Building a Tenma-Zukuri Chabune (伝間造茶船) – Part 2

In my last post, I discussed the building of a tenma-zukuri chabune from the Funakagami, and I stated that I was working on my model, but didn’t actually talk about building the model. The fact is that I wasn’t sure about what scale to build it at, given that a 1/10-scale model would end up being a little over two feet long, and I’m running low on space to display or store my models. So, I started a 1/20-scale model to see how I’d feel about the smaller scale.

I began by making a temporary internal frame. This would allow me to build the shiki, or bottom, and add the miyoshi, or stem, and the todate, or transom, at the proper angles. The same goes for the tana, or hull planks.

The longitudinal member of the framework is shaped directly from a copy of my plan drawing. The cross pieces are located at positions of the funabari, or beams, and are shaped according to my drawings.

If you look at the photo of the framework, you may notice that the cross pieces don’t extend all the way to the bottom. My thought was that I could go ahead and add the floor beams to the shiki, Then, notches were cut in the longitudinal frame piece so that it would fit nicely over the beams. The cross pieces would then rest on top of the floor beams.

I chose hinoki, actually Port Orford cedar in this case, for the building material on the smaller model. I used sugi, or Japanese cedar, on larger models as this is the material the actual boat would have been made from. However, at the smaller scale, Hinoki would be much easier to work with and should look better with its finer grain pattern. I started by using an analine dye mixture on the wood to give it a darker, more natural finish, though hinoki will darken slightly over time.

I didn’t take any photos of the intermediate steps as I was really just experimenting and didn’t know if I would continue with a 1/20-scale model or not. In fact, I went ahead and started working on the shiki for a larger 1/10-scale model. I may eventually build a model in that scale, but I’m going to see how the smaller model turns out.

At this scale, I decided not to simulate the mortises for the edge fastened planks as I’ve done on the 1/10-scale wasen models I’ve built. There are plenty of obvious mortises to be dealt with later in the koberi, or rub rails, and opportunities to simulate various fastenings. But, the trapezoidal mortises cut for edge-fastening the planks together would be plugged and already difficult to see on a 1/10-scale model, so I’m electing not to try to cut them into the wood at this scale.

One thing here is that I chose not to use a building board in construction. Looking back, I think this was a mistake, as it was difficult to build the model and keep the miyoshi, or cutwater, straight. In the future, unless I can master a technique for attaching planking without twisting the shiki or miyoshi, I’m going to have to make a mount for the frame to fit onto a baseboard to hold everything more securely.

As for the planking, the hinoki was easy to bend without the need for heat, requiring just a bit of dampening. I used Original Titebond wood glue for construction. This turned out to be a good choice, as it is easy to de-bond with the use of water, and I had some alignment issues regarding the stem and transom.

During the attaching and shaping of the hull planking, I used small clamps to hold the framework in place. Once the planks were shaped and glued into place, the framework also served as a guide to help me shave down the top edge of the planks to the right height.

After that, I cut some hinoki for the upper funabari, or beams, and began cutting the notches in the hull for them. I ended up making these on the wide side. The funakagami illustration shows these beams much thinner, but the wider beams are easier to fit, so I went with them instead here. While cutting the ends of the funabari to fit, I notched the hull planking at the same time. For this part of the process, I really took my time to get the shape right so that the end of the funabari would a nice perfect fit.

The ends of the funabari will be covered by the koberi, or rub rail. Then, there is a cap rail called uwakoberi, which will fit atop the hull planking, effectively locking the funabari into place. Of course, it’s quite possible that these were secured in a different manner that is simply not detailed in these paintings, but based on what I’ve learned about wasen construction, this seems very reasonable.

In any case, I have yet to add the tatematsu, which are vertical posts that connect the upper and lower funabari together, so that will be next.

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