Boskalis Moves Turkey's Biggest Floating Drydock to NASSCO
When the Jones Act shipbuilder General Dynamics NASSCO ordered a new floating drydock from a shipbuilder in Turkey, it needed a way to move it across an ocean and around a continent. Luckily, there was an even larger floating drydock available to carry it: Boskalis' BOKA Vanguard, the largest semisubmersible heavy lift ship in the world.
General Dynamics brought in logistics giant Kuehne+Nagel to arrange the oversize shipment, including the technically demanding loadout process. The 17,000-tonne drydock would fit snugly on the Vanguard's 900-foot-long deck, but there would not be an abundance of room to spare.
“We had checklists. Then we had checklists for the checklists: every smallest detail accounted for, nothing left to chance,” said Aliye Erkan B?y?k, a logistics manager at Kuehne+Nagel's Istanbul office.
To position the drydock aboard the heavy lift ship, BOKA Vanguard needed to ballast down far enough that her main deck level was lower than the draft of the floating drydock, meaning deep water was a requirement. Once the drydock was clear of the pier at the shipyard, four tugs towed it out into open water to meet up with the heavy lift ship for loading. After positioning, BOKA Vanguard deballasted and the engineering team began carefully lashing the drydock to the deck.
The cargo, the largest floating drydock ever built in Turkey (Kuehne+Nagel)
BOKA Vanguard semi-submerged for loading (Boskalis / Kuehne+Nagel)
"The process of securing the drydock was not rushed and took several days: every centimeter, every millimeter had to be double-checked. We also had additional support boats on standby to shuttle crew and engineers between the port, the drydock, and the carrier ship," said Aliye.
When all was secured, BOKA Vanguard got under way from Turkey and headed for Cape Horn, bound for California. As of Thursday she was just outside of Punta Arenas.
BOKA Vanguard has been used as a simple floating drydock herself. In 2019, the cruise ship Carnival Vista had azipod issues that required out-of-water repairs, but the nearest shipyard (in the Bahamas) did not have an available dock. BOKA Vanguard took Carnival Vista aboard, lifted the cruise ship out of the water and transited to the shipyard, where yard staff made the repairs while the Vista was out of the water.
2013-built BOKA Vanguard is the world's biggest semisub heavy lift ship, by a wide margin. At 115,000 dwt and 900 feet in length, she is large enough to move some of the largest offshore rigs and floating production platforms. When submerged to the maximum depth possible for loading, BOKA Vanguard's keel sits more than 100 feet beneath the surface, making her (for brief periods) the deepest-draft merchant ship ever built.