DESIGN AND BOAT BUILDING, 2012
This pram was built in the traditional Norwegian manner: upright and by eye. Instead of bending its planking to a set of predetermined "station molds," the planks are lapped to one another and riveted in place. White oak frames, "knees," and a belt of steam-bent pine called the "inwale" provide structural reinforcement. The shape, considerably cambered and rockered, is imparted simply by the cut of each plank. To avoid splitting the brittle kiln-dried pine stock, I attended closely to the wood's pliancy, bending it to the point of resistance but no further. I used a set of ash shores to prop the boat in place from above and below, and to ensure its symmetry. Ash, denser than pine, was rigid enough to maintain the boat's shape while flexible enough to absorb any sudden blows of planks springing free from the temporary clamps.
The boat has no cotton and tar caulking, yet has remained water tight. I achieved this in a few ways. First, by hollowing the face of each lapped plank along its beveled length, I gave each lap two mating surfaces rather than one. I fit the white oak frames tightly to the planking to reduce the strain on the copper rivets and to prevent their loosening from wear. Lastly, I fit the raking forward and aft transoms using multiple templates to more closely approximate the complex angles at which the planks terminate.
The structure of the boat is efficient. Despite its dense white oak rib cage, the pram is lightweight and lithe in the water. There are no floor timbers and its thwarts bear directly on frames and planks rather than on additional quarter knees. At the same time, the boat's design makes it stable in the water. Its flat bottom gives the pram high "initial stability," suitable for ferrying passengers and larger loads without rocking. The high longitudinal shear provides "secondary stability," allowing the pram to cut through choppy seas without shipping much water.
Credits: Scott Peterson; Matthew Dirr