#千万IP创科学普# The secret of maritime safety, Fuchuan will tell you

The manufacturing technology of Chinese watertight bulkhead Fuzhou ship

The watertight compartment structure model of the Fuzhou ship

Image source: Quanzhou Overseas Transportation History Museum

The watertight bulkhead technology is the most critical part of the construction of the Fuzhou ship. It uses bulkheads to divide the cabin into different compartments that are impermeable to each other, ensuring that the ship can still maintain buoyancy when damaged, greatly improving the safety of navigation. The invention of the watertight bulkhead technology played a positive role in the prosperity of the Quanzhou Maritime Silk Road during the Song and Yuan dynasties.

During the Song and Yuan Dynasties, Chinese ocean-going wooden sailing ships were favored by merchants and envoys from various countries. The important reason was that Chinese sailing ships adopted a unique watertight bulkhead structure, which enhanced the safety of ship navigation. Quanzhou's maritime transportation was developed early, and the shipbuilding industry was developed. Quanzhou Port (Zitong Port) during the Song and Yuan Dynasties was known as the "largest port in the East". According to "Wang Yao's Boat Building" in "Xishan Magazine" written by Cai Yongjian during the Jiaqing period of the Qing Dynasty: "In the Tianbao period, Wang Yao transported wood from Borne to build a boat for Lin Luan. The boat was 18 zhang long, about 42 zhang wide, more than 45 zhang high, and 2 zhang wide at the bottom, with a pointed round shape. The mast was more than 10 zhang high. The silver-inlaid cabin side had 15 compartments, which could store as much as 30,000 to 40,000 dan of goods." This historical material records the situation of the seagoing ships built in Quanzhou during the Tianbao period of the Tang Dynasty, in which "15 compartments" refers to 15 bulkheads. This is the earliest record of the use of bulkheads in seagoing ships in the Quanzhou area.

Digital outline of a Song Dynasty ship in Quanzhou

Image source: Quanzhou Overseas Transportation History Museum

In 1974, the wreckage of a Song Dynasty ocean-going cargo ship was unearthed at Houzhu Port in Quanzhou Bay. Its cabins were well preserved and had a very complete watertight compartment structure.

The watertight bulkhead structure was also found in the ancient Song Dynasty ship in Fashi, Quanzhou, which was excavated in 1982. The excavation of the above two ancient ships has irrefutably proved that at least in the Song Dynasty, the seagoing ships built in Quanzhou had adopted a mature watertight bulkhead structure.

The excavation site of Song Dynasty ships in Quanzhou Bay in 1974

Image source: Quanzhou Overseas Transportation History Museum

The so-called watertight bulkheads are independent and watertight compartments separated by bulkheads in the cabin. As for a single watertight bulkhead, it is surrounded by bulkheads, hull plates, bottom plates and ship decks, forming a relatively independent space.

The position of the bulkhead and the size of the compartment are closely related to the purpose of the compartment. The bulkhead is generally set at the inflection point of the hull plate to support the hull plate, thereby increasing the strength and rigidity of the hull. For the entire wooden sailing ship, the number of watertight compartments is related to the size and purpose of the ship. The larger the ship, the more compartments it has. Passenger-oriented ships have more watertight compartments than cargo ships.

The watertight bulkhead structure of the Fuzhou ship (ribs, bulkheads, mast bases, etc. are shown in the picture)

Image source: Quanzhou Overseas Transportation History Museum

The watertight bulkhead shipbuilding technology in the construction process of wooden sailing ships includes basic contents such as ship design, material selection, and construction technology.

Ship designs are usually made on-site by shipbuilders based on their own experience and construction methods passed down from generation to generation, without precise data or drawings.

The materials selected are generally camphor wood and fir wood. Camphor wood is more resistant to nails (the wood is not easy to crack after the nails are nailed in), while fir wood is relatively light.

The traditional construction technology in Quanzhou is called the "hull method". The first step is to install the keel and nail the keel wing plate, then nail part of the bottom plate, install the bulkhead plate, nail the bilge plate, put the boat on the fastener, install the beam arch, and finally lay the ribs at the connection between the bulkhead plate and the hull plate, and nail the other bottom plates.

After the main structure of the hull is completed, the deck work will be done. While the outer shell is being completed, the cabin seams are also completed at the same time. The mast and sails are done last, followed by the exterior painting.

The longevity hole at the keel connection of Quanzhou Fuchuan

Shipbuilding Timber

Image source: Quanzhou Overseas Transportation History Museum

There is also a set of traditional rituals and taboos in the shipbuilding process. The modern shipbuilding process is called "structural method".

In 2007, the "Princess Taiping", an imitation of an ancient wooden sailing ship from the Ming Dynasty, was built under the leadership of the 60-year-old shipbuilder Chen Fangcai. From the ship design, material selection, construction technology to exterior painting, and even the various rituals during the construction process, all followed tradition.

The ship has 14 bulkheads, dividing the ship into 15 cabins. There are two water holes under the bulkheads near the keel. The gaps between the boards in each bulkhead are sealed with tung oil putty and hemp rope to ensure watertightness.

Schematic diagram of the Princess Taiping

Image source: China Maritime Museum

The watertight bulkhead Fujian shipbuilding technique was a major invention in China's shipbuilding during the Tang Dynasty. After the Song Dynasty, it was widely used in seagoing vessels and also in some inland river vessels.

It was introduced to the West by the Italian traveler Marco Polo as early as the end of the 13th century. 500 years later, in 1795, General Samuel Bentham, chief engineer of the British Navy, was commissioned by the British Royal Navy to use the watertight bulkhead technology pioneered by the Chinese for the first time to build a new type of warship.

The invention of the watertight bulkhead Fuzhou ship manufacturing technology is a major contribution of China to the world's maritime history. The watertight bulkhead structure plays an important role and value in improving the safety of ship navigation, facilitating cargo compartment management, increasing the strength and rigidity of the hull, and serving as a support point for the bending of the hull plate.

After the Song Dynasty, watertight bulkhead technology was gradually widely adopted by the shipbuilding industry in various countries in the world. To this day, this technological invention is still an important structural form in ship design. This traditional watertight bulkhead shipbuilding technology is still preserved in the coastal areas of Quanzhou, which has had an important impact on the development of human maritime history.

The "Watertight Bulkhead Fuzhou Ship Manufacturing Technique" was included in the second batch of national intangible cultural heritage protection list in 2008. In September 2009, it was bundled as "China's Watertight Bulkhead Fuzhou Ship Manufacturing Technique" and selected into the UNESCO "List of Intangible Cultural Heritage in Need of Urgent Protection".