'kikugi' japanese trunnels

[Aramas]

I was reading this Sano interview (http://www.boatsyachtsmarinas.com/interview/html/sano.html) and it describes the traditional japanese trunnels (kikugi) as "Mahogany nails (long, slender square pyramid shape) are used which have to be burned, to make the edge hard."

http://www.boatsyachtsmarinas.com/interview/assets/images/sano2.jpg http://www.boatsyachtsmarinas.com/interview/assets/images/sano3.jpg

Does anyone have any more info on this method? It appears to be used on quite light construction, unlike European trunnels. Must be a pain to cut thousands of tapered, square trunnels and 'harden' them with fire though.

[ 11-09-2005, 10:56 PM: Message edited by: Aramas ]

[Dave Fleming]

I am not familiar or to be more frank aware of this type of construction.

Yet, another craft seems to be slipping away from us.

Kyoto wood workers, Saki blacksmiths, etc...

Have you more info on this boat building technique?

[Bob Cleek]

Interesting! I'd expect the hardened edges of the treenail would bite pretty well. Something to play with in the shop during the slow times! Worth experimenting with. Sure would beat heading rivets! Who is this guy? I'll have to check my back issues. (I vaguely remember the article.) WB should be doing more articles on these sort of techniques and less "boat porn."

[Bruce Hooke]

For whatever it is worth, I read somewhere, maybe in Understanding Wood, that tests have show that 'fire hardening' does not in fact harden the wood. I'm sure there could be debates about what exactly the right procedure is for 'fire hardening' and whether the test were conducted using said proper procedure, but at the least it would be unwise to assume that 'fire-hardening' will definitely do anything (other than change the color of the wood!).

[TimothyB]

Bruce, I'm going to posit that the fire "hardening" procedure is not used so much to actually "harden" as to "cauterize" the surface fibers and thus allow the wood to penetrate easier. No fluff to get caught in the fluff you are trying to drive through.

Like how a bright steel nail draws easier than a ring nail. Same hardness.

[Spissgatter W-9]

If I understand you correctly, it may not be that big of a pain if you have a band saw. I was using for a different purpose ie. to plug old holes in frames after removing corroded fasterners. Refastening Trine required hundreds of little pyramids. Each was dipped in thickened epoxy and tapped in. The next day I would saw off protruding portion then rebore with a Fuller tapered bit and countersink. This gave good bite for the new silicon bronze screws.

These were cut out of red cedar stock about 4" x 4" square. I would begin by drawing a line about 3/16" longer than the length of the trunnel dimension all round (four sides). Next I would lay out the triangles alternating points first one way then the next. Looks like a zig zag when done. Then I would rotate the board a quarter turn and layoff the triangles again being sure to keep wide ends together. Cut on lines pushing end of board into blade. Rotate 1/4 turn and repeat. Final cut is accross on original line to free all the little pyramids. There are waste pieces to discard. If the pyramids are 3/8" at base, should be able to get about thirty or so each time. With some fiddling you should be able to get trunnels with the taper/length you are looking for.

Is this clear as mud? I could perhaps draw a picture if this is helpful. Someone may have a better method.

[Bob Cleek]

Yea, we'd have to ask Doc Jaegels whether fire hardening really hardens wood. I do remember it being a technique that has been used. They used to do it with tool handles and baseball bats, as I recall. The use of treenails is really something that has been overlooked since the invention of the spike and later, the screw. I suppose there is some "time is money" advantage to metal fasteners. I have heard, though, that nothing beats a correct treenail for its purpose. Making them, drying them, driving them with blind wedges and so on would surely be tedious. The advantages, though, are great. Primarily cost and the fact that you will never have any nail sickness, refastening problems, and so on. No bungs to set. No problems fairing the hull. If you do refasten ever, it's a snap. No old fastening to remove, since it's all wood. I have often thought that an unwedged treenail would be fine if epoxied in place. The real stress on plank fastenings is sheer, not pull, anyway. A good treenail is as good as a metal fastening in sheer.

This bears more discussion here. Maybe some of the old timers who have worked on treenail fastened hulls might give us some insight as to how they hold up. No question they are easy to turn out if you don't have to notch and blind wedge them and they sure are a lot cheaper than everdur bronze! I've come across them in larger carvel planked hulls, but never in light clinker building. Could be a real "discovery" if we could do it like this Japanese guy does. This must have been how they build European lapstrake hulls before metal fastenings were commonly available.

[yorgie]

Bill Gilkerson's kosterboat 'Elly' is trenail fastened and she has most of her original wood.The same old woodenboat aricle showed a new kosterboat being built with trenagles(norwegian spelling).

I'm sure much of the fastening was originaly done by apprentices and the manufacture of treenails was a cottage industry done by retired boatwrights.N

[Aramas]

I suspect that 'fire hardening' is actually just fast track seasoning of the wood surface, somewhat like case hardening of metals.

Here in Australia, a common building wood is OBH (Ordinary Builders Hardwood), which is just non-specific eucalypt that is served rather green. In its green condition it's not especially difficult to work (for eucalypt), and nails can usually be driven without pre drilling. However, after a decade or two it's virtually unworkable. I once burned out a big Skil power drill trying to bore big holes in it after it ate a 7" circular saw. Driving in nails was impossible without drilling first, and even then they had to be only one size smaller than the nail. It was a monster. Perhaps 'fire hardening' is a bit like that, but only on the surface. I know that a lot of stone age cultures used the technique for weapons, tools and wooden bowls etc., so there must be something in it.

I found an interesting document on Norwegian wooden boatbuilding (http://www.shipspreservation.com/admin/docs/28.1.PDF) which has a fair bit to say about trunnels, including octagonal and headed varieties, but they only seem to come in Supersize - ie "One rule, regarding the dimensions of trunnels, which appears to work well, is; half the thickness of the hull planking plus 2-3 mm. At the same time, they should not be thinner than 25mm."

Ick. An alternative to a brick construction for outhouses, it would seem.

Trunnels have a long history in asia also, although a lot of traditional boatbuilders have since replaced them with steel nails or drifts. Generally, se asian countries that didn't use lashings used trunnels not only in the usual way, but in some cases also to edge fasten planks together. It's difficult to find detailed information though. If Lucky Luke is reading this then he might be able to shed some light on the subject, living in the region as he does.

That Sano boat looks so light and elegant. It's like wood epoxy construction without the goo. I'd love to learn more about the method.

What interests me so much about trunnel construction is that, while epoxy construction has done a lot to make boats quicker and easier to build for those of us whose boatwright skills are somewhat less than elite, the cost of epoxy, glass and assorted paints, powders and goos, even for a twently footer, can easily equal ten times the annual income of the majority of human beings on this planet. Wood epoxy construction is a privilege of suburban consumerist hamster wheel riders.

I would like to see simple, pretty boats designed to be attainable for everyone, not just the citizens of countries that are willing to go to extreme lengths in order to keep poor, brown people barefoot and starving. Even in developed countries, there's a lot to be said for eschewing industrial materials such as metals and petrochemicals.

[ 11-11-2005, 12:58 AM: Message edited by: Aramas ]

[Bruce Hooke]

Aramas, that makes sense to me. Heating a piece of green wood might well have a lot more impact than heating a piece of air-dried wood. So, the old guys with their spears would have had a good reason to do it and the modern makers of hammer handles might have just picked up on the old tradition as a marketing technique, even thought it did not do anything for the already dry wood in the hammer handles.

[Bruce Hooke]

Originally posted by Aramas:
"One rule, regarding the dimensions of trunnels, which appears to work well, is; half the thickness of the hull planking plus 2-3 mm. At the same time, they should not be thinner than 25mm."This does get at one thing I have pondered with regard to trunnels on small boats. The picture at the start of this thread notwithstanding, I wonder if at a certain point the frame size just gets too small to permit a trunnel of sufficent size to be driven through it without excesively weakening the frame. A small boat could easily have frames that are only 7/8" square. Even a 1/4" trunnel would remove a lot of wood from the frame, and, it seems like a 1/4" trunnel would be a lot less strong than, say, a #8 screw. As the boat at the start of this thread demonstrates, it is clearly possibly, but I would want to look quite carefully at how it was being done and think about the implications before applying the same technique to a boat that was designed to be held together with screws.

[Aramas]

I agree. Our tradition of building with trunnels is not suitable for lightweght construction, and we invariably suffer from the Not Invented Here syndrome when it comes to exploring alternatives. however, with bronze, stainless or monel fasteners commonly exceeding a dollar each, there's certainly an incentive for looking at other traditions.

Hopefully I can get some first hand experience next year in asia. Anyone know a nice boatbuilding town with beach bungalows for a couple of dollars a night? Oh, and good cheap beer, but that goes without saying smile.gif

[merlinron]

doesn't the process of "fire hardening" crystalize the resins just beneath the chared layer of wood? wouldn't that actually case harden the surface?. that's how i understand it works, anyways.

[Trog]

http://www.boatsyachtsmarinas.com/interview/assets/images/sano2.jpg

That looks surprisingly like my chin :eek:

[Bruce Hooke]

Originally posted by merlinron:
doesn't the process of "fire hardening" crystalize the resins just beneath the chared layer of wood? wouldn't that actually case harden the surface?. that's how i understand it works, anyways.Possibly, but then why have tests on "fire hardened wood" shown that it was not in fact any harder than regular wood? I suppose it is possible that it only works on woods that are high in resin, but those woods are going to be hard to fire harden because they are going to want to catch fire and burn up.

[landlocked sailor]

This is interesting too. http://www.millerdowel.com/about-us/history.html
Rick

[Dave Fleming]

I too have looked at those Miller dowels with an eye towards boat building application.
Initally boat building quality dowels were not offered now I see that they are.

Sadly the cost is prohibitive!

A trunnel must serve two functions.
One is in shear the other is in withdrawal.

On the few and very distant past times I worked on replacing trunnel fastening, it was with much larger scantlings.
4 inch plank and 1.5 inch trunnels wedged at both ends.
Ayup, you can either blind wedge or flush wedge in inboard side and flush wedge the outboard side. No getting around it you have to wedge to get the desired result.

How ya goin' to wedge 1/2 inch trunnels effectively?????????????

[ 11-12-2005, 05:04 PM: Message edited by: Dave Fleming ]

[Aramas]

Being complicated, expensive and requiring glue, it would seem to me that those Miller dowels manage to remove most of the advantages of trunnels. You may as well just screw it or glue it.

You might be able to get away without wedging if the trunnel is driven in oversize - maybe oven drying (or 'fire hardening') them to shrink them a bit, making them square or ovoid, or a bit of taper...hey, that sounds like the Japanese jobbies smile.gif

Seriously, using oversize, overdried dowels (think wooden drift bolts - no one wedges them) should be pretty strong, and you wouldn't have to worry about the wedges falling out. Oversize or square dowels would crush a lot of wood which would expand when wet, holding them tight.

There's an article on building Indonesian Pinisi (http://www.kastenmarine.com/phinisi_history.htm) that doesn't mention wedging the trunnels.

[ 11-12-2005, 12:23 AM: Message edited by: Aramas ]

[Dave Fleming]

Guidance on Inspection,
Repair, and Maintenance
of Wooden Hulls
ENCLOSURE (1) TO NVIC 7-95
COMPILED BY THE JOINT INDUSTRY/COAST GUARD
WOODEN BOAT INSPECTION WORKING GROUP
August 1995

From page 15.
Treenail ( Trunnel)
A wood dowel used as a fastening:often fitted with a wedge in the dowel end to hold it in place.
Dense wood such as Locust is used for dowel.

See:

Trunnel Discussion (http://www.woodenboat-ubb.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic&f=1&t=005147&p=)

See:
Duyfken Replica (http://www.duyfken.com/replica/replica-08.html)

Those Indonesian vessels were planked "blind trunnel fastened", which in my mind means that the trunnel was buried between the planks.

On the west coast of the United States in San Francisco in particular where I worked on refastening a Sacramento River tug and a Miki-Miki tug we used trunnels that had been in the yard, Anderson and Christofani, for a very long time. They were a mix of Madrone, Pepperwood and Doug Fir with wedges of Australian Red Gum or Iron Bark. The heads were still square from the lathe. For plank fastening they were driven into blind holes meaning that the end was buried into the frame whereas the ones used to fasten the futtucks were through driven and wedged on both ends. The plank ones were driven till the square was set a bit into the plank and then sawed flush, the end split with the grain with a chisel, wedge driven and sawn flush, coated with Red Lead paint.

[ 11-12-2005, 02:01 PM: Message edited by: Dave Fleming ]

[emichaels]

I wonder if the practice is similar to fitting ash round spindles on arrow backed chairs. The traditional methode is to hold the spindle end over a fire or hot heat source to drive off water and slightly shrink the end. Insert into the hole bored for this spindle and let it expand back out to stable MC. It is impossibe to pull one out by hand.
Eric

[Dave Fleming]

Hmm, I seem to be hijacking 'A's' thread on this particular Japanese boatbuilding technique.

Apologies.

Perhaps this should be continued in a separate thread.

[ 11-12-2005, 03:15 PM: Message edited by: Dave Fleming ]

[Bob Smalser]

Originally posted by Dave Fleming:

How ya goin' to wedge 1/2 inch trunnels effectively?????????????http://pic3.picturetrail.com/VOL12/1104763/2594266/26720357.jpg

These blind trunnels and a dozen or so others I've done have held up well to 30 years with no glue 'cept for the wedge.

I don't see why they wouldn't work on planking this thin. The problem is easy disassembly for repair if the trunnel is glued in...otherwise, you just drill out the wedge and tap the plank free.

[PeterSibley]

posted by Dave
How ya goin' to wedge 1/2 inch trunnels effectively?????????????
Very,very carefully mate! But it probably is possible and if you were going to go this route it would have to have been the idea the whole time,no last minute changes .The frame sidings are going to have to be increased to compensate for the material removed by boring.In my case I'll stick to copper nails and roves...cheap too. smile.gif

[Rick Tyler]

Originally posted by Aramas:
(...)not just the citizens of countries that are willing to go to extreme lengths in order to keep poor, brown people barefoot and starving. Can we please keep this sort of editorializing in the bilge where it belongs? Thanks.

[Lucky Luke]

Originally posted by Aramas:
Trunnels have a long history in asia also, although a lot of traditional boatbuilders have since replaced them with steel nails or drifts. Generally, se asian countries that didn't use lashings used trunnels not only in the usual way, but in some cases also to edge fasten planks together. It's difficult to find detailed information though. If Lucky Luke is reading this then he might be able to shed some light on the subject, living in the region as he does.
Sorry, I missed this thread!

I cannot comment on this Japanese method, not knowing it, but can answer your question regarding edge fastening with trunnels: it is simply that:
http://www.imagestation.com/picture/sraid194/p2f0647b2aca140d75841283cf7f9c405/f1677e6a.jpg
:blind wedged rectangular trunnels. However, these are replaced by nails now...won't last as long!
The other method is:
http://www.imagestation.com/picture/sraid194/pfbfb8678f0cc5aa55f1759e19935d78d/f1677f32.jpg

In the "other thread" about trunnels (this respect of one's thread makes replies a little complicated my dear Dave ;) ), you were discussing the respective "solidity" of Western and Asian boatbuilding.

I won't argue that Northsea is winter is not harder than South China Sea during monsoon, but still, the big chinese junks were able to endure typhoons and cross oceans...Ships like this one are no babies...
http://www.imagestation.com/picture/sraid183/pa4336b81acc65745363b67836b8aa3bf/f2b70cdc.jpg

That is going away from the thread, yup!Sorry and... never mind! :cool:

Then, one essential difference between European and Asian construction (referring to "the other thread") is that the European one is rigid while the Asean is flexible .

http://www.imagestation.com/picture/sraid194/p76ca49255a8c5cb0c8c2dd2087031a93/f167a869.jpg

I don't think its much lighter though, unless we are talking of the remarquable bamboo bottommed or stiched boats of central Vietnam!

[ 11-19-2005, 01:37 AM: Message edited by: Lucky Luke ]

[Aramas]

How about these long, lean racing canoes in Cambodia?

http://www.khmer440.com/wp-content/battyboats1.jpg

[jzeigler]

http://www.swanboat.org/

I've paddled similar boats in competition with the US team in Thailand. There are a couple of types of these traditional war canoes. The International Swan Boat, for Thailand racing is 15m by 1m. These boats have 20 paddlers and race 650m sprints. These are traditional carvel planked and around since 1988 and built to stimulate international competition in Thailand. They won't release plans. I've tried so I can make a model.
There is also the "longtail" which can be as long as 100ft and made from a single teak log. 44 paddlers for this one and they don't allow foreigners in them.
China has the dragonboat which I'm sure you're all familiar with. I've done that with the US team too. These are also war canoes and are about 15m by 1m. Again, 20 paddlers, and the course is either 200m, 250m, 500m or 1000m of some of the most anaerobic exercise of your life.
http://www.phillydragonboat.com/
Incidently, I am told this is the 2nd most popular sport in the world behind soccer. Tens of thousands of clubs in china alone.

[Lucky Luke]

jziegler, I think that aramas means the long shaft engine propelled boats by "longtail".
Is that right?
Anyway, folks, I had a motorcycle accident Saturday, and a broken arm :rolleyes: . So I shall not be very present here for a few weeks, since it makes typing (and everything else) much longer :( !
See yah!

[Andrew S/Y Rocquette]

Originally posted by Aramas:
Anyone know a nice boatbuilding town with beach bungalows for a couple of dollars a night? Oh, and good cheap beer, but that goes without saying smile.gif Yep - Nungwi on the northern tip of Zanzibar...still build dhows by hand.

;)

edited for s-p-e-l-l-i-n-g...

[ 11-21-2005, 04:14 PM: Message edited by: Andrew S/Y Rocquette ]