Shipyards are not just busy with meeting delivery deadline for newbuildings, but are constructing dry docks on a massive sale. The huge demand for repair and maintenance will see even more number of shipyards jumping into the dry dock bandwagon, writes Manoj Kumar.

Two of India’s top shipyards are building dry docks with an eye on the maintenance requirements of ships sailing on the international route between Dubai and Colombo. Pipavav Shipyard (PSL) is on course to set up a dry dock, which will be the world’s biggest dock for repair and maintenance of vessels operating in the region surrounding Gujarat coast. The dry dock, roughly the size of seven soccer fields, will be larger than the world’s largest dry-dock at Ulsan, South Korea, which is 490m long, 115m across and 13.5m deep, owned by Hyundai. The work on Pipavav’s new dry dock , which is about 680m in length, is expected to begin in a couple of months and may cost over Rs 1,000 crore, it is learnt.
Cochin Shipyard, India’s largest state-run shipbuilder, also has charted out plans for a new dry dock in order to boost capacity. The Kerala-based shipyard is in talks with prospective partners in the defence sector to jointly construct the dry dock. It will share the cost of building the new dry dock in equal proportion with its proposed partner. Cochin Shipyard is planning is planning to list on the stock exchanges to mobilise its share of funds. The government is planning to sell around 15% of Cochin Shipyard’s shares through IPO. This includes a fresh issue of some 24 crore shares having a face value of Rs10 apiece. Cochin Shipyard is the first public sector shipbuilder to be listed on stock exchanges. “There are lot of synergies when you have a business partner,” V Kala, company secretary and public information officer at Cochin Shipyard, said recently.

Types of dry docks

Graving Dock
A graving dock is a channel cut out of a basin or river in which a caisson is placed in front of the opening and water is pumped out. As the water is pumped out the ship is lowered on to the blocks. This type of dock can handle the largest of vessels.

Marine Railway
This type of dock has blocks mounted on a skid and the skid is lowered into the water on rails. The ship is positioned and chains or line haul up the skid with the vessel on the blocks. In the past horses were used to power these railways. These railways typically do not have as much lifting power as a graving dock or a floating dry dock.







Floating Dry Dock
This type of dock is U-Shaped and can be sunk to allow the vessel to enter and be positioned. When the ship is in position the water in the ballast tanks of the dock is pumped out and the dock rises to meet the ship. Then the ship is lifted out of the water by the upward motion of the dock. This type of dock typically can lift heavier ships than the railway but not as heavy as a graving dock. The benefits of this dock are that it can be towed anywhere in the world and that it can be ballasted to lift a damaged ship with an excessive list or trim.

Travel Lift
This system is for smaller vessels and tug boats. The travel lift incorporates a series of straps which are passed under the boat to lift it out of the water. Then the boat and travel lift can be driven to a place on land where the boat can be set on blocks. This system benefits in that no vessels will tie up your hauling machinery. Work does not have to be performed while the boat is in the lift as with the other docking methods.

A dry dock is a flooded basin where a ship to be sailed in and then drained so that the ship will rest on a dry platform. Dry docks are used for construction, maintenance and repair of ships. Some dry docks are designed mainly for ship construction whereas others are intended for repairs and maintenance.
Dry docks usually cost around Rs1,000 crore to build from scratch. Ships are required to be drydocked twice every five years to ensure their seaworthiness. Ships carry a docking plan which specifies where the wooden blocks are to be placed, the angle of the side blocks, and the height of the side blocks. It also lists where its parts such as transducers, sea chests, and tailshafts are to be located. Ships are sometimes allowed to postpone or waive off drydocking by having an underwater inspection done instead of drydocking.
Pipavav Shipyard is planning to raise its capability to build and repair (dry dock & afloat) most kinds of commercial dry and liquid cargo ships such as very large crude carriers (VLCCs), capsize bulk carriers, Suezmax, Aframax, Panamax, container ships, chemical tankers, dredgers, platform supply vessels and anchor handling tugs. The company’s order book currently stands at over Rs 7,000 crore.
“Ship repair and maintenance is a huge business opportunity for us. We will soon be converting our existing wet dock into a dry dock which, at about 680m, will be the biggest dry dock in the world,” Nikhil Gandhi, group chairman, was quoted in a section of the media recently. Pipavav Shipyard has also forayed into defence sector when it recently received orders worth Rs 2,600 crore for building off-shore patrol vessels for the Indian Navy.
“Over 15,000 ships annually ply the busy route between Dubai and Colombo. We are expecting to grab sizeable repair and maintenance work from these shipping lines. We are also expecting to offer our services to India, US and NATO Navy that operate in the Arabian Sea, Indian Ocean and China Bay regions,” Gandhi was quoted further.





Drydocking is a very complex task. First of all, the massive weight of a ship must be spread evenly to the dock. When a ship is floating, the pressure holding the ship afloat is spread throughout the entire underwater hull. In dry dock, on the other hand, the load is spread among wood blocks. There are also interferences such as transducers and irregularities such as flare at the bow. The dock master must be aware of the characteristics of the ship’s bottom and its weight distribution.
Cochin Shipyard has an order book for 20 ships at a cost of Rs 5,000 crore. Indian Navy’s order for an air defence ship, India’s first indigenous aircraft carrier, accounts for half of this amount. Last year, the shipyard did not win a single new shipbuilding order as the global economic recession took a toll on demand for new ships.
“We are talking to potential partners in the defence sector to jointly build the new dry dock,” M Jitendran, chairman and managing director of Cochin Shipyard, said recently. “We will use the dry dock for six months of the year and the partner will use it for the remaining six months,” he said.
The order book includes two anchor-handling, towing and supply vessels and two platform supply vessels ordered by Shipping Corporation of India Ltd, India’s largest ship line, worth Rs 600 crore. These orders came on the back of efforts by the Union government that owns both Cochin Shipyard and Shipping Corporation of India. The SCI contract has an option for building two more such vessels.
Pipavav Shipyard already has a dry dock that has been converted from a wet dock and measures about 662m in length and 65m in width. It is capable of accommodating ships of up to 5,00,000 dead weight tonne (DWT) and multiple combinations of smaller vessels, including vessels catering to offshore activities such as offshore supply vessels (OSV), anchor handling tug supply vessels and multi-purpose support vessels.