Nasu had a large collection of hand tools, particularly saws and planes. The only power tools we used were a circular saw and electric plane. We did all the final finishing of surfaces with handplanes. Nasu used an axe for rough shaping and for chopping out plugs. Other critical tools are his kasugai (metal staples, or dogs), of which he had several dozen. We used these instead of modern clamps to pull parts together, align planks, and to secure boards tightly while we glued and nailed them. We also weighted the bottom with large stones to hold it in place, and used posts to brace the planks against the ceiling of the workshop. When planking the sides we depended on many more props to hold planks at the proper angles.
Nasu’s most interesting tool was a special chisel for drilling nail holes called a momigiri or, more commonly, moji. He was surprised when I told him I had never seen another one in Japan, where boatbuilders typically use a special chisel called a tsubanomi to cut holes for boat nails. Part of this difference can be attributed to the nails because ubune are built with nails that have a square shank, and the moji cuts a round, tapered hole. In the rest of Japan, a boat nail is made from flat steel and the tsubanomi cuts a rectangular hole.
–Douglas Brooks, excerpt from “The Last Boatbuilder of the Nagara River,” from Issue Twelve