Post-covid (starting Sept. 2025), my company adopted the "Return to Office" policy, with formerly hybrid workers now required to be in the office 4 days a week. This has flip-floped my schedule of being at the boat in Kemah vs being at home in Austin. Since I will now primarily be at my home in Austin - it may be time to build another kayak.
Chesapeake Light Craft is well known for providing plans and kits for a variety of boats designed to be easily constructed by home boatbuilders.
Important note: A set of plans from CLC provides a SINGLE license to build ONE boat. Technically speaking, you are not allowed to buy a single set of plans and build a pair of boats. Legally, you are expected to order a second set of plans for the second boat.
I ordered a set of plans for the Mill Creek 13 to use as an example and design influence for my own work. The Mill Creek 13 is a nice looking boat intended for stitch and glue construction, for use cruising on calm bodies of water (calm creeks, lakes, rivers, etc.).
While there is a lot I like about this boat, things I might change include the cockpit shape and the displacement. While the arrow shape of the cockpit is attractive, the shape I used on previous boats with a large bulkhead in the back, and a slightly less cockpit width forward provided a shape that was easy to work with, and easy to get in and out of, without an excess of open area on the deck.
The Mills Creek is designed for a paddler weight of 125 - 250 pounds. Max payload of the boat is 300 pounds.
As a senior, "full figured" adult - I would be pushing the boundaries of these limits, especially if my boat construction ended up being heavier than the designed weight of the boat.
The boat features a flat bottom and two side panels, with a curved deck. This provides a pleasing shape while retaining the flat bottom to make transportation easy.
The Sectional Sheerwater Sport is an interesting design. Basically, it's a Sheerwater Sport except with double forward and aft bulkheads. The boat is built as a single hull, then literally cut into 3 sections between the double bulkheads. The double bulkheads have a neoprene seal applied, and are bolted or unbolted to allow the boat to be easily disassembled for transportation or storage.
The design has a slight V-bottom with a single side panel and a curved deck. This makes for extremely simple construction using stitch and glue, and yet still provides attractive lines. The challenge of the v-bottom is in transportation and support on dry ground. Best practice would be to construct a carpeted cradle to support the boat on land. At a minimum, two carpeted 2x4's or 4x4's might suffice. I'd have to check the angles to see what might work best...
I've studied the plans above, and others of various styles. There are parts I like about many designs - but a core driver of most engineers is that we can't look at ANYTHING without thinking, "I could make that better if I just tweaked <this>...". Engineers want to fix things, or improve them, or at least just change them to leave their own touch on it.
In my case, I have built simple kayaks before - but due to limitations of space and number of available hands (I generally do not have a helper available), I am considering construction technique as much as boat style. Below I will list several common boat construction methods, and then in some cases give hybrid approaches.
Stitch and Glue
This is the traditional method used for CLC boats (and many others).
The problem that I have with stitched boats is that there is no frame on a strongback to keep the boat straight when it is stitched together. A video in "The Art of Boatbuilding" series shows construction of a kayak, in which he attached sticks to the sides, and clamped them to the sawhorses to check for true-ness.
One alternative I've seen lately to traditional stitch and glue is to use zip-ties instead of copper wire for the stitching. This is a minor tweak - but has the advantage of not leaving a piece of copper wire in the boat, and not having the wire edges to hit when sanding and fairing.
Skin on Frame
Skin on frame boats go all the way back to Inuit kayaks built using whale bone frames with skins stretched across them. Modern skin on frame boats can have aluminum tubing, may use high density plastics for frames, and use high tech fabrics for the covering.
After studying this approach, I tried an experiment where I built a very simple frame section, glued canvas over the frame, using contact cement to hold the canvas to the wooden longitudinal pieces. I had also tried stapling the canvas to the wood, but it didn't give a smooth result. Once the canvas was stretched over the frame, I applied a couple of coats of epoxy. The idea was that the epoxy would harden the canvas, and give a tough shell on a boat that was easily constructed using frames and long battens. It was a nice idea - but didn't work out... The epoxied canvas dried with a wavy texture between wood elements, since there was no mold to support it. The epoxy caused the fibers on the canvas to stand up and poke out. It would have taken a LOT of sanding, and multiple coats of epoxy to fair. To get a solid structure, multiple layers of canvas or possibly fiberglass would have been required - which could have made the boat heavier than a wood boat.
Traditional Planking
There are two common methods for plank building boats. One is "carvel planking", where the planks are fit edge to edge. The other option is "lap strake", where the planks slightly overlap each other, allowing a strong glue joint at the overlap.
Both of these could be modified for kayak construction. In fact, stitch and glue construction is similar to carvel planking in that the planks fit end to end with no overlap.
A hybrid planking scheme could be imagined where a strongback is used with regularly spaced frames. The planks could be attached to the frames - but then could also be zip-tied closely between the frames to get a close fit before a layer of fiberglass covers the planks. Once removed from the construction frames (station frames detached, but bulkheads left in place, or narrow frame sections removed from station supports), the hull can be flipped right side up. Then fiberglass tape can be epoxied along the seams on the inside of the planks. Wood planks with a layer of cloth covering the outside, and fiberglass tape re-enforcing the inside of the plank seams should give a very strong hull structure.
Flat Bottom vs V-Bottom
As mentioned previously, there are trade-offs between v-bottoms vs flat bottoms. The v-bottom will have different handling characteristics and may look better. A flat bottom will rest easily on the ground, car racks, etc. A flat bottom can be easier/faster/simpler to build.
After far too many hours overthinking this... I may decide to go with a very simple approach for my next full size boat experiment. I'm considering a boat with a flat bottom, single side panel, angled at about 65-75 degrees to the plane of the bottom, and a curved deck. This is an extremely simplistic approach. Hopefully the angled sides and curved deck will keep the boat from looking too boxy. Once in the water, it should look fine. An unknown here is how stable this might be - though it would essentially be a small, decked pirogue. Thinking of it that way makes me feel a little better about the sea-worthiness of the flat bottom with flared sides.
Length: 12'
Beam: 30"
Height: 10-12" at the sheer line, at max beam.
Deck height: 2-4" max above the sheer height.
Stem height: 12"
Stern height: 10"
Stem and Stern rake: TBD? May be straight for first boat to keep things simple.
Displacement: Goal is to have a displacement of 325-350 pounds at 5".
I recently rented a sit-on-top kayak on Town Lake in Austin. This was the first time I'd paddled in a number of years. I'm older now, and was surprised to discover my creaping loss of flexabiility may have a significant impact on my ability to enjoy paddling a kayak. My left foot went numb within minutes, along with my lower back expressing significant unhappiness.
A boat seat would help with this. But I will also need to see if my body can adjust to sitting in the "box" of a kayak. I may have to start working on stretching exercises to see if I can return the flexibility to be able to sit comfortably in a kayak for at least an hour.
The plans for the Mill Creek 13 included plans for a slatted seat. To me, the provided backrest was less than half the height that it should have been. I traced the plans and cut out the shapes for the seat bottom and seat back. But I will probably alter the spacing of the back rest parts to be the same width as the bottom supports - and then use extended lengths to experiment with different back rest heights.
Ultimately, I have considered going so far as to mock up a "cockpit box" to see how hard it is for me to get in and out, and to allow me to sit in the box with the seat for an extended period of time to see if I can do so comfortably.
The proposed kayak design experiments can be constructed using several different tools. Onshape will be used to do the CAD work. It can also help with the design task by assisting with CAD generated lofting. But this, I mean that the lines of the proposed design can be entered using minimal points, then stations created along the length of the boat, and design dimensions measured at station increments.
Alternatively, much of the design could be generated by computer routines running the math.
The boat curves can be approximated using several options. Easiest would be to simply fit an arc of a cirle from the stem, through the beam, to the stern. An option giving a little further control would be to fit the arc from stem, to forward station point, to beam, then a second arc from beam to aft station point, to stern. The station points would be presumed to define the radius for the arc, and may not give a smooth curve - or at least not the desired curve.
Using an ellipse instead of a circle arc would allow still further control, as the ellipse would use the station point as a control point for the ellipse. If fore and aft ellipse curves are used, then care would need to be taken to ensure a smooth transition at the beam point.
The best fit option would be to used a spline curve. This is easy to do in CAD, would allow multiple points to be entered, and would remove the concern about the transition at the beam.
A spline curve can be mathematically computed and derived into a series of formulas, using any number of points (though limiting the points might be better than over-constraining). A program generating the equations can then easily provide x, y, and z values as the routine steps through station points.
Generating the program to calculate spline based points is more complicated than either a circle or ellipse arc - but AI is happy to do that work. Once the program is written, entering 3 points is as easy as entering 5.
The first experiment will be to start drawing curved surfaces in OnShape.
The first experiment will be a simple curve. The first curve can be defined by the length of the boat, with the max beam defined to be at the mid point of the length. We will assume the side will have a 70 degree slant.
Equation: tan(70) = opposite / adjacent
adjacent side length = opposite / tan(70)
10" / tan(70) = 10" / 2.7475 = 3.64"
Shifting the end and mid curve points laterally 3.64" will give the lower curve - which will need to be trimmed at the ends where it crosses the axis.
Constructing this curve in Onshape, and then trimming the ends extending past the origin axis yielded a length of the bottom curve of 125.974", for a curve that extended 15 - 3.64 => 11.36" from the center origin of the bottom of the boat shape.
This gives a simple curved shape to experiment with in Onshape.
See Onshape notes under Lofting. The shape was created by forming the upper and lower arcs. The Loft function was used to create a shape. Then, the analysis tool (protractor in lower right corner) was clicked, with the flatten function selected. That shape was exported to a DFX file. A new drawing was started. The DFX was imported, and measurements could be taken. However - the curves of the DFX did not import cleanly into the drawing. The arcs would have to be re-created in yet another new view so that details could be taken for laying out the physical wood panel... This seemed to be a limited and painful process.
The 2nd experiment will explore creating points to form spline curves. A set of initial guesses for bulkhead points will be made - stem, stern, and fore/aft bulkheads. Those points will be plugged into Onshape so that splines can be drawn. The bulkhead points will be adjusted until acceptable splines result. The resulting bulkhead points can then be plugged into a program to generate the spline curve equations. The equations will be iterated over to generate station points. The 3D station points can then be flattened by algorithm (another program) to give the offsets for a flattened panel.
Onshape can also be used with the spline curve model to split sections and estimate displacement.
Parameters:
Halfwidths: X axis, Heights: Z axis, Length: Y axis
LOA: 12' (stem 144" from stern)
Max beam: About 30"
FW Bulkhead at 108" from stern
Aft Bulkhead at 48" from stern
Initial Fwd/Aft sheer height: 10"
Initial Stern height: 9"
Initial Stem height: 12"
Initial Bulkhead sheer halfwidth: 15"
Initial Bulkhead bilge halfwidth: 11.4"
Initial stern bilge Y: 4"; Initial stem bilge Y: 140"
The third experiment will attempt to generate better curves for the lines.
First, a curve will be fit from the bow sheer point, to the beam sheer point, to the stern sheer point. The height of the FW and AFT sheer Z points can be taken from this curve.
Next, a curve will be experimentally fit for both bilge and sheer, from the stern, to aft, beam, fw, and finally stem points.
Cockpit box needs to be 4'6" long.
Cockpit opening length needs to be 3' long.
Beam at aft of cockpit needs to be at least 22"
Drawing name in Onshape: BoatCurve4
LOA: 144"
Bow and stern raked in 4"
Bow raised 3" from fwd bulkhead
Bilge is flat from fwd bulkhead to stern.
Max beam of 30" at Y=72", Z=10"
FWSheer 13.5", at Y=96", Z=10.87"
AftSheer 13.5" at Y=48", Z=9.87"
Bow sheer Z=14" at Y=144"
Bow bilge Z=3" at Y=140"
Stern sheer Z=11" at Y=0
Stern bilge at Z=0", Y=4"
Note - minimal sheer height projected at Z=9.838" at Y=56"
Bilge inset Adjusted to 3", for 73 degree angle at max beam, to give bilge beam of 22" at bulkheads.
The 5" displacement level gave a displacement of approximately 394 pounds.
4" of displacement gave approx 308 pounds.
4.5" of displacement gave approx 351 pounds.