Its been about a week since I put up a posting, but expect a flurry of them now. Later today we have the launching of the Bengali boat. Earlier this week we took the Bengali boatbuilders to the Seto Inland Sea Museum, probably Japan’s oldest maritime collection. The museum is located high on a peninsula with a panoramic view of the Inland Sea. The collection is fascinating, focusing on the rich traditions of fishing and seagoing trade of this part of Japan. The lines drawing we are using to build our boat comes from the museum’s collection.
There is an excellent mockup of a boat shop inside the museum, with a partially built boat inside. Next to the boat is a plank being bent, using the same method we used (note the stone used for a weight), right down to the tin containers for fireboxes. A series of models shows the steps in building a small boat, as well as an interesting method for bending planks when it is not possible to prop them overhead, or the boatbuilder has large clamps.
Another display shows the steps in sawing between planks to finish the seam, and the use of chisels to cut mortises and pilot nail holes.
One final detail captivated me: in Japanese boats often athwartship beams are tenoned through the hull, shouldered on the inside. Often the tenons are cut flush and covered with copper (what we will do on our boat) but in larger boats the tenons are exposed slightly and wedged. I have never seen anything like the wedging of the tenons on one large boat at the museum. Its really a key, dovetailed in cross section and tapering from top to bottom. The timber on top is the rubrail, which locks the key in place.
One of the things that has struck me about Japanese boatbuilding is the degree to which during the construction of a boat the builder makes changes that deviate from the original drawing. All my teachers who used drawings worked from a 1/10th scale image. Scaling from that size is inaccurate, yet the drawings were just a starting point for them; during construction issues would come up with the material and changes would be made on the spot. The process of sawing to fit planks can also remove more than 1/4” of material. As a result the final boat could deviate considerably from the measurements first laid down on the wood.
Photos here show my apprentice, Takumi Suzuki, fitting the kajiki with our handsaw, and then cutting the nail holes with a special chisel. Finally, there are some shots of him driving nails.
In the West boats are generally built around moulds that define the shape exactly. If the builder is careful in building their mould from the lofting the boat should conform exactly to the plans. But Western boats are built of thinner and narrower planks for a given size than Japanese boats, and are much easier to force into a particular shape. The Japanese builder has to struggle to bend thick, wide planking, and it doesn’t always work out the way one might expect.
In our boat I tried to keep the angle of the kajiki consistent with my lofted lines, but at the forward station (called the habadokoro, or “width place”) I just felt we were forcing the planks too much, so I let them stand a bit tall. Our kajiki are probably 3/8” higher at the chine than designed.
When we hung the second kajiki yesterday I tried to keep the planks at the same angle, but at the aft habadokoro the starboard kajiki stayed a bit low after we nailed it. I tried propping it higher but decided against putting too much strain on the plank and risking cracking it. I will try raising one plank and dropping the other.
Again, I saw all my teachers basically abandon their drawings fairly early in the process, opting for sound construction techniques and overcoming unexpected issues. In this respect Japanese boatbuilding is very improvisational.
In this part of Japan the props we use to hold parts of the boat in place are called tsuzu. Elsewhere in Japan my teachers also called them tsukai bo or tsuppari. Whatever you call them, they are absolutely integral to traditional boatbuilding in Japan. The shop itself is also a critical tool. All the shops I have worked in had heavy overhead beams, all to bear the pressure of the myriad props used in building.
Our structure is built of 90mm x 90mm beams (almost exactly the same as an American 4 x 4), entirely bolted together. However, when we started to prop the kajiki (garboard plank) in place, we not only moved the boat but we deformed the top beams and at one point lifted the entire structure! So we have tried to prop against the bottom beams rather than the floor, and I clamped two additional beams overhead. Nevertheless the whole arrangement is dicey, but we’ll make it, and in the future we will build this a bit differently.
At the stern I used a pipe clamp, which has been very handy. Ordinarily Japanese boatbuilders use few, if any, clamps in this situation. I have seen them use rope and a Spanish windlass (twisting the rope tight with a wooden bar). I have attached one photo from my second apprenticeship in 2001 showing the props we used to hang the kajiki on the bekabune, a boat I built at the Urayasu Museum with Mr. Nobuji Udagawa. You can even see props pushing against props, something we too are doing here in Takamatsu.