New Video Tells Baltic Ace Wreck Removal Story
The car carrier Baltic Ace collided with the container ship Corvus J and sank about 50 nautical miles west of Rotterdam in 2012, and SMIT Salvage, a subsidiary of Royal Boskalis Westminster, has released an extended video on the subsequent wreck removal operation.
The Baltic Ace sank within 15 minutes, resulting in the loss of 11 crewmembers. She was carrying 1,400 cars and sank with 540,000 liters of oil at the time and came to rest on her side at a depth of 35 meters and only 10-12 meters from the surface.
The Dutch Ministry for Infrastructure and the Environment, Rijkswaterstaat, contracted Boskalis and its partner Mammoet Salvage for the wreck removal operation. The salvage began in May 2014 and was completed in October 2015.
Around 13,000 tonnes of metal and 460,000 liters of fuel were removed from the wreck. The salvors used hot tapping to remove the fuel with a methodology and heating system developed to remove fuel from the tanker Kyung Shin which sank in Korea in 2010 and from the Costa Concordia that ran aground off the coast of the Italian island Giglio in 2012.
The oil is heated with inserts in the bunker tank. Steam is run through these inserts, which are cylinders of two meters long and 30 cm in diameter. The steam plant was installed on a barge and provided constant heating to create the flow of oil in the tank. The heating took 36 hours.
The wreck was then cut into eight pieces for removal. The same method was previously used in the salvage of MV Tricolor, a car carrier that sank in the English Channel in 2002 and the Russian submarine Kursk.
“Given a car carrier’s square shape, all the strength is in the lower deck up to around the 4thor 5th deck,” said Pieter van Vuuren, Operations Manager SMIT Salvage. “The new plan involved eight sections instead. We would lift the keel up to deck 4 and then use the wreck grab for the upper decks and smaller parts on the seabed.
“For the cutting spread, the Baltic Ace was slightly different to the Tricolor when a jack-up barge was used. This time, we wanted to use barges with a heave compensation system. The pre-tensioned saw-wire (80 meters-120 meters), which has steel ‘bushes’ — with sharp bits of hard metal on the outside — along it, is pulled up and down by wire winches between the barges.
“Mammoet has developed an in-house horizontal drilling system and after drilling they pulled the wire underneath the wreck. In a constant hauling and heaving motion, it took 30 hours for each cut. We started in April 2015 and by the end of May, the vessel was cut into eight sections.”
“By using the floating barges for cutting the wreck, we are reinventing the principles and developing an automated cutting process. This really shows our collective expertise and how we can draw on synergies from different parts of the Boskalis group. For example, the heave compensation system was designed based on a system used for dredging and now it has been introduced into the salvage arena.”
The project was completed several months before deadline.
Baltic Ace General Characteristics
Type: Car carrier
Tonnage: 23,498 GT, 7,787 DWT
Length: 148.0 m (486 ft)
Beam: 25.03 m (82 ft)
Draft: 7.9 m (26 ft)
Depth: 11.8 m (39 ft) (main deck), 25.20 m (83 ft) (upper deck)
Decks: Six fixed, two hoistable
Ramps: Stern ramp and stern quarter ramp
Ice class: 1A
Installed power: MAN-B&W 7S46MC-C (9,170 kW)
Propulsion: Single shaft; fixed-pitch propeller, bow and stern thrusters
Speed: 18.9 knots (35.0 km/h; 21.7 mph)
Capacity: 2,132 cars