On April 24, 1961, the warship Vaasa broke the sea surface for the first time in 333 years. A salvage prepared for five years. Here is the story of how cooperation and innovative power – and both hard and dangerous work – lifted the shipwreck from its cradle of mud 32 meters below sea level.
In the black and white journal film from SVT, Anders Franzén, noticeably taken by the moment, stands on what remains of Vaasa’s dark wooden deck that is still dripping with water. When he grabs the TV reporter’s microphone, which goes around between the group of zealots on deck who together made the rescue possible, he has gathered:
“It’s a strange feeling to be standing here in the middle of the early 17th century. But if we ignore the emotional, it has gone as we have planned since 1956. ”
The plug was the beginning
1956 was the year when the engineer and private researcher Franzén lowered the plug plow from the boat just outside Beckholmen in Stockholm. Right here, towing from different directions had clearly shown that there was something big at the bottom, and the hope after reviewing documentation of the sinking was that this big one would be Vaasa.
The plug went down into the depths and came back up with a piece of wood. Svartek, it would turn out: the type of wood that the ship was made of and which has turned black and become a little oily from many years on the seabed. Another sample was taken 20 meters from the first, to confirm that it was a large wooden object. The hope was aroused, and within a month the divers Per Edvin Fälting and Sven Persson went down into the pitch black depths. Once at the site, Fälting put his hands on a hull with large square gates, he climbed up a bit and felt another row of gates. There was only one sunken ship with two battery decks in the port of Stockholm. Anders Franzén’s three-year search for Vaasa was over.
The key person Anders Franzén’s knowledge as an engineer was important in the work to find the warship, but the most important thing was his ability to make important contacts, states Fred Hocker who is research leader at the Vasa Museum in Stockholm.
– He got others to get involved in the rescue, for free. Among the first steps was to get an infrastructure for the entire project by creating the Wasanämnden, which would, among other things, answer the question: Is it even possible to salvage the ship?
Freeze in ice cubes?
A period of investigation followed, where some of the more memorable proposals to salvage the ship were to freeze it in a giant block of ice, or fill it with ping pong balls. The latter would also require about a billion ping pong balls and a ship that, unlike Vaasa, was completely tight, Fred Hocker points out.
The solution to be able to lift the ship in a cohesive condition and to get some of the suction power from the clay to release was to dig tunnels under its hull. Calculations showed that it took six tunnels under the ship to get an even lift. And the only way to do this was by using divers who dug the tunnels with a specially developed high-pressure sprayer. This is where the Navy came into the picture. The Armed Forces decided that all training of their own divers would take place via the work with the tunnel excavation under Vaasa.
– Insane, some divers liked to dig under the hull. But it was the method that was available without damaging the ship. For two years, the divers worked to dig in first from one direction, and then the other. It was glacial clay, ie blue clay, and bottom sediment. The ship rested in the mud, but near the bedrock at a point below the port side, near the bow.
When the tunnels were finally completed, the actual movement of the ship towards Kastellholmen began. A challenge in itself was to calculate how much lifting force was required to lift both the weight of the ship itself, and the lifting force required to make it come loose from the grip of three meters of mud.
– The actual lifting force required for both the ship’s weight and for the suction power from the clay was about 600 tons.
Odin and Frigg
The two pontoon ships Oden and Frigg were placed on opposite sides of the wreck, the steel wires were connected and the lifting began by the pontoons being gradually emptied of water.
– The hull came loose very softly from the bottom clay, and the first lift had succeeded, says Fred Hocker.
The 18 stages required to move the ship brought with it a lot of corrections of the steel wires, which began to slide along the hull. At one point, the ship also got stuck in the bottom cushion and had to be turned around, a job that in itself requires several lifts.
When Vaasa was finally ready outside Kastellholmen, the bearing entered the next phase. Here was the great challenge, with the limited knowledge of the time, to research how it would affect the ship’s hull to meet oxygen-rich air again after 333 years, and how the ship would be held together when the water pressure released. At the same time, a year and a half of work began under the water surface to seal the holes in the hull, including building for the stern castle that had come loose.
On Monday, April 24, 1961, the rocks on Kastellholmen were filled with spectators. TV cameras were set up for the first ever European live broadcast from Sweden. In the water below the cliffs, the lift began with the water flowing out of the pontoon ships’ bilge pumps. The hydraulic winches that lifted the ship were started and the steel wires began to roll up. So the surface of the ship’s black oak logs was broken. Bilge pumps were connected to empty the ship of water and thus give it its own buoyancy.
– The oldest ship in the world to float for its own hull, 333 years after the sinking, says Fred Hocker.
Another chapter in Vasa’s salvage began when the ship was moved to the pressure-relieving cradle prepared in the Gustaf V dock on Beckholmen. It took six months for twelve archaeologists to take care of all the objects on board. At the same time, bottom sediment and clay were pumped up through a special strainer that captured smaller artifacts. The fact that the work had to go so fast was a consequence of the uncertainty that existed about how the hull would hold together after bearing, with the heavy load of clay and furniture it contained.
– In addition, the knowledge about the decomposition process of the wood was not so great at this time, there was an uncertainty about what would happen after the hull came in contact with oxygen and with the pressure change that occurred. During the work in the dock, the ship was rinsed with water, both by hand and via special sprinklers.
Now, 60 years after Vaasa broke the water surface, intensive research and conservation efforts have led to answers to many questions. One can feel particularly exciting to ask even in the present:
Would the salvage have looked different if it had taken place today?
– Basically no. There is no better way to salvage a ship intact than this. What we could have done differently with the better analysis tools we have today to examine the condition of the ship, would have been to design a lifting device – a pressure-relieving shape or cradle – that was more specifically designed for the ship. But we can see that the bearing method used led to very little damage to the hull, says Fred Hocker.
Facts: The sinking of the vase
Gustav II Adolf’s prestigious building Vaasa was launched in the spring of 1627, 69 meters long and over 50 meters high measured to the top of the mainmast. But already early on, the fact is demonstrated that the ship was built too high for underwater carrying capacity: in a test, thirty men ran from one side of the ship to the other when she was moored at the Ship Bridge. Vasa tilts so much that the test had to be canceled.
1,300 meters was the maiden voyage. Then the ship is caught by a gust of wind which causes it to tilt sharply to the side. Water rushes in through the cannon gates and the ship goes to the bottom.
Facts: The map that revealed Vaasa
In the winter of 1955–56, the marine engineer and private researcher Anders Franzén received a new map of the harbor between Tegelviken and Beckholmen, which the city of Stockholm had produced in connection with the plans for a new bypass with a bridge over Strömmen.
The city had made a number of explorations and during these found an elevation on the seabed, about 120 meters from the shoreline, which was about 50 meters long and 6 meters high.
“The blast from the construction of the Gustaf V-doll” was the answer he got when asked what it could be. But even here, the cooperation between the group of zealots who worked with the salvage of Vaasa played a big role, when the diving base Per Edvin Fälting knew that the blasting stone had been placed elsewhere. And that this could very well be just the sunken ship. Which it turned out to be at a later sampling.