Korean Turtle Ships

a.k.a. Geobukseon or Kobukson Class of Ship

The vessel pictured above is a 1:2.5 scale reproduction of a turtle ship housed in the War Memorial Museum, Seoul Korea. This is regarded the most historically accurate reproduction of such a vessel.


Originally developed in 1413 the kobukson, or 'turtle ship', began as an updated version of the kwason, or 'spear ship' (designed for ramming enemy vessels in combat). The turtle ship is probably the most famous class of vessel to exist in Korean naval history. However, the initial design of this craft only generally resembles that of those built later in the 16th century which culminated in the famous battleships of 1592.

As is common for most famous weapons systems the turtle ship did not suddenly emerge, but rather evolved from earlier and less refined designs. The immediate ancestor of the turtle ship was the p'anokson which functioned as the workhorse of the Korean navy both before and throughout the time of the turtle ship (normally outnumbering the turtle ships in combat). It's most noteworthy features are that it has two decks, an upper deck where troops would be stationed and an enclosed lower deck to protect the oarsmen in combat; a 'castle' situated centrally on the upper deck, used as a command and observation post by the captain; and high sides designed to repel boarders. This last point is significant as the Japanese, Korea's long-term and primary naval adversary, would typically attack an enemy ship by boarding it.

Following on from the p'anokson the original turtle ships featured high sides and two separate decks. However, they typically omitted the inclusion of a 'castle' and were originally designed with the emphasis of being able to be used to ram and damage an opponent's ship without suffering damage themselves. Because of this they were boxy and very solidly constructed, as has been historically typical of Korean warships, but even more so in this case.

This design was taken to its ultimate conclusion in the 16th century by the legendary Korean naval figure, Admiral Yi. These improvements included a completely enclosed and overhung upper deck. This was shared by the gunners and oarsmen and was covered over by a sturdy, curved, roof. Armoured plates to which spikes had been attached would form an outer skin making this roof both tough and practically impossible to walk across. As a final touch these spikes would often be obscured by straw or mats to lure in unsuspecting boarders.

On the sides of the upper deck gun ports were positioned, allowing the firing of cannon or for use by archers. There were also additional ports at the bow and stern of the ship.

While the open decked p'anokson made an ideal platform for carrying out remote bombardment the advanced turtle ships of the 16th century were best suited to rapidly moving in to engage enemy vessels up close and break up enemy lines before quickly withdrawing. While turtle ships of this vintage were still occasionally used to ram enemy ships they were now generally seen as too valuable to risk in a collision with another ship. Also despite their power and their fame it was uncommon for more than five of these vessels to see action in any one battle.

Following the transmission of gunpowder technology from Ming dynasty China in 1373 the Koreans rapidly developed a highly advanced range of naval artillery. By 1410 it was common for their ships to be armed with a variety of cannon with records showing that at this time they possessed 160 ships of war with artillery on board. This marked a turning point where the Koreans began to favour an approach similar to that of the Chinese. This emphasised the bombardment of enemy vessels rather than attacking by ramming or boarding them.

These weapons included deck mounted mortars which fired the Korean version of Chinese 'thunder-crash' bombs - a hard-cased fragmentation projectile. They also used four classes of commonly used cannon, as distinguished by their size, which were typically mounted on mobile wooden carriages (as shown below).

While these cannon would fire stone or iron balls, the preferred projectile weapon used by the Koreans at this time was a giant arrow with an iron tip and iron or leather fins (shown right). While these may look like rockets they were not self-propelled but rather fired from a cannon. The largest of these measured up to nine feet (around three metres) long. These projectiles possessed both a longer range and greater accuracy than ball shot but had equivalent destructive power.

They also had the advantages that upon impact they would both damage the ship and also often shatter, spraying deadly splinters of wood among the crew of the ship they hit. As well as this, they could be easily converted into fire arrows. Turtle ships would typically be armed with a full range of normal cannon, firing both ball and arrow projectiles, as well as being crewed by a number of archers.

References:
Fighting Ships of the Far East (2) by S. Turnbull. Osprey Press, 2003.

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