Turtle Ships: Korea’s Ultimate Naval Weapon

Key Point: Turtle Ships were naval vessels used by the Korean navy during the Joseon Dynasty. They were characterized by a unique design, which made them resemble a turtle.

Ever wondered what are turtle ships, and how they were used in naval battles? Well, in this article I aim to give you an answer to that and more. You will see everything there is to know about turtle ships, including how effective they really were and why played an important part in saving Korea from an invading army.

Now, before we move on, let’s establish a few things first. Mainly, what are turtle ships?

Turtle Ships were a type of naval vessel used by the Korean navy during the Joseon Dynasty. They were characterized by a unique design, which included a covering of iron plates shaped like the shell of a turtle. These ships were primarily used for naval warfare, as their armor made them difficult to sink and provided protection for the crew. They played a massive role in defending Korea against Japanese invasions in the late 16th century.

So, that was the short summary of this article. Now it’s time we go into a little more detail. This means we will be starting of course with the history and origin of turtle ships. Let’s explore that in this next segment.

History And Origin Of Turtle Ships

The origin of turtle ships or “Geobukseon” can be traced back to the early 15th century. So, why were they built? Well, back then Korea had an issue with Japanese “pirate” ships raiding up and down their coasts.

So, during the reign of King Sejong the Great, the first predecessors of turtle ships were commissioned to defend Korea from pirate raiders. These early versions were “ironclad”. This means they were fortified or strengthened against fire attacks and cannon fire with iron armor.

These were the first forerunners of turtle ships as we know them today. But the design we all know today came about in the late 16th century. During the Japanese invasion of Korea. At Korea’s darkest hour, their national hero Admiral Yi led the first ships with the distinct “turtle” design and characteristics.

And as stated in this book: “The customarily modest Admiral Yi Sun-sin would never have claimed to have been the inventor of the turtle ship, a role with which he is traditionally credited”

When Were They First Used?

The first recorded use of the Turtle Ship was in 1592, during the Battle of Okpo. This is where a fleet of turtle ships under the command of Admiral Yi destroyed a portion of the Japanese fleet they encountered.

Now, let’s move and examine the dimensions. Meaning the size of an average turtle ship more closely.

Dimension And Design Of Turtle Ships

The dimensions of average turtle ships were:

Length: 140 feet Width: 30-40 feet

Displacement: 300 – 400 tons

As you can see it was a rather heavy ship. All the weight from the iron armor and weaponry really shows.

Their Appearance

A turtle ship

An average turtle ship had two masts on top of a deck that was covered with iron armor. The armor offered the ship protection from cannon and small arm fire. The armor was also covered with spikes to prevent any enemy soldiers from boarding the ship.

Back then the favorite naval tactic of the Japanese was to ram and board an enemy ship. Given how skilled they were in hand-to-hand combat it makes sense they chose this route. So the Koreans were having no one of that and placed iron spikes on the iron armor, which negated that tactic.

The bow of the ship usually had a giant dragon head. This wasn’t just for show, since the dragon head could also fit a cannon inside. But in some versions, they burned flammable materials and allowed smoke to go through the dragon’s head which lead to the ships creating their own smoke screen as they passed.

What Weapons Did The Turtle Ship Carry?

Let’s first start with the personnel. The ship carried 70 oarsmen and up to 50 marines. Turtle ships usually had around 25 cannons on them, spread out on the port and starboard side, with 2 cannons pointing forward from the bow of the ship.

The 4-Types Of Cannons The Koreans Used At Sea

A little-known fact is that the Koreans were actually very skillful in the production and use of cannons. They typically used 4 types at sea:

Cannons used on turtle ships
  1. Cheonja (range 1200m)
  2. Jija (range 1000m)
  3. Hyeonja (range 800m – 1500m)
  4. Hwangya (range 1100m)

Let’s now take a look at how these weapons on board were used.

Turtle Ship Tactics Explained

There were 6 tactics naval commanders used when deploying turtle ships. And they were:
1. Anchoring in a strategic position
2. Engaging in hit-and-run
3. Firing cannons from a distance
4. Luring the enemy into a trap
5. Boarding enemy vessels
6. Attacking at night

Now, let’s take a look at each of the turtle ship tactics in a little more detail.

Anchoring In A Strategic Position

This is a tactic where the commander of turtle ships anchors the ships in a favorable position. Such as a narrow strait. or a bay. The main purpose of that was to limit the enemy’s ability to maneuver and basically make the enemy sitting ducks. If the enemy can’t move, they are easier to hit.

Engaging In Hit And Run

Accompanying ships to the turtle ships were used to engage the enemy and run away. As the enemy ships chased the smaller ships they were then attacked by the turtle ships that were waiting for them some distance away.

Firing Cannons From A Distance

This one is simple. They lined up a good distance from the enemy and opened fire. Pretty straightforward.

Luring The Enemy Into A Trap

The turtle ship would lure the enemy into a narrow passage or another confined area, making it easier to target and destroy the enemy.

Boarding Enemy Ships

Despite being relatively closed off the turtle ship was capable of boarding and capturing enemy ships. That’s where those 50 marines on board came in handy.

Attacking At Night

This one used the element of surprise. The turtle ships simply opened fire at the enemy at night.

Those were the six tactics turtle ship commanders used to beat their enemies. Now, given how powerful these ships were, were there any downsides to turtle ships? Yes, there were. Let’s check them out.

Disadvantages Of Turtle Ships

The turtle ships had a few disadvantages. The main one was its high cost of production. The unique design and more importantly the armor made the cost of each turtle ship very high. They were very expensive so the Koreans were averse to the risk of losing any of them.

The other thing the armor caused, aside from the high cost was the reduction in speed. Despite it having 2 masts and around 70 oarsmen powering it, the added weight limited its speed.

Despite these two main disadvantages, it was still a powerful ship. But if it was that powerful, then why did it stop being used?

Why Did The Turtle Ship Fell Out Of Use?

Well, for a couple of factors. It comes back to the high cost. The high cost of the ship prevented the design from spreading outside of Korea. And it also meant that as soon as more advanced ships came along (mainly from European powers) the turtle ship became an obsolete and expensive weapon.

Hence why it died out. It was too expensive and became obsolete as soon as more maneuverable ships with better ranges came along.

In Conclusion

Thank you for taking the time to read this article. I hope you learned a thing or two. If you wish to continue learning about naval weapons used in the “Age of Sail” I suggest taking a look at my article on fireships right here.

Or take a look at my article on the hand-held weapon sued by sailors for centuries during the “Age of Sail”. Do you know which one it is? Alright, I will tell you it’s the cutlass. See more, right here.

Take care!

Sources: Fighting Ships of the Far East, Vol. 2: Japan and Korea, AD 612-1639