap just in front of the frontmost form. This is a result of missing holes. That corner of the mold needs 2 stitches, but only has holes for one. The manual says that CLC has drilled up to 95% of the holes, but that builders will have to put in the rest. While I can understand that it may not be possible to accurately predict where all the holes will need to be (due to the different bending characteristics of different pieces of wood), one would think that corners would be obvious. It's no big deal for builders to actually drill their own holes, but first-timers may have some issues figuring out exactly where to put them. In my case, I was trying an experiment to see if the corner holes were actually necessary. They were for the front and back formers, but the middle ones did not need them.


In this closer view it's possible to see how the wood sits well against the middle molds even without the corner wires. It's only in the areas with the extreme bends that extra wires are needed. The puzzle joint for the bottom panels is hidden behind the mold with 3 clamps - a bit of epoxy around the joint is just visible behind the leftmost clamp. CLC & Schade followed good mechanical practice in not lining up the side & bottom joints. Beside yielding a stronger structure, this allows builders to tell if they have correctly lined up the pieces for stitching. The bottom joints are toward the front, the side joints to the rear. Also, if the pieces aren't properly lined up, the stitch holes for the formers will be staggered and the formers won't go in right. Another neat little touch by CLC to help simplify the assembly.


This shot is from the center of the boat looking forward. It shows the beautiful curves which form the bottom. The central ridge forms a strong keel backbone without any permanent framing, giving the boat its incredible lightness. It also acts as a skeg, giving the boat its good tracking characteristics. Having the 2 bottom pieces of wood act as keel, skeg and hull skin, all without any internal framing, is a very elegant piece of design. It's an excellent example of a true monocoque hull where the pre-stressedd skin is a structural component. This kind of design typically yields the lightest boats.

But there is a trade-off. The more highly stressed the skin is, the more difficult it is to build. Still, the builder builds the boat once and then enjoys the performance every time the boat is used, so it's a good trade.

In the Duck's case, it's these beautiful curves which make the ends so difficult to close up. You can see from the picture that in the center of the boat the bottom is nearly flat in the left/right direction. By the time it gets to the bow it has twisted the better part of 90 degrees. At the same time, there's rocker in the hull. That is, the bottom angles up toward the bow and stern. So while it's twisting from left to right, it also curves from front to back. And, to make things worse, it only has 6 feet from center to ends to accomplish all this bending and twisting. Plywood, even as thin as the stuff used for the Duck's hull, fiercely resists bending in more than one direction at once. It resists most where the multi-dimensional change is the most - the bow & stern. Hence the difficulties in closing the hull.

It's not an insurmountable problem by any means, and the resulting boat is definitely worth the effort. But builders should be prepared for a bit of a fight as they torture the wood into doing what it doesn't want to do. While CLC says "The Wood Ducks are among our easiest-to-build kits.", I personally found their Chesapeake 16LT with its greater length and gentler curves much easier to close up.

Tidying up

Once the hull was put together for the first time, it was time to solidify it. Because of my work schedule, I was obliged to leave it for several days before I could get back to it. This is actually a good thing. It allows the boat to get used to its new shape. The wood fibers stretch and relax. It's no longer such a fierce battle to get the bow & stern to close up.

The first step was to take out the temporary formers and modify them a bit. Knowing then what I know now, I would have done this back before the stitching was started. I replaced the clamps on the stiffeners with drywall screws. This has sevearal advantages. First, it frees up the clamps for other uses. Next, it's lower profile than the clamps. This prevents sleeves and other things from getting caught by the clamp handles and causing accidents. It also allows the stffeners to stay on the forms while the boat is being tacked. Finally, because of the stronger joint, you can get by with only 1 piece of scrap wood per former.

Next, I enlarged the holes at the chines to take 2 wires. This allows the side and bottom panels to both be attached to the former at the same time, resulting in a more solid fit. Originally I had been thinking of drilling extra holes, but then it occurred to me that enlargement would be simpler.

After cleaning up the forms, I put them back in and adjusted the stitches to get the fairest shape. When I was done, the hull was solid enough to pick up and move around (as long as I was careful about the wire ends).

Under the Deck

The deck was actually easy, for a change. While the foredeck has a strong camber, it's not the kind of radical twist that's in the bottom panels. It was pretty straightforward to assemble the deck pieces, fore and aft, and then to put in the deck formers. I never felt the need for an assistant, though builders with smaller hands than mine (10 note reach on a piano) might find one helpful.

First thing to do was to clean up the formers. They had the little nibs left by the CNC router when the bit is pulled up. A couple of swipes each with a shinto rasp fixed that right up. While I was at it, I enlarged the wire holes where the the sheer and deck panels would meet so that both sets of wires could be attached.

Then, I pretty much followed the instructions in the manual. The only difference was that where the manual said to tightly wire the forms to the panels, I ended up doing an initially loose wiring. I tried following the instructions first (always a good thing to do), but ended up with a lopsided deck. The reason for this is that unless you're lucky or experienced enough to exactly hit the correct former position relative to the deck panel on the first try, the former will be higher on one side than the other. And if you've wired it in tightly, there's no way to adjust the position. So I cut the wires and rewired the former in somewhat loosely, bent the deck panel and then tightened up the wires a little at a time.. Again, as with the hull formers, the deck formers will not fit exactly. You need to go for symmetry and fairness. Even the deck assembly pictured in the manual is this way.

The bits of interest in the picture - note that not all wires needed to be installed. I got the best shape when I left out a former wire on the right in the foreground and on the left in the background. This seemed to be a result of the way the wood wanted to bend. Your results will probably vary. The color differences are caused by the deck panel being sapele and the sheer panels being okoume. The streaks on the sapele on the right and just in front of the front former are not shadows. They are the original color of the sapele wood. The lighter areas were faded by being exposed to indirect sunlight in my garage. This isn't a problem, though, because once the epoxy is applied, the wood will darken up again (and it's on the bottom of the deck, anyway). One final note - the deck formers can't be mixed up or installed upside down. They are different shapes, so the hole patterns will line up only when they're correctly positioned. Another nice touch by CLC.

Loosey Goosey

Here's the deck ready to be stitched to the hull for the first time. It's starting to look as if it's really going to be a boat. Note the relationship of the puzzle joints - the bottom joints are the farthest forward (visible inside the cockpit), then moving aft come the side panel joints and finally, furthest aft are the sheer panel joints.

At this point, in preparation for stitching the deck to the hull, I drilled out any of the stitch holes near the puzzle joints which had become filled with epoxy. I used a 1/16th" drill bit. Then I rounded up 2 pieces of scrap wood (approximately 3/4" square and a foot and a half long) which were used to hold the deck above the hull so I could reach between the hull and the deck to thread the stitches through.

Tight as Andronicus

Here's the deck temporarily joined to the hull for the first time. The stitch process was pretty simple, exactly as described in the manual. The scrap pieces of wood mentioned above were inserted between the deck and the hull after the bulkhead, and before the front hull former. Next, center stitch holes on the hull and deck were lined up and one very loose stitch was put in on each side. This was to set the initial alignment. Then open stitches (not actually twisting the wires) were put into all the holes. A pair of needle-nosed pliers helped make this process more convenient, though builders with smaller hands may not need them as much.

To ensure fairness, the tension needed to be applied symmetricaly. So the following stitch-tightening pattern was used: Starting at the center, I tightened one stitch on each side. Then I moved 1 stitch forward, tightened the left/right pair, then moved 2 stitches back and tightened the left/right pair. This pattern was continued until all the stitches were tightened.

While I was tightening the stitches, I also made sure that the relationship of the deck to the hull was the same on each side. That is, if the deck hung over the hull on the left it would hang over the hull on the right by exactly the same amount. The fit between the deck and the hull is very unlikely to be uniform along the length of the boat. Near the center the edges may match perfectly, but near the ends the deck fits into the hull. Even the prototype in the manual shows this. Don't worry about it. As long as the change is smooth and happens the same way on each side (fair and symmetrical), it's fine.

Long Duck Deck

Try saying that 10 times real fast. A view along the deck after the initial stitching is done. The slight left twist in the front half of the boat is a camera angle illusion helped along by odd lighting and the curvey sapele grain. That's why twists need to be diagnosed with long sightlines, good lighting and straight edges.

In the Cockpit

Here's a look into the cockpit after the deck is stitched on. This is the front left corner. The front cockpit former has its stiffener still attached. This is possible because the clamps were replaced with drywall screws. The corner hole has been enlarged to allow the wires from both the bottom and side panels to be attached. A stitch passes through the glass tape on the bottom puzzle joint. This required the hole to be drilled out after the puzzle joint was made. The large gap between the front cockpit former and the round deck former above is visible.


The Duck Tail. The deck is on, and the wineglass transom is wired in. The transom's bottom hole was drilled out to a larger size so that it could accommodate 2 wires and another enlarged hole was added near the center to take those two wires. New holes were drilled in the side panels to match the center hole. The sides were loosely stitched, then pushed in one at a time while the wires were tightened. Beveling the edges is crucial here, otherwise everything will pop out.

It's not shown in this picture, but a clamp is necesary to get the shape right where the side panels sit on the bottom ones. With the clamp there, the bottom of the wineglass sits flush with the stern.

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Copyright © 2007, 2008 László I. Mórocz. All Rights Reserved.