Plank a boat from the bottom upward, starting with the garboard plank beside the keel, shaping each plank to fit the gap left by the one below it; clinker overlaps each plank on its neighbour and is riveted through the overlap, while carvel butts planks edge to edge over frames and caulks the seams. With a 3 cm lap a 15 cm clinker board covers only 12 cm of hull, so the same hull in clinker consumes 25% more board width than in carvel.
Part of Canoe & Rowing Boat Construction
Planking is the stage of boat building in which boards are fitted one at a time from the keel to the gunwale to form the hull shell.
The Gap You Are Filling Is Never The Shape Of A Straight Board
Hull planks curve in two ways: they bend to follow the hull’s shape and they twist and taper toward the ends. The lowest plank, the garboard, is fitted first and the others follow in order. Each new plank must fit against the one below it, whose edge was itself cut to a curve, so a straight board must be marked from the actual gap before it is cut. That marking is called spiling: hold a thin batten or a strip of wood against the line to be followed, transfer the distances from it at several stations along the hull to the board, and cut along the curve you draw.
Clinker and carvel differ at the edge. In clinker the lower plank’s top edge is bevelled so the next plank lies flat against it with a 2-3 cm lap; in carvel the edges are cut with a slight bevel so that the seam is tight on the inside and open slightly on the outside to take caulking.
What You Need
- Boards long enough to run bow to stern, or joined with scarfs
- A flexible batten for spiling and a pencil
- Clamps (the carrier’s advice: you never have enough; improvise with wedges and a stick twisted in a rope loop)
- Plane and drawknife to bevel the edges
- Fasteners and drilling tools (see Drill and Auger)
Method: Plank Both Sides Evenly
Step 1: Fit the garboard on one side, then on the other, so the hull does not twist toward one side.
Step 2: Spile each following plank, cut it slightly full, plane to the line, and offer it up.
Step 3: Clamp and check the fit before drilling: the plank edge should follow the line of the one below with no light showing through.
Step 4: Fasten — rivets through the lap in clinker (see Clinker (Lapstrake)), nails or screws to the frames in carvel (see Carvel (Smooth Hull)).
Step 5: Alternate sides at each plank to keep the hull symmetrical, and measure the diagonals every second plank.
Worked Example: The Board-Width Budget
Assume the hull’s side from keel to gunwale measures 0.9 m (an assumed shape; measure yours). In carvel a plank of 12 cm covers 12 cm, so 0.9 ÷ 0.12 = 7.5, i.e. 8 planks per side, using 8 × 0.12 = 0.96 m of board width. In clinker with a 3 cm lap (the upper end of the carrier’s 2-3 cm) a 15 cm board covers 15 − 3 = 12 cm, so the count is again 8, but each plank must be cut from a 15 cm board: 8 × 0.15 = 1.20 m of board width per side. The ratio is 1.20 ÷ 0.96 = 1.25: clinker takes 25% more board width. Wide boards cup and shrink more than narrow ones, so on a tight timber budget the number of boards, not their width, is the lever.
Common Mistakes
- Planking one side only first — the hull twists out of line.
- Skipping the spiling — a plank cut from a straight line leaves wedge-shaped gaps.
- Letting the lap edges run out of bevel — in clinker, a flat lap against a curved plank leaves a gap.
- Fastening before checking — you cannot draw a plank back once the rivets are set.
Safety
Clamped planks store energy
A plank bent to fit a hull springs back if a clamp slips, and a steamed plank is hot. Wear gloves, keep your face away from the plank’s end when releasing a clamp, and read Ribs & Frames before steaming.
What’s Next
- Learn next: Ribs & Frames — the skeleton inside the shell
- Combine with: Clinker vs Carvel Construction — the choice behind the process