Turning the Hull

Merry Christmas!  We are actually further along than this; I've been remiss about postings for the last few days, but plan on catching everyone up.

Rolling the boat over turned out to be far easier than I thought.  The last thing we did the night before was cover the boat in a thick coating of tempura oil (soybean).  We gave the bottom another coat first thing in the morning.  Then we made sure that the bars holding the sheer apart were good and tight.  We clamped some scrap at the sheer in the way of the strapping so it wouldn't mar the hull.  After rigging straps under the hull fore and aft, connected at one end to chainfalls, we lifted the boat just enough to get the sawhorses out and then, while suspended there, Shimojo san's son and his younger brother just grabbed the rail and spun her over.  I had my video camera all set up and ready to go, so I got all ten seconds of it.  I realize that the oil was a real help in this process, as the boat just slid over the straps.

Mrs. Shimojo had her customary place at one of the chainfalls, her husband at the other.   It turns out that she worked side-by-side with her husband in the boat shop for most of his career, and daily after his accident.

After sanding the bottom seam inside the boat flush we laid out the location for our huundu.  Tomorrow we have forty of them to mortise and install.

Finishing the Hull

Things have happened quickly the last few days on the boat.  In the interests of time I will just post photos from the last three days and throw captions under them.  My apologies for the brevity but remember, you should always be able to click on a photo and enlarge it.  Take a look around.

We fit the gwa gwa at either end using the suri noko method, after planing to the best fit possible, running a saw through the seam several times to make the fit perfect.

This is new for readers of this blog: The endgrain joint of the gwa gwa, which is a very shallow V-shape, is pounded with a hammer, compressing the fibers so that after the pieces are put together these fibers will expand and make the joint absolutely watertight.  This method is used in other ways throughout Japan.  I have been wondering how we were going to handle this large endgrain joint.  Shimojo san pounded this to a point where the cedar had been compressed at least 1/8".  He worked a little more gently near the edges so not to split them.  Then he very lightly planed the high spots and we put the piece in place and did several more passes with the saw in the joint.

Helping and researching at the same time: I brace the gwa gwa while Shimojo san pounds the endgrain while I take notes on this method.

Shimojo san said that in the old days, the sabani's planking came together along the bottom near the bow.  He said that the gwa gwa was much smaller and the seam ran level (as indicated by the batten).  Shimojo san said that this plank seam underneath the bow was very weak (but partly the result of very wide planking material).  The current form evolved and Shimojo san believes it greatly improves the boat.

Planing the forward gwa gwa to a rough shape.

The gwa gwa dogged down with staples.  We've glued it to the planking (even glued the endgrain).  Then we installed huundu and bamboo nails.

A detail of the huundu and nails holding the gwa gwa aft.

As of yesterday, awaiting final sanding.

Spent over half the day sanding the hull, 60 grit followed by 100 grit.

In the old days it was shark liver oil, which I am told you could smell at a great distance (and it didn't smell good).  Now we are using soybean oil, the kind used for cooking tempura.  We put a generous amount on the boat at the end of the day today.  Shimojo san said it could soak up plenty.  I am not sure if we will put more on tomorrow or not, because we are turning the hull over tomorrow.  Seems that an oily boat would not be a good candidate for rolling over, but I will find out.

Mr. Rudder

A couple of weeks ago an older man stopped by the shop.  He introduced himself as Kaji san, a pseudonym that means Mr. Rudder, and told me he was living aboard his home-built catamaran in the harbor.  I have seen him a few times in the morning when I am down by the ferry port before work, and he has always invited me over to look at his boat.  His invitations are so earnest, but since we work seven days a week its hard to do anything extracurricular.

This morning I saw him again and realized I had enough time for a quick look at his boat.  We walked over and he explained that his boat has been out of the water for some time while he is working on it.  Sure enough there it was in the lot, a big catamaran designed by James Wharram (http://wharram.com/index.php).  He told me he built her out of 9 mm marine plywood.  This is just 3/8" which sounds pretty light to me for a boat this size.

He named his boat LARK and he appreciated the meaning of the word.  He also has it spelled there in katakana, one of the Japanese phonetic alphabets.  Since there is no L sound in Japanese, a strict reading is "raku" which in Japanese means "ease, comfort, to have fun."  Its a bilingual synonym.  He has twin 15 hp outboards that sit in a pair of interesting engine wells.  You can see them in the background right next to the hulls.

Note his mailbox (with the red T).  The service provided by the Japanese post office is mind-boggling, so it didn't surprise me that he could establish his own delivery right to his boat.  He's been here a few years, slowly working on her.  Those are the engine wells viewed from the bows.  I assume they swing up.

His masts are straight aluminum pipe, no taper.

What really amazed me, and if he hadn't pointed it out I would have never noticed, is that he took off his rudder hardware and replaced the gudgeons and pintles with lashings!  He said that this was a suggestion from a friend in Kagoshima, a place he stayed in transit to here from Osaka, where he built the boat.  He and his friend were inspired by the sailors of Polynesia in making this change.  The rudders swung kind of stiffly on the lashings, but he assured me that he had complete confidence in this arrangement.  Of course if they showed signs of wear they'd be simple and inexpensive to replace.  Four lashings hold each rudder.  What an idea!

Gwa Gwa

This post could be entitled Guwa Guwa if you wanted to be strict about Japanese kana (there is no way to write "gwa gwa" in phonetic Japanese) but to do so would made it read differently than it sounds.  My main title is the way it sounds.

I left readers at the end of my last posting with a cliffhanger: what did Shimojo san say in response to my question about building sabani with just glued seams?  I was actually surprised when he responded that he thought modern glues were amazing, and that it might actually work.  After sixty years of building boats he is not willing to try, mind you, but I thought his answer was very progressive.

A few moments later he said to me, "Before glues, do you know what we did when we could see daylight through a seam?  We would put shark liver oil in the seam."  He said that this oil was thin, but that spread on a seam it would stop small leaks.  Fishermen also coated their boats inside and out with this oil three or four times a year if they wanted to preserve them.  The boats turned black and Shimojo san told his own joke, calling the old sabani the well-known name "kurobune" or "black ships" (this is the common name for the ships of Commodore Perry's fleet that forced Japan in the 1860's to open its borders).

Cross cultural note:  I read in an excellent true travel adventure story, Motoring with Mohammed, that in Yemen fishermen coated their boats with a mixture of shark liver oil and pureed dates.  Shimojo san doesn't think it is possible to get shark liver oil today.

The last steps in finishing the soko included putting in the bamboo nails to supplement the huundu fastenings, and rounding the chine.  And our order here is reversed from the old days: before glue Shimojo san would have put in the bamboo nails to hold things together so he could pound on the boat, chiseling for the huundu, and not have things move.

I mentioned that the boat looked like a sea urchin (a popular food in Japan) and that got a big laugh.  Note how at the hood ends of the bottom's side timbers we "stitched" them in with some nails running horizontally.

The pieces fore and aft that complete the bottom are called gwa gwa.  This is Iejima hogen ("gwa" means "a small thing") and in standard Japanese these could be called omotejiki and tomojiki, given their similarity to parts in standard Japanese boat construction.

The stern

As you can see, these were roughed out well over the size required.  But these photos also give you some idea of the original size of our soko, and just how much material we took off, largely with the electric plane.

The bow

Once again I asked, just to make sure, if we could just cut this excess off with a saw.  Shimojo san said no, and pointed out that the size of our rough timber gave him the freedom of fitting it so that all the sapwood (the white part, much less rot resistant) could be removed.  Perfect answer.  And we will remove all this with the electric plane, and I am beginning to realize that it doesn't take that much longer (it's just messy, dusty, noisy, etc.).

The gwa gwa join the soko with a shallow V-shaped butt joint.  The edges of the planks were first straightened, then the bevels made even throughout to make up for the twist in the planking.  Shimojo san and I worked on fitting the butt joint running a small cross-cut saw in the seam, closing it tight after each pass by tapping the end.  We quit for the day just as we finished the bow; Shimojo san said it was too dark to see anyway.  I asked him again why there were no lights in the workshop and he said that if there were, one would be inclined to work too much!

Point that out to your boss tomorrow.

Bottom's On

Once we finished fitting the last seam along the bottom we broke for lunch.  After lunch I was a little surprised as some of Shimojo san's family started to join us in the shop: his wife, daughter, son.  I was there as well as our volunteer, Shimabukuro san.  Turns out it was time to glue the bottom timber to the side planking.  

Gluing that seam had not been mentioned before so I was a little taken aback.  I asked Shimojo san about this and he said that once we start chiseling the mortises for the huundu the pounding of our mallets is going to move the bottom around, so we have to stiffen hull structure with glue.  I asked him what he did in the pre-glue days and he said that he would have put in the bamboo nails at this point (we've always installed those after the huundo up until now).  He said that the bamboo nails would have gone in at a slight angle, not parallel with the plank face, driven in from the side of the bottom timber into the side planking.  We also cut a few inches off the ends of the bottom, not a flat face but in a very slight V.

Bondo, the most common Japanese wood glue, is a white, urea resin-type glue.  Shimojo san adds an accelerator that amazingly kicks the stuff off in about twenty minutes.  Since we always quit for the day after a glue-up I am not sure why he bothered, but in the accelerator went (a white powder) and that's why the family had joined us: because we needed lots of hands to scramble around, spreading glue fast, hoisting the bottom into position with the chainfall, pounding in dogs (staples) to clamp it together, etc.  It reminded me of the frenzy that always accompanies steam bending in the West.

Shimojo san mixed a small batch of glue and stirred in fine sawdust (we've got plenty of that) for a filler.  The bottom of the boat has lots of holes, from the staples in particular.  As the rest of us worked he went around filling dents, dings and holes.

Shimojo san had already laid out the location of the huundu, spaced as always every shaku (foot) down the sides seams, to within about two inches of the ends.  Thirty-eight in all.  With the bottom dropped on we pounded in staples at points midway between our huundu layout, both inside and outside the boat.

Excess glue wiped up, tools, hands and clothing cleaned off, shop swept, end of day.  Time to sit around for awhile and talk.

The next day I sat down to start installing huundu.  I chiseled out flat spots along the seam (our bottom is still a good 1/4" oversize on the inside and outside) where the huundu go.  Shimojo san told me he would put in the four at the ends.  He said that those close to the endgrain were tricky.  After lunch Shimojo san's son took over for him and basically with two people working it took most of the day to mortise and install all the fastenings.  After we roll the boat over we have matching huundu for the inside seam.

An Aside:

Some readers might be wondering with all this use of glue why we are still relying on the traditional fasteners at all?  It's a reasonable question, and when I asked Shimojo san it's clear that while he appreciates the convenience of glue he doesn't trust it completely.  I have encountered this with some of my other teachers.  We glued some of our seams in Tokyo and Fujiwara san said that adhesives, in his mind, were good just to hold seams together so that dirt had a harder time working its way in.  To suggest to either of these men that they rely only on adhesives would probably, in their minds, call my sanity into question.  That said, these are large boats and in the water racking forces could be great enough to break these glue joints.  Wood movement alone could do the same.  Besides, that line of dovetail keys looks so interesting.

Postscript:

I did ask Shimojo san about using glue alone and his answer led to a shark story.  Too tired to write it all now, so look for my next post.