Explained: Indian Navy’s new aircraft carrier dry dockhttps://indianexpress.com/article/explained/explained-indian-navy-new-aircraft-carrier-dry-dock-6015976/

Explained: Indian Navy’s new aircraft carrier dry dock

A dry dock is essentially a berthing place in which the repair, refuelling and maintenance of a ship is carried out after dewatering the dock.

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The Indian Navy aircraft carrier dry dock will be commissioned on September 28. (Express Photo: Pradip Das)

What is the purpose of the Indian Navy’s aircraft carrier dry dock that will be inaugurated on September 28?

A dry dock is essentially a berthing place in which the repair, refuelling and maintenance of a ship is carried out after dewatering the dock. It entails maintenance work like removing heavy machinery which cannot be done while the ship sails on water. While the naval dockyard in Mumbai had three existing British era dry docks, it had none that could accommodate an aircraft carrier vessel. At 281 m long, 45 m wide and almost 17 m deep, the dimensions of the new state-of-the-art dry dock were modified to accommodate the INS Vikramaditya, the Indian Navy’s only aircraft carrier.

What are the state-of-the-art features of the new aircraft carrier dry dock?

Apart from its mammoth size, this dock has been described as an addition to the navy’s strategic assets because apart from berthing the aircraft carrier, the dry dock has three intermediate gates that can divide the dock across its length and accommodate two smaller vessels at the same time.

Naval officers said that naval ships may no longer have to queue up at private dry docking facilities which can reduce the turnaround time that ships spend dry docking, giving the Indian Navy control over the maintenance time taken by each ship docked here.

This also reduces the burden on the State exchequer since, estimates suggest, using private dry docking facilities could cost up to Rs 10 lakh a day depending on the ship and nature of works it required. In addition to the dock, the project also includes two wharves adding about a km of berthing space for naval ships. The dock can hold up to 200 million litres of water, it’s reinforced concrete dock floor can hold ships weighing up to 90,000 tonnes, it’s two equilibrium valves can fill it up in 90 minutes each and eight dewatering pumps can empty the dock in 2.5 hours. Mechanicals arms running on rails along the length of the dock provide access to all parts of docked ships. Earlier, this was done by erecting scaffoldings along the docked ship.

What were the challenges in the construction of the dock?

Constructed over a period of nine years at a cost of Rs 1000 crore, the modern dry dock was built 300 m into the sea with only its head on land. For building the 281 m long dock and the wharves on each of its sides, a coffer dam was built with 114 piles of steel and concrete to keep the water out while construction was carried out on the sea bed. The silt removed from the site was 2.23 lakh tonnes, enough to lay 90 football fields. The project required 8000 metric tonnes of steel and 5 metric tonnes of concrete, one-and-a-half times that used in Mumbai’s iconic Bandra-Worli sea link.