Making a Modern Skin on Frame Kayak




Introduction: Making a Modern Skin on Frame Kayak

About: I've been designing and making my own kayaks for over 30 years

I found I had a little time between finishing one project and starting my next significant build. I thought I would be able to knock out a quick project in between. The idea I had was to make a skin on frame version of my microBootlegger Sport.

I was hoping to strip-build one of these last spring, or maybe this fall, but the last video project just took up too much time. With this build, I hope to accomplish two things: make a cool boat for my own use, and try to find a quicker way to produce an informative video.

The boat I’m looking to build is one I designed in 2015 for a customer. I built it for him in 2016 and added the design to my Fine Strip-Planked boat classes and my catalog later that year.

The design really excites me. It is a cross between my microBootlegger Tandem, which is a fairly sedate two-person kayak, and my Petrel, which is a high performance sea kayak. It has elegant lines reminiscent of a 1920 rum runner, with a sophisticated transitional chined bottom shape of my favorite sea kayak. It is shorter overall than the Petrel, but has a similar waterline length, with a little more beam and more room in the cockpit.

As such it should it falls somewhere between my Petrel Play and the Petrel design. A fairly stable design with the ability to move quickly when needed. The microBootlegger is comfortable cruising on a quiet lake or ripping down a wave in a tide race.

I have the strip built design developed and 3D modeled in MaxSurf. This model represents the desired surface shape of the kayak. Since I can build almost any shape with strip planking, I didn’t model in too much construction detail.

The skin-on-frame building style I plan on using is called fuselage frame, where long strips, or stringers, of wood are bent around cross-sectional frames. This is actually very similar to strip-building, except, the frames are part of the finished boat, and there are big gaps between the strips. These gaps are covered with cloth as the skin.

To adapt the strip-built model to skin on frame construction, I need to figure out where the stringers will be and then create the frames to hold them in shape.

I want to keep the stringer shape as simple as possible. One way to simplify the shape is to be sure they only bend in one direction, or on one plane.

To accomplish this I create reference lines in the model. These references can be horizontal waterlines, or possibly diagonals running from the centerline out towards the side.

When seen from the end or body plan view they appear as straight lines, but when viewed from the side, you can see they cut the outer surface in curves. I can then retrace these curves to create stringer locations.

I switch between the different views to see that the stringer curves follow the guides in top and profiles views while staying flat and straight on the reference lines in the body plan.

This design does not have a traditional gunwale or sheer line. It is more of a continuously rounded cross section from the keel to the deck center. As the primary structural component, I am creating an inch and half wide stringer approximately mid-way up the side.

Below that I add a stringer following a diagonal that intersects the waterline.

To recreate the transitional chine I follow a diagonal that runs along the hard chine at the stern of the boat, then towards the bow where that chine softens, I add two separate diagonals intersecting the first at the widest point. I can use these to essentially split the stringer, creating two chines dividing off from the one.

I use a similar technique to create stringers on the deck.

Once I have a series of stringers defined, I can then skin those stringers with a surface. I need to be sure the stringers all run the same direction for the software to handle them correctly, but now I have basic shape for the boat. With a little refining I get a form that is quite similar to my original strip-built design.

The original cockpit is recessed front and back and curved upwards at the end. I want to simplify it to eliminate the front recess and flatten it out while keeping the rake.

This involves sliding the surface controls up or down until the bottom points all lay on a straight line.

With the shapes defined I need to decide where the frames will go. I start by determining the center of buoyancy, place that in the design and adjust the seat location accordingly.

The frames all draw their location off the seat location so I am not sitting directly on a frame, and the footpegs are between frames. And then filling in any gaps as needed.

I then pull the basic frame shapes into Vectorworks where I start placing stringers. The main stringer is oriented vertically along each frame.

I just place a representation of each stringer where it should cross the frame. The orientation of the cross section is determined by the angle of the diagonal and how the stringer will touch the skin.

The stringer sections are then clipped or subtracted from the frame shapes.

The fabric that will make the skin can stretch a bit when the kayak is sitting in the water. I don’t want the skin to rub and abrade on the frames so, I curve in the edge between the stringers by subtracting sections of circles.

The centers of each frame gets cut out to save weight and so your legs have some place to go. I thought I would just offset the frame perimeter by a uniform amount, but this created funny shapes. I decide to instead base the shape of the hole on the outer skin shape and offset from there.

My plan is to stitch the skin to a flat plywood section around the coaming. To facilitate that I thought it would be a good idea to punch a bunch of stitch holes. Since I’ll be cutting all these parts with my CNC machine, the vast number of holes shouldn’t be too onerous.

Once I have got all the parts defined, I need to lay them out on plywood for the ShopBot to cut. I can do a bit of nesting and in setting to try to be efficient with the material.

Step 1: Cutting the Forms and Milling the Stringers

After arranging the parts in Vectorworks, I exported a DXFand brought it into VCarve, the CAM program for my ShopBot. Here I generated tool paths and added tabs to secure the bits in place as the parts were cut.

On the ShopBot, I start by zeroing everything. First the X and Y axes by letting the tool find its limit switches, and then with a zeroing plate on the table. The tool senses when it touches the plate.

I then load up my plywood. My ShopBot has a 24 x 48” work surface, so I cut my plywood into quarters. A few screws in each corner secure the material in place.

I use a quarter inch down-cut carbide router bit to cut the parts. The down-cut action helps press the material in place. The router takes 2 passes to cut through the 9 mm plywood.

Cutting the tabs that hold the parts gives me something to do while the machine works.

Digging a quarter inch wide slot into plywood makes a lot of dust very quickly. In this slow motion view you can see the tool pump out the chips and fling them around. I generally keep my dust collection boot in place to contain the mess.

The short, thin tabs are easily cut to remove the parts.

The coaming lip is cut from 4mm okoume.

My plan is to mount the coaming on a sill that will serve as the coaming recess. The perimeter gets punched full of holes for sewing on the skin.

After the frames have all been cut out, I round over all the edges that won’t be touching a stringer. This will make the frames smoother to touch and help protect the edges.

Last spring I rough cut a bunch of cypress. I’ll be using this material for the stringers. First I clean up one face.

I haven’t got a big enough shop to keep all my tools in a place where I can deal with full length strips, so I need to move the required tools in and out for each task.

The side stringers are 1-1/2” wide by 3/8” so I rip one blank to width then split it in half.

I’m making all the other stringers 3/4" wide, so I just rip the rest of the stringers in half.

All the stringers are run through my thickness plane to bring them down to the correct dimension.

The CNC machine left a 1/8” radius on the inner corners of the frame stringer slots. Rounding over the corners of the stringers lets them fit easily in the slots, and eliminates the sharp edge inside the kayak.

Step 2: Assemble the Coaming

My idea for the coaming is stacked plywood pieces including

a bottom sill to transition from the skin to the coaming, then thin plywood spacers topped with a lip to hold a spray skirt.

I let the ShopBot drill a bunch of stitch holes around the perimeter of the sill. I now want to ease the edges of those holes so the thread doesn’t get cut when I sew on the seam. I use a countersink on the drill press to chamfer the holes.

There are a bunch of holes, especially when I’m doing both sides, but thanks to the wonders of fast forward, it doesn’t take too long.

The CNC cut coaming parts all get assembled with epoxy. I add a little fumed silica to it to thicken it up so I can apply a fairly heavy coating to the sill and underside of the lip.

I then add more silica and some wood flour to make an even thick glue. The wood flour just turns it brown so it matches the plywood better.

Each spacer gets smeared with the epoxy schmutz before being situated in place on the sill. I had divided the spacers into quarters to be more efficient with the plywood. There are two layers of spacers here, then the top is the lip.

With the parts roughly in place I start clamping the stack together. The parts need a little adjusting to make sure they are all lined up with the interior edge of the hole.

One inviolate rule of boat building is there is no such thing as too many clamps. Lots of clamps assure the seam is tight without waves between pressure points.

There was a little gap where the CNC ate a part. I filled it with the schmutz.

After the epoxy cures all the clamps come off.

The oscillating drum sander makes pretty quick work of cleaning up the glue squeeze out. I’m careful not to pause in one spot. Stopping can create a low spot which may catch the drum again, digging the spot even deeper. By keeping the part moving on the sand I get a nice fair interior surface.

The drum sander can not reach the coaming side next to the knee hooks. Instead I have to come in with a rasp to clean off the epoxy blobs.

I want to eliminate most of the sharp edges on around the cockpit. First I use an 1/8” radius round over to ease the outer perimeter of the sill and the edges of the knee hooks.

Then I switch over to a half inch diameter to round off the top and bottom edges of the coaming.

Step 3: Test Fitting the Frame

I made up a quick drawing showing the locations of each

frame. I’m marking those locations on the strongback I use for my strip built kayaks. Because the kayak tapers towards the ends, the reference location of a frame is the face closest to nearest end.

Risers screwed to cleats will be used to hold the frames at the correct location along the length. I’m only using the risers to establish the lengthwise position. I’ll let the stringers define the frame height and centering.

A couple clamps loosely hold the frames to the risers.

The first stringers are what substitute for my sheer or gunwales. These are 1-1/2 inch tall by 3/8 inch thick. They run perfectly parallel to the waterline. As such they serve to establish the height of each frame.

In the cockpit area I have spacers between some frames. They are connected together with a mortice and tenon. I did not dog-bone the mortices with the shopbot, so I use a rasp to quickly round over the corners of the tenons so they will fit correctly.

This is really just a test fit, so I am using zip-ties to hold the stringers instead of lashing. I wanted to see how things went together before I finalized some to the fits.

The stem frames include a little birds mouth to accept the ends of the keel. Holding the keel in place next to the frame, I mark and cut it to fit.

With the sheer and keel stringers installed, the frame positions are now defined and I can start adding the rest of the stringers to create the shape of the hull.

The microBootlegger Sport design features the same kind of transitioning chine of my Petrel Play. At the stern the chine is quite hard, but in front of the cockpit it becomes more rounded. I will accomplish this by blending one stringer into another midway along the length.

This first chine stringer extends from the stern to a point along the keel line where it blends into the keel stringer.

At the point where the chine stringer meets the keel stringer I create a tapered cut to match the intersection of the two pieces.

This fit will need some refining but I first install the matching chine stringer on the other side.

Once both chines are installed, I can make a better cut and touch it up with a block plane.

Beginning roughly at the cockpit a second stringer splits off from the chine stringer. This is gradually tapered to blend smoothly into the chine and then spreads away as it approaches the bow.

I started by clamping the cockpit end to the existing chine stringer. Then I traced the edge of the chine on to the stringer.

I brought this to the band saw to cut off the excess and cleaned it up with a block plane.

Using the plane, I rounded over the new edge.

Now all the bottom stringers are installed. I checked the alignment looking for wonky shapes, but it looks pretty good without any adjustment.

I started installing some of the top stringers while the frame was still upside down. When it became hard to reach things I flipped the whole deal over.

The center fore-deck stringer ends at the front of the coaming. I transferred the slope of the coaming to the stringer and planed it to match.

I’m not a fan of being poke in the stomach with sharp sticks, so I trimmed off the end of the stringer appropriately.

The coaming and the deck side stringer want to occupy the same volume of space. So, I marked where they hit including the slope of the coaming. I then whittled out the bits of stringer causing the problems.

The upper fore-deck stringer also intersects the coaming recess, so I marked the angle and cut off the ends.

The other end of the stringer needs to be planed to lie flat against the stem frame.

Now I went back and trimmed the ends of all the remaining stringers.

The next day I disassembled everything.

This project is really an experiment. I have some ideas on how to do a skin-on-frame that is a little different and I just want to check them out. I’ve already made some new frames and added a couple parts.

Although zip-tying it all together, then taking it all apart again adds some un-necessary steps, it allowed me to check how things were working and think about how to proceed.

For example, should I add holes for lashing, and if so, where should they go. Looking at it put together helped figure this all out.

I decided to add lashing holes, at least in some places. So I used an 1/8” drill to punch the holes.

These holes were also countersunk slightly to protect the lashing.

I added some more holes to the coaming piece to help lash it down.

While I had the frame disassembled I took the opportunity to give all the parts a protective coat of oil. I could do it after the frames done, but I have found that the oil can dissolve the wax coating on the lashing sinew a bit. This can loosen up the knots.

Step 4: Lashing the Frame

A few of the frame pieces need to be assembled. Here the stem frame is fitted to the last sectional frame.

I use a waxed nylon floss called artificial sinew which is an untwisted thread that has a thin cross section and holds a knot well.

The sinew is tied to the part and then threaded at least 3 times through each of the holes and pulled tight after every pass. The wax helps hold it tight after pulling.

I tie a couple knots around the bundled sinew to secure the ends.

The assembled frames are clamped back to the risers to hold them in their approximate location.

At this point I don’t sweat the height, it is enough to just get their lengthwise spacing established.

The frames include some longitudinals for mounting the foot braces. I’m inserting some stainless steel t-knots so the foot braces can be bolted in place. I whack them in with a hammer to set the spikes.

It is easier to mount the braces now while the bolt holes are easily accessible.

These rails are assembled to adjacent frames in the same way I lashed together the stems.

The final assembly are the frames around the seat which include rails to eventually secure a backrest.

The wide main stringers can now be placed. These run perfectly horizontal and serve to define the height of all the forms. I hold them in place with a few temporary zip ties.

The ends of the main stringers will be lashed into a hole in the end frame.

A figure eight knot in the end of the sinew serves as a stopper. I thread the sinew through a couple hole and then tie the knotted end around long end with an over hand knot.

When I pull this loop tight, the overhand knot works its way up the sinew until it snugs up against the stopper knot.

The goal is to lace the sinew through the holes enough times that the parts are securely held together. Just one loop is usually not enough, but as you pull more loops through the holes, it acts like a block and tackle, providing more and more mechanical advantage until the parts are tight.

I like to get at least three passes between each hole.

This lashing was doing a fine job of pulling the stringer in from either side, but pulling the sinew tighter had the tendency to push the end form to the right. I needed some lashing to pull the stem back in.

The addition of a small hole through both stringers allowed me to get tension to keep the stem snug against the ends of the stringers.

After lashing both ends, I brought in the keel stringer.

Using holes through the keel avoids creating lumps along the bottom which may cause abrasion. I situated these holes so the lashing pulls the keel tightly into the hook on the stem.

After securing the bow, I lashed in a few of the frames along the length before moving to the stern.

Learning from the bow, I started with some lashings to hold the stringers together, then went directly to a pattern that pulled the frame tightly against the ends of the stringers.

Shooting holes in on either side of each frame did a good job of pulling the keel tightly into the slot. While the sinew is quite thin it would leave a bump if it passed over the keel. Because the bottom is the mostly likely point for the kayak to hit stuff, avoiding the bump should reduce abrasion.

Getting all the frames lashed to the main stringers and the keel starts to lock the shape in place. Later bending in of the additional stringers will add some force that may try to curve the frame. Hogging, where the ends of a boat droop down is common with skin on frame kayaks. Lashing these frames now should avoid hogging later.

But once these three stringers are secured, I could start right in with the rest.

I didn’t bother lacing the sinew through holes in any stringer beyond the keel because I figured any bumps in the finished surface elsewhere were not a big deal.

There are a lot of lashings needed, but once you get into the flow of it, they don’t take long.

With these side stringers, I’m just trying to get the end tucked in tight to the stem frame.

The chine stringer runs from the stern up to the keel just short of the bow, then a secondary stringer extends from the bow frame to about half way back where it blends in with the chine.

I need to lash the forward end of the chine stringer into the keel stringer. The gradual taper makes it tricky as the lashing wants to slip forward. Since the spacing is closer up forward, this loosens up the lashings.

I originally just tried wrapping the sinew tightly around the stringers from the narrower end back. But the wraps just slid down the taper. I solved this problem by drilling a hole through all the stringers and starting my wraps there. This prevented slippage and eliminated the bumps along the keel.

With the bottom stringers all installed, I flipped the frame over, and started with the foredeck stringer.

Like the keel, I positioned the holes so the lashing pulls the stringer in tightly against the stem notch.

I then thread some sinew through the hole and tie a figure eight knot as a stopper.

A figure eight has the end wrap over the sinew then circle around behind then the end goes down through the loop.

The overhand knot loops around other leg, down under the sinew and down through the loop.

When you pull it all tight the overhand knot slides up to the stopper knot and then pulls the loop snug against the stopper.

By forming a V shape with the lashing I create the ability to pull it even tighter when I’m done.

The last pass before the knot comes out at the top of the V. I thread the sinew under the lashing and make a couple wraps around the needle.

When I pull this snug, it closes up the bottom of the V, cinching all the threads even tighter.

Another pass under the lashing and wraps around the needles lock this knot in place.

As added insurance, I add a figure eight stopper knot on the end. I use the tip of the needle to pull it as close to the lashing as possible.

These lashings are really robust. Since the lightweight frame is bound to flex a little bit any stiffly glued connection between the stringers and the frame would likely crack and break. The sinew lashing is flexible and resilient allowing movement without breaking.

Gluing the low surface area joint would be problematic. Most waterproof adheasives, such as epoxy are stiff and relatively brittle. The edge grain of the plywood frames forms weak joints. As a result this lashing will be substantially more durable than glue.

The aft end of the fore deck stringer gets lashed to the forward cockpit frame and then the coaming ring will be lashed to it.

I ended up shooting a few extra holes in the coaming ring to provide lashing point between the ring and the frames. The ring lies on top of the frames and gets lashed down directly to the frames.

The front of the coaming ring is lashed directly to the ends of the stringers, tying the whole system together as one unit.

This whole process of lashing together the frame is kind of fun. While there are quite a few lashing point, it is nothing compared to wiring together a stitch and glue kayak or fitting strips on a strip built design.

It is quiet and relaxing and provides quick, satisfying results.

Step 5: Sewing the Skin

My friend Dave came by to see how I’m doing it and give me a

hand. Dave is one of my frequent paddling companions. He is also very skilled with a surfski in rough conditions as well as a experienced boat builder.

The cloth I’m using for the skin is a polyester filter fabric. This is left over material I purchased years ago for an earlier project from Dyson Baidarka & Company. Looking back at my records, it is a 14 ounce cloth.

I had just enough to cover the frame.

We unrolled it and centered it on the frame then pinned one side in place. I slipped a lath under the skin as a cutting surface.

In the past I used a soldering iron with a modified tip to cut the cloth. I now have a nice hot knife that glides through the material. A melted edge like this is really nice as it binds the edge a bit to keep it from unravelling.

After trimming one side, I fold it back and cut the other side. The trim line is about one inch from the centerline. This should give me enough material to sew the seam.

The seam stitching method I use I learned from Robert Morris’ book “Building Skin on Frame Boats”. I start by running two lengths of parachute cord down the length of the seam. Here I looped the cord around the coaming and tied it tightly back to the stem form.

Here is Dave working on sewing the bow seam. The twine is threaded through the cloth, under the parachute cord then through the cloth again before going through the other side in a similar manner.

Then another needle runs another length of twine back approximately through the same holes from the other side.

The bow has a stringer running directly down the centerline. This helped keep the seam straight. Dave stuck push pins through the para-cord into the stringer to keep the cord tight and centered.

With this cloth, a stitch every centimeter or half inch seems to do a good job. We are trying to get the cloth as tight as we can at this point, but it doesn’t need to be drum tight.

While Dave worked on the bow, I got started on the stern. I did not have a stringer running down the center line so it was a little hard to keep the seam straight. In the future I will probably insert a temporary batten as a guide.

I found that pulling the thread taught along the seam helped pull it down under the para-cord. I moved the spring clamp after each stitch to hold the tension.

This method of sewing the seam is quite quick. I like how the parachute cord reinforces the edge providing a secure point for pull the cloth tight. There is no fear of over pulling and ripping the fabric.

The results are very clean and neat, especially where Dave was following the deck stringer.

At the stern where there was no stringer, I found I got the best results when I pulled the para-cord very tight and secured it with some push pins. By working my way down, pulling the thread tight, I eventually started getting straighter results.

I also eventually started running out of thread. So I finished off the ends by pushing the needles through just one side of the fabric and tying a knot between the threads.

When I started the new length of thread I step back a few stitches and overlapped for a while to insure a secure junction.

We kept with this seam technique until we got to the stem. I did not want the large raise seam cutting into the water. I trimmed off the para cord even with the end of the stem and trimmed the fabric a bit over size.

Working down the stem, I stitched one side to the other just using the thread to gather together the excess cloth. I was still using two needles but I would do a few stitches with one, going one direction and then follow with the other going the other direction.

I kept this up all the way down to the bottom of the stem, gathering together the last little pucker with a few more stitches.

I wasn’t completely satisfied with this seam so on the bow, I left a little more excess when I trimmed the fabric.

This extra let me fold the ends over and stitch through the fold, tucking the excess inside the seam.

I then proceeded like before, stitching around the edges with two needles. I finished off the bottom by returning part way back up the stem.

I think this system of folding in the edges before sewing made a cleaner looking seam.

I made a mistake when I first cut the fabric to size. There was a little corner next to the cockpit that the cloth did not cover. To fix this I needed to cut a patch. I wanted it to look symmetrical so I cut a matching corner out of the other side.

I then cut a triangular patch to fit.

The parachute cord was not part of the patch, so I cut it off.

I used a similar stitch to the bow, folding the edges down and sewing between the two sides.

While I would rather I didn’t have to patch it. The fix was quick and easy to do.

I added a para-cord edge to attach the skin to the coaming perimeter.

I’m sorry I didn’t get any close ups, but I just sewed up through the holes and doubled up fabric, then around the para-cord and back down through the same hole. This process was just repeated all the way around the perimeter.

The fabric is rolled around the cord and then sewn down through the holes in the coaming apron.

I thread up through a hole, through the doubled up fabric, around the para-cord and back down through the same hole, then move to the next hole.

Over, up, around and down, over, up, around, and down. If I needed an extra hole, I shot one in. I trimmed as I went to be sure I didn’t cut too much off.

It’s a little awkward reaching in under the coaming to thread the needle up through the hole. I found a pair of forceps handy to hold the thread tight in the prior hole while I was threading into the next hole.

The thread I’m using a braided polyester fishing line. It was nice stuff to work with. It didn’t have much tendency to tangle, and was relatively easy on the hands to pull tight.

I am really pleased with this technique for sewing the skin to the coaming. It is very straightforward, not requiring anything fancy. As long as I kept the skin rolled tightly around the parachute cord, it made a very clean edge.

Now for the magic of polyester fabric. I want the skin drum tight. While it is possible to do this with sewing techniques, it takes some work. At this point the fabric is finger tight, with most of the slack removed.

A very hot iron pressed firmly against the cloth makes it shrink. While polyester is not the strongest fabric choice, this ability to heat shrink is awesome. Once shrunk tight the fabric will not loosen and sag.

Step 6: Painting and Outfitting

I decided on a two tone paint job. I thought it would look

nice to have the topsides a cream color and the bottom a pale green. I want to make the transitions right at the waterline.

I’m using the main stringer as a reference as it should be parallel with the waterline. According to my calculations, if I make the transition between colors about 2-inches below the bottom of the main stringer, it should be about perfect.

Taping a pencil to a scrap piece of the main stringer creates a gauge that is just about 2-inches. Running the top of the gauge along the bottom edge of the main string I make a series of marks.

My plan was to run masking tape along the marks to define the bottom edge. But I tried everything and nothing would stick to the raw fabric.

I ended up just masking off the coaming area to keep paint off the wood and only on the cloth.

Without the masking tape at the waterline, I instead used my marks as a guide to brush paint along the bottom edge. I wanted to go a little beyond so I could overlap with the bottom color.

Once I had the edge defined, I used a roller to cover the long wide surfaces.

Up around the coaming I used a brush to work paint into the fabric and the stitches.

This 14-ounce cloth is fairly thick and has quite a bit of texture. While I am not trying to fill the weave or make a smooth surface, I do want the paint to soak deeply into the cloth.

This stuff absorbs a lot of paint. I bought a quart of each color of the best exterior latex the home center had and ended up using all of it to apply two coats over everything.

After the topside dried, I flipped the boat over. Now with the paint on the surface, masking tape did stick, so I re-marked the waterline and taped it off. The green tape stuck better, the blue gave me a wider tape line.

I kept coming back over the same area while the paint was wet. This gave the fabric a chance to soak up some paint. I don’t think the paint, or anything truly bonds well to the polyester material, but after soaking into the weave the paint created a good mechanical bond with the cloth.

Again, Latex house paint isn’t necessarily the most durable option. There are some two-part urethanes that are wicked solid, but Latex is very affordable, and easy to get in any colors to suite your taste, and they are probably tough enough for most uses, and should you scratch it up touch-ups are easy.

I modified my standard seat so I could adapt it to the skin on frame. The CNC machine chews through minicel foam like nobody’s business. I start with a roughing pass using a 1/2-inch endmill and then come back over with a ball nose on the finishing pass. I made the step-over wide because its foam, It’s not like I’m going to sanding it later.

After thinking about it for a while, I decided I wanted some slats under the seats. A pair of butt bumps sticking out of the bottom when you paddle isn’t too big a deal, but who needs the bruises if you paddle over a log.

This lashing would have been easier to accomplish before installing the skin, and in the future I will likely incorporate some mortices in the frame to accept the tabs, but that is the whole reason for making a prototype, figuring out how to do it better next time.

The seat wedges tightly between the frames and stringers. I may glue it in eventually, but it seems fine like it is.

The backrest has elastic straps behind to help hold it up. I loop these elastics up and around the next frame back.

I decided to go with fairly minimal decklines. I measured out three spots 6-inches apart into the center of the main stringer. I used an awl to open up a hole in the fabric. A screw through a finish washer and a loop of webbing should make a reasonably secure attachment point for shock cord.

Notice that somewhere off camera I added some automotive vinyl striping tape along the waterline.

I had envisioned the forward straps on the backrest being bolted into the solid section of the side frames, unfortunately, I didn’t put the solid part in the right place. Instead I just ran a loop of webbing up and around the next frame forward.

The shock cord is threaded through these loops, back and forth to either side. It requires a bunch of sliding and pulling to get enough cord through all the loops.

My standard system for linking the shock cord back together is a couple hog rings. These stainless steel bits of wire are crimped around the cord and then hidden under a length of heat shrink tubing.

With the heat shrink shrunk, the kayak is done. As of this point I have not yet put it in the water, but I will say that it was a fun project. I gave myself 3 weeks between the time I started designing it and finishing it up. I was able to do that easily, with plenty of time for other stuff.

Step 7: Launching

No kayak is truly complete until it has been put in the water and used. Since it is winter and there is ice on my river I have not had a chance for a full sea trial, but some open water appeared for a few days so I was able to get the kayak wet.

A lot of people have been asking if I will be offering plans or kits. That is a goal, but this build was just a proof of concept. The largest task in offering plans and kits is not building the boat, but writing the instructions.

I need to test the design, modify it as needed, build another and document it with photos and more in-depth video, and then write a comprehensive manual. Writing takes longer than building. Unfortunately, I cannot estimate when I will have that project done. I’ll post a notice here when its ready.

If you are interested, do let me know in the comments. Obviously, a lot of interest would be motivation for me to work faster. I think it’s a great project, fun and easy, and a cool boat when you’re done.

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    2 years ago

    Thank you for all of this amazing information! I'm considering a SOF Kayak project of my own and am wondering if you have more details on the cloth you used to see if I could source something similar locally (Southern California). My research only has led me to vinyl/pvc laminated polyester cloth and I don't believe this is what you're using. Any help is much appreciated!


    3 years ago

    I’d really love to be able to buy the plans for this


    3 years ago

    I'd be interested in the plans as well! :)


    3 years ago on Step 7

    This looks great. I would like to build one using Paulownia as the wood. It is readily available in Australia as a plantation timber. Can I buy the plans from you. This was a prototype two years ago, so I thought you might have saleable plans by now. If so , can they be in an electronic format that can be put into a CNCmachine?

    neil mccormack
    Brisbane, A


    3 years ago

    That looks great - nice build! What was the final weight? Have you had any issues with the skin leaking? I've never seen a build just using latex paint on the skin!


    Reply 3 years ago

    I've been paddling the boat for more than a year now. No problems with leaks yet.

    I won't try to say latex paint is the best coating, but it is cheap, easy to use and adequate. If it starts leaking apply more paint.

    A 2-part urethane such as Corey's Goop is undoubtably more durable, but expensive and tricky to apply.

    Forn Man
    Forn Man

    5 years ago

    I'd love to buy the offsets. Any chance you'd consider giving them the Tom Yost treatment?


    5 years ago

    Absolutely beautiful! I made a skin-on-frame more than ten years ago and since i moved from the seaside eight years ago i miss it terrible. When i saw you wonderful ible i thought maybe i should find a lake nearby and build a new one.


    Reply 5 years ago

    Thank you. It was a fun project. Most of my boat building projects take much longer. This was fun because it was quick and easy. I really like the results as well.


    5 years ago

    WOW, what a wealth of information. Thank you for this!


    Reply 5 years ago

    Thank you. I hope you find it useful.


    Reply 5 years ago

    I'm glad you like it. Thanks.