Popular Mechanics (South Africa)
25 STEPS TO BUILDING YOUR OWN STITCH-AND-GLUE BOAT
1 | Procure a set of plans, or scaled drawings of what you’re going to create. Devlin creates plans for hundreds of DIYers, detailing the keel shapes and all the materials you’ll need.
2 | If your boat is longer than 8 feet (2.4 m), edge-join the marine plywood panels end to end (called scarfing). If using a kit, the kit manufacturer will provide waveto-keyhole type indexing to the ends of the panels that will allow them to be joined.
3 | If you have a CNC router, use it to cut the panels to size (there are usually 5 to 8 for a small, simple boat). Skip to step 14.
4 | If you don’t have access to a CNC router, draw lines across the width of the panel at right angles to the long edge of the plywood, 1 foot (30 cm) apart.
5 | Make marks at the bisects at each line, as shown on the plans, then hammer small brad-type nails (‘fence posts’) partially into the plywood at each of those intersections.
6 | Draw smooth curves between these fence posts using a flexible wooden batten to span smoothly between each of the fence posts. When complete, remove the nails.
7 | Saw the panels out, leaving about ⅛ inch (3 mm) extra plywood overhang so you can see the line you drew.
8 | Take both pieces and use a block plane to even them out so they’re symmetrical, smoothing the cutting lines out to the pencil line marks made previously.
9 | Do this for all of the panels of the boat, which together will make up the entire hull.
10 | Use a block plane to knock 45° bevels on half the thickness of the panel, on the inside surfaces (where it will mate with another panel).
11 | Scribe a stitch line, usually the thickness of the plywood plus ⅛ inch (3 mm), and predrill small holes as marked on the designs. This works well on the bottom panels.
12 | For larger boats (those above 4.5 m long), stitch upside down – it eliminates having to roll the boat over another time. A small boat can be stitched right-side up, because rolling one of these is much easier.
13 | For larger boats, set up the bulkheads, or athwartships (sideways) and longitudinal (lengthways) structures that add structural strength and help define the architectural space of the boat. For small boats, use spreaders, which are small battens that open the top of the boat to the designed width, to stretch out the shear of the boat.
14 | Start with the two bottom panels laid one over the other (like a closed book) at the bow end and stitch the first two panels together at their keel edges. This process is similar to sewing two pieces of fabric together, but instead of a needle, you can feed the wire through the holes with your hands. It should be tight enough to keep the peels sealed together.
15 | Open the two halves of the bottom panels like opening the pages of a book and fit them over the bulkheads upside down. For small boats, use spreaders to maintain the correct shape.
16 | Repeat this process with each panel, stitching one side and then the other, from bow to stern. When all the panels are in place and the stitches are clamping the panels together into a boat shape, stitch the transom to the ends of the panels. For small boats, add spreaders to open up the top of the boat to the planned size.
17 | Start epoxy tabbing, which is like tack welding, putting epoxy and fibreglass tabs between the wire sutures, on the interior of the hull.
18 | Once the tabs have cured solid, at least 24 hours but maybe more in humid climates, you can pull out all the wire stitches and lightly sand over the tabs to smooth things out.
19 | Finish fibreglassing the interior seams of the boat. Set several layers of fibreglass tape in epoxy resin over the top. Then fibreglass the exterior plywood panel seams.
20 | Once the hull is to the designed thickness and all seams between the panels are taped with epoxy and fibreglass cloth layers, sheath the entire exterior of the boat with epoxy and fiberglass cloth. Some builders use a final layer of peel ply to control the resin-tocloth ratio and eliminate air bubbles.
21 | Finish fibreglassing the seams of the interior of the boat, starting with narrow tapes up to the final width designated on the plans.
22 | Sand the boat inside and out to help smooth the edges and overlaps of the fibreglassing. Reseal with epoxy resin rolled and brushed over the hull as smoothly as possible.
23 | Sand and seal one final time and roll the boat over.
24 | Install the interior, such as seats, hardware, and the engine.
25 | Paint the entire boat, inside and out. Opaque paint offers the best UV protection, which is important to shield the boat from the sun’s reflection off the water.