Preparing Materials

Mo 'Poxy's Chesapeake 17 Kayak Construction

Chesapeake 17

This blog is a photo essay of building a wooden kayak. It is a stitch and glue boat made from mahogany marine plywood known as okoume.

I build my boats from scratch, not kits, using published plans and raw materials. This kayak model is the Chesapeake 17, designed by Chesapeake Light Craft. 

Preparing Materials

First, I rough-cut the side and bottom panel pieces out of 4mm okoume plywood. Then, I cut the scarphs and the glue scarph joints to create a rough-cut version of the 17-foot long side and bottom panels.

I obtain my mahogany marine plywood from Edensaw Woods. Okoume is a surprisingly soft wood and 4mm is very thin. I often cut this plywood with a utility knife and a metal straight edge.

However, for long cuts along 8-foot sheets, I use a circular saw with a high quality carbide tipped fine-cut blade. Whenever possible, I stack 2 or more pieces of plywood and make a single cut, especially when the cut pieces are identical shapes. If you are only building one kayak, you could succeed with just a utility knife and without a circular saw.

Once the pieces are rough cut, I use a John Henry Scarphing Jig, mounted on a Makita power planer. The scarphing jig is very economically priced but the power planer is very expensive. This system makes easy cutting of perfect scarphs. However, it is probably not economical unless you will make many scarph cuts in your life, or if you need the power planer for many other uses. Due to the thin and soft plywood, scarphing can also be accomplished with a sander or a hand plane.

John Henry scarphing jig on Makita power planer

I use System 3 epoxy for gluing. Since the scarph surface is large end-grain surface in soft porous wood, I pre-wet the scarf surface with unthickened epoxy, to saturate the end-grain. Then I use thickened epoxy for the glue in the joint. For gluing or laminating, I thicken my epoxy with silica powder. When I need thicker epoxy for fairing or fillets, I thicken with both silica powder and wood flour. Silica powder and wood flour are available from System 3. Silica powder is somewhat expensive and wood flour is cheap. You can thicken with wood flour alone. Many beautiful boats have been built with just wood flour as a thickener for epoxy.

Okoume panels scarphed together

Wood flour and silica powder

WHENEVER I USE THE TERM "EPOXY" I AM REFERRING TO EPOXY RESIN MIXED WITH THE PROPER AMOUNT OF HARDENER.

I final-cut the two side and the two bottom panel pieces, to the precise dimensions specified in the plans.

The plans provide very precise dimensions for cutting the side and bottom panels. I layout the dimensions according to the plans. This results in dots every foot along the panels. Then I connect the dots with a thin 8-foot piece of clear wood. Such a piece of long thin wood is often called a "batten". I use nails, weights and clamps to fit the supple batten to the dots, then mark with a pencil.

The curves of these panels are gentle enough to cut with a circular saw. I cut them proud ("proud" means just beyond the final limits) then I sand the cuts to the exact pencil lines.

Rather than measure, layout, mark, cut and sand every panel of every boat that I build, I created patterns (the red painted pieces) out of construction grade 1/2-inch plywood. Then I use a router with a pattern cutting bit to cut the actual panels. That way, additional panels for future boats can be pattern-cut without repeating the measurement and layout.

Cut panels and templates

I ripped 1x stock for the sheer clamps. Sheer clamps are wood strips that lie under the deck at the edge. They connect the deck to the side panels. These are just 3/4 or 5/8 by 1-inch to 1½-inch strips. I've made sheer clamps from continuous 18-foot strips. In this photo, I made them by scarf-joining several shorter pieces into 18-foot strips

Ripping sheer clamps

Cutting the coaming layers: the coaming is the lip around the cockpit. It is built up bay laminating several layers in-place for a strong cold-molded piece. These layers are cut from the large piece of 4mm okoume plywood that is left after rough-cutting the side and bottom panels. This is another step where I created and used patterns rather than measure and layout every single piece

Cut coaming layers

Cutting the hatch covers: These are cut from the small 4mm okoume plywood remains left after cutting the coaming layers. By modifying the rough cut dimensions to use less plywood, I have wood left over to make larger hatch covers than those specified in the plans. The resulting larger hatch openings are greatly appreciated when loading and unloading gear.

Once again, I use patterns to cut these. However, instead of a flat pattern-cutting bit, I use a radius bit in my router. That way, these hatch covers have a perfect rounded edge for aesthetics

Hatch covers cut from patterms

Ripping stock for deck beam layers: these strips are cut from the small 4mm okoume plywood remains that are left after final-cutting the side and bottom panels. Nuthin' fancy here.

Deck beam layers

Ripping stock for rub rails: Rub rails are strips along the top of the side panels and edge of the deck that protect this corner from damage. I rip 3/4 clear oak into 3/4 x ¼ pieces. Then I round the outer two corners. I paint them then store them outside for weeks so that they gain moisture and grow longer, before they are installed. Otherwise, after installation they will gain moisture and grow longer, becoming an unsightly mess.

Oak rubrails