"NOT SO DIVINE WIND?"

(Click on Photos to Enlarge)

There have been reports for many years of fishermen collecting artifacts related to the Mongol invasion around the island of Takashima.Ceramic fragments, bricks, and even anchor stones can be found just by walking along the island’s shore.A statue of Buddha was raised from the sea about 200 years ago and is now placed in a local shrine.

Although the legend of Kamikaze survives, some scholars suggested that the number of ships reported in the historical documents was highly exaggerated as it is difficult to believe th"at the Mongol Empire had the resources to gather such a massive fleet of more than 4000 ships.

To make an interesting note, many timber fragments discovered at the site show multiple nail holes in various directions, which seems to have served no particular function; sometimes two or three nails are driven within 1 cm intervals.One suggestion is that shipwrights gathered reused materials from older vessels to construct new vessels, or that some ships were extensively repaired.

Hayashida, and others mentioned that some of the storage jars found at the site were not well-fired, indicating that the jars were manufactured in a hasty manner.Also, iron Nails used for building ships contained high percentage of sulfer and other impurities, suggesting they were using weak nails.

My hypothesis is that some of the ships were much older vessels, others newly constructed, but all were not built to last. This ill-preparation may have been the real cause for the failure of invasion. I would first like to briefly consider historical documents, and then discuss archaeological evidence in more detail.

HISTORICAL EVIDENCE

Yuan Shi is a collection of chronicles of the Yuan dynasty. One section of the chronicle notes “To conquer Japan, (Kublai) ordered the construction of 600 warships in four provinces (in Southern China).” However, it is said that most of the provinces were not able to make their ships in time. Another section of Yuan Shi mentions an official’s concern over these orders and how they may have resulted in a local revolt.

An inscribed wooden tag found at Takashima provides some interesting evidence. It reads “In the first year of (This part is missing)., (a name of certain official) has repaired and inspected this.” This seems to be an official sign that “something” was inspected and approved after a repair. It is difficult to determine what the official inspected; however, the word “repair” implies that it was a large equipment and not a small object. If this note was for a vessel, it indicates that old vessels were gathered, repaired, and inspected for use in the invasion.

ARCHAEOLOGICAL EVIDENCE

For the archaeological evidence, I will describe the nature of the site itself, a mast step, and bulkheads. Unfortunately, no large sections or complete hulls of ships have been discovered. The site likely contains different types of ships from China, Korea, and Japan, and it is extremely difficult to identify which timber fragments came from which ships. It is analogous to reconstructing 4000 different jigsaw puzzles with only 1% of the pieces remaining and no templates.


For a comparative analysis, I will use the Quanzhou and Shinan ships, the best example of vessels from this period. These vessels had a V-shaped hull with a keel and several bulkheads; which are typical of southern Chinese merchant ship construction. Bulkheads, which are vertical/transverse partitions within a hull, were used as a main support for the hull planking instead of frames. Other than these important shipwrecks, information regarding Medieval East Asian shipbuilding technology is minimal and new discoveries may change how we look at the shipbuilding technology of the era.


THE SITE
More than 80% of the timber fragments discovered at Takashima are less than 50 cm long. Nearly all the timbers discovered at this site are single, isolated fragments. There are two possible explanations for the scattering of ship timbers.

The first is post-depositional disturbance, caused by breakup of whole sunken ships over the last 730 years due to natural forces, such as waves and currents. The second possibility is that the ships were smashed into pieces prior to or during their sinking and, therefore, there never were complete hull remains. Hayashida has researched the deposition rate in the past, and there seems to be a stable rate of silt accumulation at the site.The site is buried below 1- 1.5 m of loose silt. The layer containing artifacts from the invasion is compacted silt, and the layer below is a mix of compacted sand and shells.

The four anchors were found in line, all oriented in the same direction, and their attched cables indicated the direction of the vessels;
the anchors do not seem to have been disturbed after they were set at the time of the storm. The stratigraphy, therefore, seems to be fairly stable, indicating a major breakup of vessels prior to deposition. This implies that the vessels may not have been well-constructed. No doubt that the site has been disturbed, however, I believe that the timbers would not have been widely scatterd if the joinery were stringer.


MAST STEP
One of the most important artifacts to indicate that the ships were not well-built is a mast step. It is 1.3 m long and has two rectangular holes. Two timbers were inserted into these rectangular openings, placed side by side of the mast for support. Medieval Chinese vessel lacks standing rigging and thus they require extensive support structures for the mast.


Typically, the mast step is an important structure that not only supports the mast but disperses its weight to the hull. As seen in the Quanzhou and Shinan ships, mast steps were fitted and carved to fit to the bottom of the V-shaped hull. Compared to this, for a mast-step from Takshima, the rectangular holes appear off-center, and there is another hole to the side. Also, the mast step appears to have either been constructed in a hasty manner, or the shipwright did not see any importance in making the mast step. Perhaps, with so many ships being built, inexperienced workers were hired to create the fleet.

BULKHEADS
Bulkhead planks were an important discovery because they are some of the only timbers that were found connected to one another.The maximum length is 5.7 m across, and the planks are approximately 13 cm thick. The plank seams are joggled at several locations. This indicates possible repairs, or, perhaps, the shipwright decided to make the bulkhead with several timber pieces due to a lack of large, high-quality timber for a vessel of this size.


The two bulkhead planks were fastened together with iron nails driven diagonally from both sides. The same construction can be seen on both the Quanzhou and Shinan ships, and it is believed to be a typical construction feature of bulkhead.

One aspect that I would like to emphasize is the method of attaching planks to the bulkhead. The joinery of bulkhead to hull planking of the Quanzhou ship uses gua-ju nails, which are L-shaped brackets. These iron brackets are inserted from the outside of the hull from a small cut, and fastened to the surface of bulkhead.

The Shinan ship uses stiffeners to join planks to bulkheads. A stiffener, described by Jeremy Green, is a long wooden peg that is set from the hull planking. Stiffeners are then attached to the surface of the bulkhead by nails. This construction is similar to that of the L-shape bracket of the Quanzhou ship, but made of a long length of wood. These two types of fasteners held the bulkhead together and secured the planks. However, the bulkhead from Takashima lacks these features. I found no evidence of the use of brackets, stiffeners, or any trace of similar joinery.

Instead, holes found on the sides of the bulkhead hint that nails or bolts were used to attach the bulkhead to the planks. These holes are not deep: approximately 10 cm, and the interval between these holes is closely spaced at 10-13 cm. It is difficult to say if gua-ju nails or stiffeners are stronger than nails or bolts, but it is time-consuming to construct a ship with these fasteners.

When compared this section of a hull to that of Shinan and Quanzhou ships, the use of iron brackets or long stiffeners appears to disperse the stress on the bulkhead and to the hull, while the use of nails or bolts will put the stress only around joinery. Thus, there is reason to believe that gua-ju nails or stiffeners are a better choice if shipwrights had the time to install them.

CONCLUSION


While recording timbers from these important shipwrecks, I focused my research on finding evidence that the vessels used for the invasion were hastily constructed. Historical documents imply this was the case, but the archaeological evidence cannot yet fully support the hypothesis. Despite much evidence suggesting that the ships may have been built with weaker construction, no conclusive evidence was found. Still, this is one of the most important shipwrecks sites in East Asia. There is a greater chance of finding a more or less complete hull once a full-scale survey is conducted.
It is also possible that the shipbuilding technology of East Asia can be studied here; Takashima is truly an international site and requires assistance from Korea, China, and rest of the world to fully realize its true significance.

The investigation has only begun, we still have thousands of ships to find and research.

3D Reconstruction of the Site

The buddha that was raised

Possible Repaire?

More Repaire?

The nail that was analyzed

Chinese Landing Craft

Tag found at Takashima

Photo of Sea-floor

Quanzhou Ship

Site Plan from 2002
The Anchors
The Mast Step
The Mast Step on sea floor
Mast Step of Shinan Ship
Making Photo Mosaic
The Bulkheads
The Bulkhead Joinery
Gua-Ju Nails of Quanzhou
Shinan Ship
Bulkhead to Plank Joinery
Takashima Ship
Photo of Sea floor

SUGGESTED READINGS
Delgado, J
2003 “Relics of the Kamikaze” Archaeology 56 (1)

Green, J., and Kim, Z.
1989 “The Shinan and Wando Sites, Korea: Further Information” The International Journal of Nautical Archaeology 18 (1):33-41

Green, J., et al
1998 “The Ship from Quanzhou, Fujian Province, People’s Republic of China” The International Journal of Nautical Archaeology 27(4):277-301

Inoue, T
1991 A Nautical Archaeological Study of Kublai Khan’s Fleets M.A. Thesis at Texas A&M University

I would like to thank Mr. Kenzo Hayashida and the members of the Kyusyu Okinawa Society for Underwater Archaeology, as well as the local government of the island of Takashima which allowed me to analyze the timbers from these important shipwrecks.Kazuma Kashiwagi, a student from Ibaraki University, and George Schwarz, from the Nautical Archaeology Program at Texas A&M University, participated in recording the timbers, and I greatly appreciate their work in Japan. The Institute of Nautical Archaeology and RPM Nautical Foundation have provided funding to conduct this research, and I appreciate their generosity. Without their support, this project would not have been possible.

BACK TO MAIN PAGE

Photo Credits:

Moko Shurai Ekotoba Scroll: Chinese Landing Craft

Green. J. 1998: Quanzhou Ship, Gua-Ju Nails of Quanzhou

Green. J. 1989: Mast Step of Shinan Ship

Takshima Board of Education: Tag found at Takashima, Site Plan from 2002, The Anchors, The Mast Step on sea floor, and Photo of Sea floor