The turtle ship has been credited as being the first more or less iron clad ship in the world.
Sources indicate that sharp iron spikes protruded from hexagonal plates covering the top of the turtle ship. While it is clear from the available sources that the roof of the ship was covered with iron spikes to prevent boarding, there is insufficient evidence to support the claim that it was iron plated.
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 two 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 (some would use special wooden bolts several feet in length, with specially engineered iron fins).
An advantage of the closed deck was that it protected the Korean sailors and marines from small arms and incendiary fire. The spikes discouraged Japanese sailors from engaging in their primary method of naval combat at the time, grappling an enemy ship with hooks and then boarding it to engage in hand-to-hand combat.
Spikes on the deck.
The Turtle ship was a heavy invincible Korean battle ship. Sources indicate that sharp iron spikes protruded from hexagonal plates covering the top of the turtle ship.
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, and other minor modifications.
Class: Panokseon Length: 100-120 ft Beam: 30-40 ft Propulsion: 80 oarsmen 50 soldiers Armament: sulphur gas thrower, iron spikes (deck) 11 cannons. (range 200- 600 yards)