Salvaging a thousand-year-old ship: A preservation journey full of unpredictable risks

Behind every salvaged ancient ship is a race against time, science and nature to preserve the fragile wooden artifacts that remain.

Ancient ships lying deep under the sea always have a strange attraction - they carry within them the story of time, of ancient stormy voyages. But for archaeologists, salvaging an ancient ship from the water is not only an act of opening up the past but also a "big gamble" in conservation science . Because just a small mistake, the entire wooden structure of the ship can collapse or be permanently damaged when exposed to air.

In the seawater environment, especially under layers of mud or sand, wooden blocks are preserved in an almost anaerobic state - where organic decomposition microorganisms cannot be active. That is why many ships can exist for hundreds of years on the seabed while still maintaining their relative shape. However, when salvaged, the structure immediately falls into a state of imbalance. Water fills the wood fibers, acting as a supporting frame. Once the water is drained, the capillaries in the wood collapse, causing the wood to shrink, crack and deform in just a few days. That is why, in the world , many ancient ships have been seriously damaged immediately after being brought ashore, despite the best efforts of experts. The salvage of ancient ships underwater must be carried out in a very scientific and meticulous manner.

The Swedish ship Vasa. Photo: The Seattle Times.

The most famous story is the Swedish ship Vasa — a warship that sank in 1628 and was raised in 1961. After being brought ashore, the ship was placed in a special environment and spent more than 20 years being sprayed with the chemical Polyethylene Glycol (PEG) to replace the water in the wood. Although considered the most successful in the history of ancient ship conservation, the Vasa’s maintenance costs still cost millions of dollars each year, and experts still worry about the risk of the wood being weakened by the slow chemical reaction. Another example is the British ship Mary Rose, raised in 1982, which also required more than 30 years of treatment and maintenance in a controlled environment before being put on display.

These cases show that preserving ancient ships is not only a technical issue, but also a financial, infrastructure and time challenge. An international standard process usually involves several stages: 3D underwater survey, structural stabilization, maintaining stable humidity during the salvage process, and then chemical treatment that lasts for decades. PEG is a popular material, but many countries are now experimenting with alternative methods such as lactitol or freeze-drying technology to reduce costs and increase material durability.

Ancient ship recently discovered in Hoi An. Photo: Hoai Van / Tien Phong Newspaper.

In Vietnam, the discoveries of ancient ships in Quang Ngai, Binh Thuan , Cu Lao Cham or most recently Hoi An all show great potential for marine archaeology. However, the conditions for preservation after excavation are still weak points. The hot and humid climate, limited preservation facilities and lack of environmental control equipment make it difficult to maintain the integrity of ancient timber. In fact, many pieces of wood or structural details of ancient ships have deteriorated rapidly after being brought out of the water, despite being covered, sprayed with moisture and temporarily treated.

Domestic experts still advocate caution: Salvage should only be done when conditions for long-term preservation are met. Otherwise, leaving the ship to continue “sleeping” under the sand and seawater is sometimes the best solution, because the natural environment is the most effective layer of protection for relics. This approach is similar to the in situ preservation trend encouraged by UNESCO, which prioritizes research, modeling, and remote monitoring instead of hasty excavation.

With the ancient ship recently discovered in Hoi An, the issue of preservation is being carefully addressed. A full salvage can only be done with adequate technology and resources — something that even many developed countries have to consider carefully.

Salvaging an ancient ship, therefore, is not simply “bringing the past ashore” but entering a long-term, costly and highly risky preservation process. Every decision is a matter of life and death for the heritage. The ships currently buried under the water and sand of the East Sea are both treasures waiting to be discovered and a reminder that science must sometimes stop before the fragility of thousand-year memories.

After storm No. 13, a thick layer of sand along the coast was washed away, revealing the shape of a wooden ship suspected to be an ancient ship tens of meters long at Tan Thanh beach, Hoi An Tay ward (Da Nang city). The ship lies parallel to the shore, many parts of the structure are still intact, attracting the attention of locals and tourists. According to initial assessment, the ship dates back to around the 14th-16th century, the structure shows the intersection between Southeast Asian and East Asian shipbuilding styles, and is considered one of the few ancient ships that are still quite intact ever discovered in Vietnam.

Source: https://khoahocdoisong.vn/truc-vot-tau-co-nghin-nam-hanh-trinh-bao-ton-day-rui-ro-kho-luong-post2149067623.html