How to Frame a Rob Roy Kayak

Monfort’s ultralight construction technique is very forgiving for home builders and requires only simple tools and a limited workspace. The construction materials are inexpensive, and there’s no need for the elaborate forms, complex processes, sanding and fairing epoxy, or vast workspaces associated with other boat building methods.

Although I’m an experienced boat builder, even I prefer starting with plans. The kayak I built for this article is a Rob Roy 14 cruising kayak for lakes and rivers, from plans copyrighted by Geodesic AiroLITE Boat Designs, a company operated by Monfort’s grandson. The blueprints arrived with an instruction manual, specifications, and technical details. A pattern sheet includes the various components portrayed full-sized to trace onto your plywood — stems, coamings, knees, deck beams, decks, and stations. I always inspect plans to become thoroughly familiar with all the terms and components, and highlight elements in different colors to make them easier to read. I also use an inexpensive architect’s scale rule with imperial units to measure components on the plans. The rule is like a miniature yardstick, and the plans I used are drawn up at 1-1/2 inches to the foot. As with most proprietary boat plans, you’ll need to purchase your own set to build a kayak like this one. But this article will take you through the general techniques that’ll apply to most skin-on-frame kayaks.

This project took about 120 hours to complete. The finished boat weighs about 36 pounds, and its capacity is 300 pounds. The length overall is 13 feet, 10-1/4 inches, and the beam is 27 inches. The keel has a 2-1/2-inch rocker. Here are my detailed instructions, along with some advice, on building a kayak.

Tools and Materials

• Table saw
• Power planer
• Block plane
• Cordless drill with bit set
• Utility knife
• Back-cutting Japanese saw
• Saber or band saw
• Framing and combination squares
• Architect’s scale rule
• Clamps, both spring and sliding bar
• Level
• Safety wire or zip ties
• Power sander
• Staple gun
• Tack puller
• Home clothes iron
• Marine plywood; for stems, decks, bulkheads, knees, deck beams, and butt blocks
• Construction-grade plywood for stations
• 9-ounce polyester fiber fabric, enough to overhang the kayak by at least 6 inches at each end, and more on the sides
• 16-foot spruce, Douglas fir, pine, or eastern white cedar, clear and straight-grained, for stringers, gunwales, rub rails, and keelson. You can also use scarf joints to connect shorter pieces.
• Cedar or pine for floor boards
• Mahogany, ash, or mahogany marine plywood for the coamings
• Oak, ash, or elm, clear and straight-grained, for ribs
• 16-foot 1×8 softwood, straight-grained, for strongback (4)
• Scrap wood for cleats and braces to hold parts in place and aid in clamping
• Epoxy, both quickset and thick construction with a long working time
• Spar urethane
• 1-inch #6 brass or bronze screws
• 3/8-inch Monel or stainless-steel staples

Terms and Parts Glossary

• Bulkheads: Pieces that remain in the boat to provide support for the stringers.
• Butt blocks: Pieces glued below the decking to hold the pieces together.
• Coamings: Angled pieces that shed water from the open cockpit.
• Deck: The upper portion of the kayak, which encloses the hull and has an opening in which the kayaker sits.
• Deck beams: Pieces that form the curvature of the deck and support the deck stringers.
• Gunwales: The sturdy pieces that run lengthwise along the uppermost edges of the kayak, forming the edges of the deck.
• Hull: The portion of the kayak that displaces water; in this case, made of polyester fabric coated in resin, but traditionally made of stitched sealskins.
• Keelson: The backbone of the vessel, which runs down the center of the bottom.
• Knees: Shaped pieces that support the deck in gaps between bulkheads and deck beams.
• Ribs: Thin, steam-bent pieces that provide support to the stringers from inside the hull.
• Rub rails: Pieces that protect the uppermost edges of the hull and cover the joint between the deck and hull covering.
• Stations: Temporary pieces used to outline the shape of the kayak. Think of a sliced loaf of sourdough bread. The slices will be different sizes and shapes throughout the loaf. The kayak stations are like selected slices along the length of the loaf, with the other slices removed.
• Stems: The tips of the kayak.
• Stringers: Thin strips of wood that form the overall shape of the kayak by running lengthwise from stem to stem. These are attached to the deck beams and bulkheads, and temporarily to the stations during construction.
• Strongback: A long, square-cross-sectioned beam made of flat panels on which the kayak is built, which provides stability during construction.

Build the Strongback

Screw the four 16-foot softwood boards together along the long sides to make a long, hollow box. Check with a level to make sure the box doesn’t twist, bow, or sag. Anchor the strongback to a table or set of sawhorses with screws to keep it from shifting. Establish a centerline along the length of the box with a tautly stretched string, and pencil it in. Establish reference station locations every foot along the centerline. Use a square to mark the stations crosswise on the box, and install cleats to anchor the stations at 2-foot intervals. The strongback box is also a great place to store all your long rails and stringers until they’re used.

Use the Pattern and Cut Pieces

The great thing about building a kayak from existing plans is that the blueprints will contain a sheet of full-sized patterns for the station molds, bulkheads, deck beams, knees, stems, decks, and coaming. Only one side of the station molds and bulkheads will be shown, as the pattern can be flipped across the centerline to create the full piece. The easiest way to use the patterns is to place thin cardboard or poster stock under the plans, with a layer of carbon paper in between. Then, you can trace the pattern pieces using a stylus, an empty ballpoint pen, or even a dowel pointed in a pencil sharpener. Be sure to include the gunwale (top of deck beam) mark on the stations and stems. Cut the transferred pattern pieces out with scissors.

You’ll notice that some of the station pieces have notches and some don’t. The notched pieces are the permanent bulkheads that’ll remain in the boat. Use marine plywood for these. The unnotched pieces are the temporary stations that’ll be removed after the ribs have been installed, and you can use construction-grade plywood for them as long as it’s flat.

To cut the stations and bulkheads, draw a centerline on the plywood and align the cardboard pattern on it. Trace around the pattern, and then flip it, align it with the centerline and the ends of the outline you just drew, and draw the other side. You’ll notice that the stations have one flat side. This will rest on the strongback while you build the hull. The notched bulkheads have the deck curve drawn in. Cut a flat side above this curve for now, so that they’ll also rest flat on the strongback.

Cut the stringers, gunwales, rub rails, and keelson as continuous lengths if possible, or join shorter pieces with scarf joints for strength and flexibility.

Follow the notes in “Tools and Materials” above for which woods to cut the remaining pieces from.

Prepare Stations

Set the stations and bulkheads in place on the strongback, butting them against the cleats. Make sure the centerlines match and that they’re square relative to the strongback. Screw them to the cleats.

Install Stems, Keelson, and Gunwales

Note: The bow and stern stems are different from one another. The tops of both are cut to lay exactly flat on the strongback, at the point on the centerline shown on the plans. Make little wooden cleats to hold the tops of the stems in place while you work.

Draw a centerline onto the keelson and bend it over the stations and the bulkheads, aligning it with the notches on the bulkheads and the marked centerlines on the stations. After checking that the stations and bulkheads are still vertically square to the strongback, glue the keelson to the bulkhead notches and anchor it to the temporary plywood stations with soft “safety wire” or zip ties. Bore small holes into the stations to anchor the wire. Bring the keelson to the flat bottoms of the stems, and, when the keelson lands properly on the flat of the stem at the centerline, use a wood screw and glue to fasten the two together.

Next, install the gunwales. Like the keelson, insert the gunwales into the notches on the bulkheads and around the stations at the marked locations. Carefully mark the bevels where the gunwales contact the stems, and cut them carefully with a thin Japanese saw. When they fit perfectly, screw and glue the gunwales to the stem and bulkhead notches. Temporarily wire them to the stations as you did the keelson.

Install the Stringers

Install the stringers, five per side, in much the same fashion as the gunwales, although their locations are only firmly located by the notches at the bulkheads. Eyeball their spacing along the stations and at the stems to make a smooth, fair line, mirroring them across the keelson.

A Gentle Ribbing

With the stringers installed, you can bend the ribs, which you’ll rip from straight-grained stock with no defects to 3/16-by-1/2-inch strips, well-sanded with rounded edges. You’ll need to steam them to make them flexible enough to bend into shape.

Steam bending is easy to do, but it does require organization and preparation, because you’ll only have moments to bend the ribs after you remove them from the steam box. Begin by marking out the locations where the ribs will land and be fastened. Space the ribs 8 inches apart, measuring square from the stations.

Make sure you have a couple dozen spring clamps on hand for the bending process, and a good pair of leather gloves to protect your hands. It’s always a good idea to find a flexible piece of wood or plastic on which to practice your techniques before firing up the steamer and working with your project wood, and a helper will be invaluable to make the best use of your brief working time.

The secret to the operation is to have plenty of roiling hot steam, and cook the ribs for the right length of time. The formula is roughly half an hour per 1/2 inch of the thinnest dimension, which means you’ll need to steam the ribs for this project for 11 to 12 minutes. To avoid overcooking, don’t put more than three ribs in the steamer at one time.

You can make a simple steam box with a 4-inch-diameter plastic sewer pipe that’s a bit longer than your ribs. Drill holes through the pipe into which dowels can be inserted that span the pipe. The dowels will form a rack that allows the steam to circulate. Drill a few extra holes to allow old steam to escape. Use standard plumbing fixtures to cap the ends and provide an entrance for the steamer hose. An electric wallpaper steamer makes an effective and fireproof steam generator.

Remember, your working time for bending and fastening the ribs to the stringers and gunwales is short. Attach the first rib in the center of the boat. Wearing your gloves, pull a rib out of the steam box, limber it up by overbending it, and then insert it under the stringer-covered hull and above the strongback, and pull the rib up to meet the stringers at the locations you marked earlier. Clamp it into place and let it cool. Some builders will install screws from the keelson and gunwales into the rib at this point. You can also use electrical wire ties to temporarily affix the rib to the stringers.

Stagger the ribs to avoid distorting the hull stringers as you install them. The plans I worked from suggested that I move two stations forward and repeat the operation. Then, move two stations aft of the original rib, and so on. Keep an eye on the stringers for any distortion. If you see any, simply remove the clamps and reset the problem rib. My plans also included a short section of rib bent in just behind station two for the floorboards to land on.

When all the ribs have been bent in, they can be fixed into place with thickened epoxy or lashed into place. After the epoxy has set, the tops of the ribs can be trimmed flush with the gunwales.

Deck Beams, Knees, and Stringers

While the boat is still upside down, use a Japanese saw to cut the correct curve of the bulkheads from the drawn square tops. Do this in one smooth cut, so you can use the strongback and the attached waste pieces of the bulkheads to create a cradle for the kayak when it’s turned upright. Remove the screws holding the stems and stations to their cleats, and lift the hull off the strongback.

Use a few lengths of split, closed-cell water pipe insulation from the hardware store to pad the bulkhead scrap by sliding them down over the cut edges. You now have a dandy padded cradle to support the righted kayak.

The deck and its stringers will be supported by the tops of the bulkheads, the deck beams, and the knees. Only some of the deck beams were shown on the pattern sheet I was working from, because the angle of the deck crown and the intersections between the ends of the deck beams and the gunwales remain the same all the way down the kayak; the deck beams simply become narrower to suit the narrowing deck. The deck beams and knees are cut from marine plywood for durability, fastened to the deck stringers with triangular cleats, and fastened to the hull with thickened epoxy or lashings (as the ribs were fastened).

Next, insert the knees, anchoring them to the hull and the deck beams.

After the deck beams and knees have been fit and fastened, it’s time for the three deck stringers. One runs down the center of the decks both fore and aft, and the other two are spaced equidistant between the center and the gunwales. To get the location of the stringers, spring them over the deck beams at their approximate locations and hold them with your spring clamps. Measure, and, more importantly, eyeball them for a smooth curve. Mark where they land on each deck beam. Cut notches into the plywood deck beams like the bulkhead notches that anchor the gunwales. Insert the stringers and glue them into place. Trim off any extra length.

Glue small wedges to the sides of the stems just below the gunwales and above the entrance of the stringers, to support a hole for a rope “lifting toggle,” which will make carrying and moving your kayak much easier. After the wedges are glued in place, bore through them to create the toggle hole. Now’s a good time to varnish the frame and all sides of the floorboards while everything is open and accessible.

Install the Floor and Decking

Though it seems out of order, you’ll install the floorboards at this point, while you have better access for your drill and screwdriver.

Only two of the plywood deck pieces on my kayak are patterned; these are the scalloped panels that are mounted forward of the cockpit. The other pieces are simple rectangles, and their dimensions are given on the plans. The deck pieces are a bit persnickety to fit, so it’s worth making plywood patterns from construction-grade plywood first, to get your pieces exactly right before you cut into the marine plywood. Connect the decking pieces with marine plywood butt blocks and triangular cleats mounted underneath the deck with epoxy. Varnish the under deck before attaching it to the frame with epoxy.

Cover the Hull

Although this phase might seem intimidating, it really is pretty straightforward, and much easier than working with sealskins. You’ll need a clean spot for spreading out the polyester fabric, sharp scissors, a sharp utility knife, fast-setting epoxy, a staple gun, 3/8-inch Monel or stainless-steel staples, a tack puller, and a home clothes iron.

Invert the kayak again, and drape the polyester fabric diagonally over it, with a corner at each stem. Roughly trim the fabric so it easily covers the hull to the gunwales, leaving at least a few inches at every edge to grab for stretching. The offcuts will be used to cover the decks.

A note about the quickset epoxy: Wear gloves, be sure to use the right proportions, mix it for 60 seconds, and only make small batches that can be rapidly applied.

You’ll be anchoring one side of the fabric to and around the gunwale and deck at one side with epoxy and staples; stretching the fabric skin across the frame of the hull, and anchoring it with epoxy and staples to the opposite gunwale and deck. Mark a 6-inch overlap line on the decks, and protect the decking beyond that line with a strip of masking tape.

Try to get the polyester fabric as tight as possible, but don’t worry if it doesn’t initially end up drum-tight — that’s what the clothes iron is for. If you want to practice your technique, do a dry run with staples alone, and wrap a bit of polyester fabric around a dowel to provide more purchase for pulling it tight. Start at the midpoint of the hull, and slowly work your way toward the ends, gluing with epoxy, stapling, and stretching in small sections until you’re close enough to the stems that you can no longer stretch the material smoothly. Trim the excess material, leaving 4 to 6 inches extra.

A Skintight Finish

Now’s the time to fire up the iron. Set it to approximately 250 degrees Fahrenheit, which is typically the medium setting on a home iron. You’ll move the iron over the fabric skin in a sweeping motion, gently removing the wrinkles as you go. Work alongside deep ripples to draw the fabric up gradually for a smooth finish. Again, start amidships and work outward to the stems.

When you’ve tightened the fabric up to where you stopped stapling and gluing, slit it from the free end along the centerline to about 1 inch short of where the stem curvature begins. Wrap the fabric around the stems to get a rough idea of where it’ll sit, and then trim one side of the split cloth so it overlaps the face of the stem by 3/4 inch. Cut notches into this piece to allow it to wrap around the ends of the stringers, and then glue and staple it down. Lap the second piece over the first and glue them together. After the epoxy cures, shrink the fabric onto the hull. If you included toggle wedges, pierce the fabric over the bored holes.

From a piece of scrap, cut two “doubler” strips of polyester fabric on the bias (diagonally), each 2-1/2 inches wide and long enough to cover the stems. These strips will overlap and protect the covered stems, and the bias cut will allow them to stretch smoothly around the curves of the keel as it rises to the stems. Glue these into place with epoxy, and, once again, open the toggle hole.

Cover the Decks

Flip the kayak upright, and trim the excess hull fabric from the gunwales.

Lay out one of the fabric offcuts, and roughly cut it to overlap the forward half of the kayak by a few inches in every direction. The fabric will be glued to the top of the deck with epoxy, and then run over the gunwales, glued, and stapled.

Draw a line 1 inch in from, and following the edges of, the decks (both the scalloped forward and straight aft decks), and use masking tape to protect the decking beyond the drawn line. Apply epoxy to the exposed plywood edge of the forward deck, align the fabric, and press it into the epoxy. After the deck glue has cured, smooth the polyester fabric over the sides of the gunwales, glue it, and staple it. Shrink the polyester fabric with the iron until it’s drum-tight. Carefully trim the polyester fabric along the plywood deck line with a utility knife. Peel the masking tape away carefully to avoid lifting the polyester fabric.

Repeat the operation for the aft deck. Then, trim the gunwale overlaps to 1/2 inch, and then cover the overlapped fabric with the 1/2-inch rub rails, fastening them every 8 inches with #6 wood screws.

All ‘Coaming’ Together

Only the forward part of the coamings is shown on my pattern sheet, but the side pieces are the same shape cut 41 inches long. The coamings will be “welded” to the deck with thick epoxy.

Use the scale rule to measure the location of the forward coamings and the angle at which they intersect at the centerline of the deck. Draw their locations in with pencil and use masking tape to protect the deck around that line. The coamings are tipped forward a bit by the angle at which their ends meet at the centerline of the deck. Make what might be a tricky clamping job easier by making a couple of L-shaped clamping blocks with the rail angle cut into them. Clamp one end of each block to the deck, and the other to the rail. Use quickset epoxy to join the forward coamings to each other and to the deck. Then, run a bead of thickened epoxy (like a welding bead) along both sides of the rails and the centerline joint.

After the forward coamings have been set, the side coamings can be fit, epoxied, and “welded” into place. Lightly sand the coamings and rub rails.

A Fine Finish

Varnish will not only sport up the look of your woodwork, but also waterproof your polyester fabric. Use a foam brush to apply several coats of spar urethane with UV resistance.

Pass short lengths of sturdy rope through the holes in the stems, and then through holes bored in wooden toggles, or short lengths of pipe with the cut surfaces sanded smooth, and knot the ends. These handles will make your kayak much easier to handle, and will also give you tie-down points for transporting it on a vehicle. Add a seat, whether handmade or purchased, and buy or make a double-bladed paddle; a 9-foot one will suit this craft’s measurements well. Keep a comfortable life jacket — one you’ll actually use — with your kayak.

Seriously consider flotation bags that fit under the decks; the Rob Roy style of kayak, while perfectly seaworthy, rides low — and the whole hull is accessible to fill with water in rough conditions. Cone-shaped versions are just the ticket, because they don’t take up much room. To hold everything down, you can add a deck-mounted shock cord kit.

Then, head out for that remote pond with a camera, lunch, and a fishing rod! John MacGregor would approve.

Greg Rössel grew up on the waters of New York Harbor and in the boatyards of Staten Island. He lives in Maine, where he’s specialized in small wooden boats for nearly 40 years, from construction and repair to museum documentation and drawing up plans. He’s written hundreds of articles and several books on wooden boats, including Building Small Boats (Wooden Boat Publications).