Fitting and Fastening

Now its all the little stuff, for the most part, to finish the boat.  Though the stem and rub rails are pretty major elements.  But today I fit and installed the stern deck, fastened the bulkheads through the boat's bottom, and trimmed the plank edges.

But first I removed the props that have been holding the hull since we bent the bottom to shape.  

At the stern I followed Murakami san's layout for the two-piece stern deck, which has a slight angle between the two pieces (just to make it harder, I guess).

I took some measurements and cut the first piece out roughly.  Because the boat has tumblehome (at the stern the side planks slope inward at the top).  I could raise the piece up inside the hull until it got tight to the sides, below the line as you can see.

Holding my pen tight to the planking I scribed the shape of the sides and the angle on the edge.  I then cut to my line, knowing that the scribed lines should still be a bit large.

Then I did something Murakami san depends heavily on, kigoroshi, or pounding the plank edges with a round-faced hammer.  If you look closely what I did here was pound the entire surface except for the top edge (which will be visible) and the forward edge (which has to fit tight to the next piece).  

Then I fit it again, much closer this time.  But having pounded most of the end grain faces there is just a narrow edge actually touching the plank.  This made it much, much easier to plane a little bit away.

It was still tight but I just tapped it up with my hammer.  Again, with the reduced surface area of the end grain the small edge that touches easily crushes.  The result is really a perfect fit.  You are not cutting to fit but wedging material together.

In order to fit the back edge of the deck to the face of the transom I ran the saw through a joint a few times.

Then I nailed the deck around three sides from the outside.  I had pre-drilled from the inside, then ran the bit back into the deck once it was in place (it stayed there nice and solid, wedged in place).  I inserted some common nails just to keep it in place while I chiseled holes for the boat nails.

And I did the same through the transom and into the deck.  Drilling out first from the inside at the precise location and angle, I then run the drill from outside into the deck edge.  I let the drill follow the hole through the transom so I know the angle is right.  Drilling these small pilot holes is not something my teachers did, but its a huge help, because as you chisel with the tsubanomi if you keep a relaxed grip the tool will follow the hole.  Needless to say this would be a very difficult hole to chisel through the back of the transom, hit the deck edge, and travel through its center.  Murakami san did it, but he's built over a hundred more of these boats than I have...

I fit the second part of the deck the same way.  Note it meets the first at a very slight angle.  Like Murakami san, I edge-nailed to forward part of the deck to the back.

Then I rolled the boat on its side, just about the limit of my strength to lift one side.

And I put fastenings through the bottom and into the three bulkheads.

I put a little bit of goop around each nail just before hammering it home.  The are countersunk slightly in small mortises and Murakami san squirts in some kind of silicone to cover all exterior nail heads.

Beams and Bulkheads

Today was the day to fasten the bulkheads and fit and install the beams.  Mostly I followed Murakami san's methods with a few deviations.

First thing today I nailed the bulkheads through the side planking with long, small-headed nails (the same type used to edge-fasten the planks).  Then I began installing the beams in the mortises.  I start by sliding the beam in (from right to left in this photo).  The shouldered tenon is clearly visible on the right, note the angled cutout on the left.  This required me to relieve the top of the mortise on the left side, slightly, so the end of the beam can be lifted.

Once the beam is inserted far enough I can drop the right side down inside the boat.

Then I drive the beam back through the mortise on the right until the shoulder fetches up against the inside of the hull.

I use the cutout from the left side, carefully cutting it to length to fit inside the boat, and insert it in the beam.  It was a tight fit which required I drive it with a hammer.

The other side is shouldered tight to the planking.

And the cutout is glued in place on the left side, locking the beam in.  Murakami leaves a little sliver of wood on the left side of the cutout which fits in the angled slot cut earlier, further locking the whole thing in place, but he has to swing the cutout into the space and can't get a fit to the planking as tight as this.  I figure the glue will hold the piece from moving so I opted for the tighter fitting joint.

The forward beam goes in the same way, but from the opposite side.  This is how Murakami san does it.

Then I had to cut hinoki wedges for the through tenons.  I used the museum's workshop's bandsaw.

I have written about Mr. Shoichi Nagatsu, a saw sharpener in Kyoto.  I used his custom-made saw to cut off my tenons.  He cuts these gullets in a specially designed Japanese saw.  The uninterrupted teeth to the right are for starting the cut.

Murakami only used one wedge per tenon, biasing the mortise to one side.  I decided to go a more traditional route and use two.  Basically two tenons allowed me to close any sloppiness in my mortises that appeared on either side of the tenon.  Here the tenon is wedged...

...and cut flush.  Hard to see here but a cut with Nagagatsu's saw leaves a surface so smooth it almost feels planed.

View of boat with bulkheads and beams installed.

I have my two days off now.  When I come back Tuesday I will remove the props.

I also trimmed the planks aft of the transom.

Old Stories

Mr. Murakami, whose boat I am replicating, has been sending us material ever since he was here helping me with the fire bending workshop.  He sent a paddle for the boat, some hardware, and now four plank drawings that he and his father used to build several types of fishing boats.  Most of these drawings date from the 1960s.  On the back of three are calendars showing how many days he and his father worked on each boat.  Later in a phone conversation with the museum’s researcher, he said he was paid just ten days labor to build an isobune like I am building now.  He could build them in ten or eleven days.  Basically he had to in order to make a decent wage.  This further explains his very innovative use of power tools to speed up the boatbuilding process.  

The slashes represent full days, numbers represent hours of a partial day, circles represent holidays.  The boat above took 13-1/2 days to build.  It's over twenty-two feet long.  Often such drawings are missing crucial information - the boatbuilder's secrets - and only the builder can use them.  This secrecy sometimes extended to apprentices as well, who were forced to steal their master's dimensions.  Because Murakami apprenticed with his father there was no secrecy, hence his drawings are complete.

Meanwhile, I started to prepare material for bulkheads and beams.  These are wide offcuts of 2" thick cedar being cut and planed for three bulkheads, two of which form a live well in this type of fishing boat.

I got out my hinoki (cypress) and milled up beams using the circular saw and a handsaw, avoiding the sapwood.

Two caregivers brought three women in their nineties to the museum.  They were among the most engaging visitors I have had, full of questions and comments (all very supportive of my work and research).  One woman finally said her grandfather had worked as either a carpenter or architect (she said both) building houses in San Francisco.  Later I found them sitting at the table looking through my books.  

First I fit the bulkheads.  The largest beams sit on top of them, shouldered and tenoned through the hull and wedged from the outside.

I noticed one of my beams fell right on a nail, something I should have been thinking about when I laid out the nail locations for the planks...  I moved the beam a bit to miss the fastening.

I drilled holes at the corners and used a Japanese keyhole saw to rough cut the opening.

Murakami cut these quickly and then finished the mortises by pounding the edges, literally crushing them to his line.  I don't have the tool he used so I chiseled mine.  Of course his method is faster.

The beam at the bow requires a tricky compound angle.  I lay the beam on top of the planking and scribe the sides by laying the square tight against the beam and flat to the planking.

Then I measure the height of the mortise by measuring the distance across the beam at the plank angle.

I lay out those dimensions then do the same inside the boat.

While chiseling I check for flatness.

The beam is slightly tapered, so its pounded in...

...until it fetches up tight.  

The museum's temple carpenter stops by two or three times a day, looking in at what I am doing and then leaving without a word.  This afternoon when he saw this beam he finally spoke, saying, "I can't do that."  Having seen his work I am quite sure he could figure it out.  Actually my Middlebury College boatbuilding students have really enjoyed the challenge of laying out beams on our boats the last two years.  I basically give them no instructions and leave it to them to figure it out.

Final beam aft just forward of the transom.  

Pounded from one side.

In place with the ends slotted for wedges.

Today an elderly boatbuilder from Kobe stopped by, clutching a newspaper article about my project.  He talked about building wooden boats in Kobe, and later building steel boats in Osaka.  He said he built boats as small as ten feet, but it was unclear how large his wooden boats were, though he said he used boat nails a foot long!  We talked about various differences between this boat (from northern Japan) and the boats he built locally.  He pointed out the knots in my port planking and said that was good, that knots indicated strong wood.  I've never heard that before.  

He said at the end of his career there were very few orders, so competition among boatbuilders was fierce.  He said he finally retired after the Kobe earthquake in the mid-1990s.  He is 86 and when I asked him his name he said he didn’t believe one should show one’s name or photo; he said these things shouldn’t be made public until after one’s death.  He added, once you finish a boat you forget it and move on.  So he remains nameless to me, and in deference to his wishes I will publish this photo of him looking away from the camera.