First Butt Joint and Her Length.

Solo mariner Sven Yrvind bends and clamps the initial plywood hull sheets in his Västervik workshop, constructing a test boat for a high-latitude cruiser. Maneuvering long sheets of plywood without assistance presents immediate physical hurdles inside the shop.

Working alone requires heavy mechanical tension on each panel. As Sven notes, it is “tricky to do it just by one man,” relying on clamps to draw the stiff plywood against the frame bit by bit. When drawing a tight bend, the force required can cause slips. Sven admits, “I put the clamp close then put all my force on it. And then what happened? I fell down.” Even after taking a knock during the fall, he recovers to continue bending the timber.

Scribing and Fairing the Hull Lines

With the side panel drawn close, Sven inspects the contact tolerances along the hull. Measuring the gap, he finds roughly 3 cm touching forward and 2 cm of contact aft. To achieve an even profile, he marks the overlap, trims away the excess 3 cm, and fair the curve.

Using a flexible wooden batten, Sven springs a fair line across the length of the wood to establish a clean contour. After scribing the curvature, he cuts the profile using a German hand saw. Because the hull design features identical left and starboard sides, completing the initial curve allows him to copy the exact template directly to the opposite panel.

Mirroring Panels and Panel Lofting Math

Because the hull rests upside down on the workshop floor, Sven takes care when labeling the mirrored pieces. Setting the opposite side on the inverted jig, he notes that “negative starboard must be port” and marks the panel accordingly before tracing the final outline.

Using standard 122 cm plywood sheets, Sven finds that his calculated curves fit neatly across the stock with minimal waste. As he explains, “two sheets on each side. But, in fact, this was just pure luck,” with the panels overlapping cleanly along the hull stations.

Mathematical scaling produced a similar match along the bottom. Applying a scaling factor of 0.913 to his lines, Sven arrived at a bottom beam dimension of 610 mm. When doubled across the centerline, the total width equals exactly 122 cm—matching standard sheet widths without requiring extra cuts.

Measuring Hull Length and Making the First Butt Joint

With the side panels lofted, Sven stretches his measuring tape along the centerline to verify the hull dimensions. The longitudinal measurement comes to 4,647 mm, with an additional 6 cm margin on the dimension side.

Sven brings the side sections together, reporting that the “first pieces of plywood are joined. Butt joint. Just to make it simple.” Here at the bow, he decides to “leave a gap here in the front, you know, to make it give a bit more volume” when meeting oncoming waves at sea. Once the bow and stern framing are secured, the build will advance to installing the bottom planking and applying protective glass fiber cloth over the experimental hull.

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