Clinker (lapstrake) construction builds a boat shell-first: attach the garboard plank to the keel on each side, shape each next plank to overlap the one below by 2-3 cm, drill through the overlap and rivet it every 8-10 cm with copper nails clenched over a rove, then add ribs, gunwale and thwarts. A 4.5 m hull with 8 planks a side has 14 laps of about 4.5 m, which at 8-10 cm spacing is roughly 630 to 790 rivets.
Part of Canoe & Rowing Boat Construction
Clinker, or lapstrake, is the Viking-tradition way of building a hull from overlapping planks that are fastened through their overlap.
The Shell Makes Its Own Shape, Which Is Why It Suits A Solo Builder
In clinker the planks themselves define the hull’s shape and are fair together, and ribs are added only afterwards to stiffen the result. That is the carrier’s reason for calling it forgiving: a plank that is slightly off still lies against its neighbour, because the lap lets it adjust. The overlapping planks are strong together, since each stiffens the one below. The carrier also notes that no caulking is needed because the overlap is sealed by the fasteners and by the swelling of the wet wood, and that the growing shell holds its own shape, which suits a builder working alone.
The method is not careless. The hull’s symmetry depends on the first planks being fitted evenly, and the lap’s bevel must change gradually along the length or the planks do not lie flat.
What You Need
- Backbone and planks as in Keel, Stems & Backbone and Planking Methods
- Copper nails and roves (small washers) in matching sizes; iron rusts and loosens, as the carrier warns in the maintenance notes
- A helper, or a heavy block (a dolly) to hold against the nail head while the rivet is peened
- A drill, nippers and a hammer
- Temporary moulds (cross-section templates) if you want help holding the planks to the intended shape
Method: Plank And Rivet
Step 1: Fit the garboard, one on each side, attached to the keel.
Step 2: Fit the next plank with a 2-3 cm lap against the one below, spiled to the gap (see Planking Methods).
Step 3: Drill through both planks in the lap.
Step 4: Rivet. Drive the copper nail from outside, place the rove over its point inside, hold a dolly against the head, cut the nail slightly proud of the rove, and peen it over. Space rivets every 8-10 cm along the lap.
Step 5: Continue upward, alternating sides and checking symmetry constantly.
Step 6: When all planks are on, steam-bend and fit the ribs (see Ribs & Frames), then gunwale, thwarts and knee-braces.
Worked Example: Counting Rivets
Suppose the hull has 8 planks a side, so 7 laps a side and 14 in all, each about 4.5 m long (the hull’s length; real laps run slightly longer). Rivets at 8 cm: 450 ÷ 8 = 56 per lap, and 14 × 56 = 784. At 10 cm: 450 ÷ 10 = 45 per lap, and 14 × 45 = 630. The planning range is therefore 630 to 790, about 700 on a mid-range choice, before adding the ends at stems and keel. Each is a hole to drill and a nail to cut, so spacing is a real labour decision.
Common Mistakes
- Rivets too close to the plank edge — the wood splits along the grain; drill pilot holes before driving.
- A gap in the lap — it weeps; if it persists after the planks swell, rivet closer.
- Iron nails — they rust and lose their grip, unlike copper.
- Bevelling the lap unevenly — see Planking Methods.
Safety
Cut nail ends and peening
Cut copper nail ends are sharp; a piece cut under tension can fly. Wear eye protection when cutting and peening, keep the helper’s hand off the dolly’s face, and sand over the rivet heads before anyone rows.
What’s Next
- Learn next: Caulking & Waterproofing — what a clinker hull still needs
- Combine with: Carvel (Smooth Hull) — the other route