Why did ancient wooden ships not leak at sea? It's all thanks to this traditional sealing skill!

Since ancient times, China's shipbuilding industry has been very developed, and has made many proud achievements in ship design and construction. Today we will introduce a very important skill in the construction and maintenance of traditional wooden boats, which is the warship seam to prevent the hull from leaking.

Traditional wooden boats are made up of a large number of wooden planks connected together. There are many seams between the planks. If these gaps are not tightly sealed, water will seep into the hull through the gaps and cause the ship to sink.

Therefore, plugging seams and leaks was born almost at the same time as ships. Shipbuilders called the technology of filling the gaps in the hull planks "艌缝" , and the filling material used for this process was called "艌料". As early as the Sui Dynasty in China, 艌料 and 艌缝 technology had been quite mature.

Materials

There are two main types of battens. One is hemp board made of hemp silk, tung oil and lime. Shipbuilders along the coast of Fujian often use hemp board made of shell powder, tung oil and hemp silk. The other type of battens is made of tung oil and lime.

Hemp boards are mainly used to fill the wider gaps between wooden boards to ensure the watertightness of the ship; tarpaulin made of tung oil and lime is often used to seal nail holes and other small holes and gaps on the hull to prevent the iron nails from rusting.

Preparation of feedstock

There is a strict procedure for the preparation of limestone materials: first, filter the high-quality tung oil three times with gauze, then sift the fine lime three times with a sieve; mix the lime and tung oil in a specific proportion, stir and mix well, and finally pound the tung oil ash until it is soft and sticky.

After the wooden boat is built, the surface of the hull is planed and cleaned, and a specialized craftsman fills the gaps between the wood with hemp boards, tamping them down before applying tung oil putty on the gaps, scraping the sealing surface with tools, and removing excess putty. After the entire hull is finished with seams, the hull is brushed with tung oil, and the hull and the hull are integrated.

Traditional wooden boats generally need to be repaired every year. After removing the attachments on the bottom of the boat, the hull seams are repaired with tarpaulin and tung oil to make the hull seal more durable.