Turtle ship

Turtle ship (Geobukseon)
A turtle ship replica at the military museum in Seoul.
Type	battleship
Place of origin	Korea
Service history
Used by	Korean Navy
Wars	Japanese invasions of Korea (1592-1598)
Production history
Designer	Admiral Yi
Designed	1591
Produced	March 27, 1592
Number built	3 to 5
Specifications
Length	100 to 120 feet
Width	30 to 40 feet
Crew	80 oarsmen, 50 soldiers

Turtle ship
Hangul 거북선 Hanja 거북船 Revised Romanization Geobukseon McCune-Reischauer Kŏbuksŏn

The turtle ship (also known as Geobukseon or Kobukson by its Korean name) was a large warship belonging to the Panokseon class in Korea that was used under the Joseon Dynasty between the 15th century and 18th century.

The turtle ship is famous for its helping the Koreans to win sea battles against Japanese ships during the Japan's Korean War (1592-1598). Contrary to public belief, however, the mainstay of the Korean navy in the war remained the panokseon warship.

The first references to turtle ships come from 1413 and 1415 records in the Annals of the Joseon Dynasty. These turtle ships were mentioned as "spear-ships" or "ramming ships" and were mainly used to thwart Jurchen and Japanese pirates. These early turtle ships soon fell out of use, though, because of a long period of peace during which Korea flourished.

The Korean admiral Yi Sun-sin is credited with designing and building the craft known today. His turtle ships were equipped with at least five different types of cannons during the [[Japanese invasions of Korea (1592-1598)]Japan's Korean War (1592-1598)]. Yi Sun-sin's turtle ships are claimed to feature iron-cladding. However, this assertion is controversial. He had three to five turtle ships built, while in 1782, there were at least 40 commissioned of them.

Construction

According to Nanjung Ilgi, one of Admiral Yi's personal diaries, he decided to resurrect the turtle ship in 1591 after discussion with his subordinates, thinking of possible foreign invasions. With their help, Yi constructed the first modern turtle ship. The admiral's diary, along with a book entitled Hangrok by his nephew Yi Beon, described the details about the structures, construction progress, and use of turtle ships, as well as testing of weaponry used in the ships.

After a year of research and construction, Yi had his soldiers complete the first modern turtle ship. It was launched on March 27, 1592. Its mounted cannons, with gunnery ranges of from 300 to 500 meters, were tested on March 12, 1592, one day before the Siege of Busan and the Battle of Tadaejin.

Structure

Several different versions of the turtle ships served during the war, but in general they were about 100 to 120 feet long (30 to 37 meters long), and strongly resembled the panokseon's bottom structure. The turtle ship was technically a hull that was placed on top of a panokseon, with a large anchor held in the front of the ship.

On the bow of the vessel was mounted a dragon head which emitted foggy sulfur gas to effectively disarray the enemy fleet formulation, as well as to hide the ship itself as it approached and maneuvered among enemy ships. The dragon head was large enough for a cannon to fit inside it too. The dragon head served as a form of psychological warfare in shocking Japanese soldiers.

In the front of the ship was a large anchor and below the anchor was a painted "face" that served as a ramming tool.

Like the standard panokseon, the turtle ship had two masts and two sails. Like them it also used oars to help speed it up, and this meant that, unlike the Japanese ships it fought, the turtle ship did not rely solely on the wind to move. Another main advantage the turtle ship had over its Japanese opponents was that the turtle ship could turn within its own radius.

The turtle ship had 10 oars and 11 cannon portholes on each side. Usually, there was one cannon porthole in the dragon head's mouth. There were 2 more cannon portholes on the front and back of the turtle ship. The heavy cannons enabled the turtle ships to unleash a mass volley of cannonballs. Its crew complement usually comprised about 50 to 60 fighting marines and 70 oarsmen, as well as the commander.

Hexagonal plates with sharp iron spikes protruding from them covered the upper half of the turtle ship. One of the main advantages of the closed deck was that it protected the Korean oarsmen and sailors from arquebus fire and arrows. The spikes were meant to discourage Japanese sailors from boarding the ships, because the primary Japanese method of naval combat at that time involved grappling an enemy ship with hooks and boarding it to engage in hand to hand combat.

Korean written descriptions all point to a maneuverable ship, capable of sudden bursts of speed. Like the standard panokseon, the turtle ship featured a U-shaped bottom hull which gave it the advantage of a more stable cannon-firing platform and the ability to turn within its own radius. The main disadvantage of a U-shaped bottom versus a V-shaped bottom is a somewhat slower cruising speed.

Contrary to popular belief, there were only around three to six turtle ships commissioned into the Korean Navy during the period of Hideyoshi's invasions of Korea; the mainstay of the Korean Navy was the panokseon warship, which was roughly the equal size of the turtle ship. This was because of the heavy resources necessary to build turtle ships. In a painting found in a Japanese castle, the turtle ships are depicted as three-storied mammoths, large enough in size to be compared to a modern ship. Cannons were positioned on the third floor, archers on the second floor, and troops on the first floor. There were also numerous handles that are thought to have been used to release water and suppress any fires onboard. Many weapons and functions found in the painting are thought by historians to have been years before their time.

Iron-cladding

Pros and cons

16th century Korean turtle ship in a depiction dating to 1795

It is sometimes asserted that the turtle ships, specifically their roof, had iron cladding. This is controversial, however. There is no clear evidence that the ships were ironclad. Generally, contemporary sources are silent on the construction of the turtle ship to the point that "even conceptual estimates of the design are seriously handicapped by limitations in the knowledge we have". Pertinent material comes mainly from two sources, Korean and Japanese war records:

Contemporary Korean records
Primary Korean sources are generally silent on the matter: Admiral Yi Sun-sin himself makes no mention of an iron-clad roof in his comprehensive war diary, although in a war report submitted on 14 June 1592, he refers once to "iron spikes" protruding from the roof:

"...under the threat of the coming Japanese invasion, I specially built a turtle-boat, with a dragon-head mounted at the bow, through the mouth of which one fires cannon, and with the back (roof-deck) studded with iron spikes (against enemy boarders). The crew inside can observe the enemy outside, but cannot be seen from outside. The ship can push into several hundreds of the enemy and cannonade them, ..."

• Yi Pun, nephew of the admiral and witness of the war, mentions briefly in his biographical record that the upper part (roofdeck) was covered with planks studded with bladed spikes, but gives no further details concerning the materials used.

Contemporary Japanese records

• One Japanese record of 'Ship-Battles in Korea' includes a description of a battle as experienced by two Japanese commanders on 9 July, 1592, three weeks after Yi Sun-sin's having described the features of his turtle boats. The relevant part reads:

"...About 8 o'clock in the morning the enemy fleet (Yi Sun-sin's fleet), composed of 58 large ships and about 50 small ships, began to make an attack on ours. Three of the large ones were blind ships (turtle-boats) covered with iron."

• Toyotomi Hideyoshi had a written request sent to Tokugawa Ieyasu for iron plating to help "counter" the Korean navy.^{[citation needed]} Some interpret this to be evidence of iron cladding on the turtle ships,^{[citation needed]} but it may simply be a reference to the need for better Japanese vessels to counter the Korean ships. ^{[citation needed]}

Later sources

• There are no known contemporary depictions, so that the first image of a turtle ship - and the one commonly referred to - is found in the Complete Writings of Admiral Yi which were edited for the first time two hundred years after the war in 1795. The brushwork departs in important aspects from the war records: While the hexagonal structure of the deck may give credence to the view that the turtle ships featured iron roof plates, the unexplained absence of the documented iron spikes have raised doubts, leading to complaints about the "lack of realism in the brushwork of literati" which "has introduced questions as to the authenticity of the records".

• Also, near the end of the 19th century, when Korea was under the threat of the French navy, an official was commissioned to build an ironclad ship "just like the turtle ship." The official's design of the ironclad ship was, however, too heavy and failed to float.

• A drawing from 1795 of Admiral Yi's turtle ship show a distinctive hexagonal pattern, strongly implying that something has been laid out over the wooden planking.

It should be noted that the iron-cladding of the turtle ship, if it existed, was motivated by very different fighting techniques than that of the 19th century ironclad. While the ironclad featured armour covering the sides, and later also all around, in order to protect the vessel from enemy shells, the iron roof of the turtle ship was meant to prevent the Japanese soldiers from boarding.

Weapons

Dragon's head

The dragon head was placed on the top of the ship at the bow. Several different versions of the dragon head were used on the turtle ships. The dragon head was first placed as an early form of psychological warfare to shock Japanese soldiers. One version carried a tube which could release a dense toxic smoke that was generated from a mixture of sulphur and saltpetre produced in the bowels of the ship. The smoke was designed to obscure vision and interfere with the Japanese ability to manoeuvre and coordinate properly. Another version of the dragon head had a cannon placed in its mouth so that the ship would appear to be more threatening.

Admiral Yi's own diary explains that a cannon could be fitted in the mouth of the dragon to be fired at enemy ships.

Iron spikes and armor

The iron spikes used on the turtle ship prevented the Japanese from boarding as it pierced their feet when attempting to board. Admiral Yi often covered the spikes with empty rice sacks to lure the Japanese.

Iron armor and the entire "shell" of the turtle ship itself was used to protect sailors and rowers from both cannon and arquebuses, unlike the panokseon battleships.

Cannon

The cannons were the main advantage of the turtle ships over the Japanese ships since cannons enabled the turtle ship to destroy an enemy ship at a distance. The turtle ship, like the standard Panokseon, could hold around 30 cannons. Usually, there were 11 gunports on each side and 2 gunports on the front and back. Several different versions of the turtle ship included about 24 to 36 cannons. A cannon could also be placed inside the turtle ship's mouth. Because of the gunports located all around the turtle ship, it could fire in any direction.

The turtle ship was equipped with Chon (Heaven), Ji (Earth), Hyun (Black), Hwang (Brown), and Seung (Victory) cannons. The Seung cannon was the lightest and ranged 200 meters, while the Chon was the heaviest and with a range of 600 meters. The Hyun and Hwang cannons were medium-sized cannons that usually shot fire arrows instead of cannonballs.

Tactical use

Yi resurrected the turtle ship as a close-assault vessel, intended to ram enemy ships and sink them, similar to their use in past centuries. It was rowed directly into enemy ship formations to disrupt their lines. After ramming, the turtle ship would unleash a broadside cannonball attack. Because of this tactic, the Japanese called the turtle ships the mekurabune (目蔵船), or "blind ships," because they would get close and seemingly blast and ram into enemy ships. This kind of attack was used during the Dangpo Battle, Battle of Okpo, and Battle of Sacheon (1592).

The turtle ship's main use of the plating was as an anti-boarding device, due to the top plating of the turtle ship and its protruded spikes. Grappling hooks could not gain direct hold on the plating, and jumping to the turtle ship often meant being impaled. The iron plating also made it more difficult for Japanese ships to destroy, because it allowed the turtle ship to survive damage from enemy cannons coming from above, as well as deflecting raining arquebuse bullets and arrows.

Later, the turtle ship was used for other purposes such as spearheading attacks or ambushing Japanese ships in tight areas such as in the Battle of Noryang.

Despite popular depiction, the turtle ship was not an extremely slow ship. The turtle ship had oar propulsion as well as sails, and was relatively lightweight due to its very limited plating. Admiral Yi constructed the turtle ship to be fast and agile for the purpose of ramming.

Turtle ships today

Turtle ships have been reconstructed recently for commercial and academic purposes. Keobukseon Research Center (거북선연구원), which is a private commercial company, has done much research on the original design of the turtle ship; and made several real-size reconstructions of them for commercial use. These were deployed in a Korean drama, The Immortal Yi Soon Shin (불멸의 이순신). Several museums host turtle ships on display, and people can visit and go inside a 1:1 scale turtle ship that is anchored at Yeosu. Models of the Turtle Ship are popular forms of decoration and gift.

Trivia

• As a result of the immense popularity of strategy video games in Korea, Koreans and the turtle ship are often represented in historical strategy games, f.e. Age of Empires II: The Conquerors.

Notes

^  The first account is in the "Annals of King Taejong," Year 13, early in the 5th lunar month. ^  Admiral Yi Soon-shin and the Turtle Ship. Retrieved 2006-01-11.

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