Turtle ships had distinct defensive and mobile forms, study finds

A recent academic report challenges long-held views on the iconic Korean "turtle ship" (Geobukseon), proposing that these formidable warships existed in two distinct variations tailored for different combat roles. The study, published by the National Maritime Heritage Institute, suggests one type prioritized defense and stability, while the other focused on mobility and battlefield adaptability.

Researchers meticulously examined historical documents, including the "Yi Chungmu-gong Jeonseo" from 1795, focusing on two specific turtle ships: the Tongjeyeong Geobukseon and the Jeollajwasuyeong Geobukseon. While the existence of multiple turtle ship designs was known, this marks the first comprehensive engineering analysis differentiating them as independent entities.

The Tongjeyeong Geobukseon, associated with the central naval command, is characterized as a "defense-first" model. Its design featured a covered deck (gaepanseon) without openings, maximizing its protective capabilities. In contrast, the Jeollajwasuyeong Geobukseon is described as a "mobile and field operation" type, featuring semi-hexagonal openings on its deck and lacking a mast, which would have allowed for better observation and command in close combat.

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The turtle ship was a variable combat platform, varied on a common shipbuilding technology.

Further analysis revealed differences in the ships' prows, or "turtle heads." The Tongjeyeong type likely housed a cannon for frontal assault, whereas the Jeollajwasuyeong type may have been designed to accommodate devices that emitted fire and smoke. The researchers attribute these variations to the distinct tactical environments faced by different naval squadrons.

The study also re-evaluates the physical structure of the turtle ship, questioning the traditional depiction of a completely flat bottom. The new findings suggest a curved hull shape, particularly at the bow and stern, which would have allowed for a more natural fit with the wooden planks and improved stability. Additionally, the report proposes that the openings on the deck served as "observation windows" for command, and the stern plates were equipped for firing medium cannons, indicating a dual defensive and offensive role. The research combined historical text analysis with 3D modeling and scaled model experiments.

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The conclusion is based not only on literature but also on actually building and sailing a ship.