Types of Dry Docks in Maritime Operations

What are dry docks of ship?

Dry docks are maritime facilities where vessels are moored for maintenance and repairs. These are also used for assembling the parts to construct a new vessel. Different types of dry docks serve various purposes. Dry docks benefit crew training as they see the complete vessel without any part submerged under the water. Graving, floating, syncolifts, and marine railways are a few dry docks commonly used in the maritime industry, where ship owners schedule their ships for repairs and maintenance. Let us learn more about the various types of dry docks in detail. 

What is a dry dock, and how does it work? 

A dry dock is a maritime structure built inside the service yard drained of water to allow workers to construct a new ship or carry out maintenance and repairs on the ship. They are located in coastal areas near water bodies, allowing ships to sail after construction, maintenance or repair. After conducting the needed work on the ship, the dry dock acts as a basin that can be filled with water to float the ship. The process of dry docking refers to the movement of a ship from water to dry land where it can rest with its hull exposed, which otherwise stays under the water. Usually, ships are taken to the dry docks once in five years but can be taken midway if the need arises or if any inspections and repairs are needed. 

A dry dock is equipped to start and stop the flow of water with anchors that can hold various lines in shipping. The dry-docking process includes- 

  • The watergates of the dry dock are opened to fill the dock with water so that the ship can easily float inside the dock. 
  • The lines in shipping are adequately secured, and the ship is moored, followed by the dewatering of the dry dock. 
  • The water gates are closed after draining water from the dry dock, and the vessel inspection begins. 
  • The deck, hull, propellers and other necessary machinery are checked, and all required maintenance and repairs are performed.  
  • In constructing a new ship, there is no need to water and dewater the dock. It’s built in a dry area. 
  • After completing the construction or maintenance of the ship, the dock is filled with water to allow the ship to float and exit effortlessly. 

What are the different types of dry docks used in maritime operations? 

Different types of dry docks are based on their use in the maritime industry. Let us learn more about the various kinds of dry docks in maritime. 

  1. Graving dry docks – Located near coastal areas, a graving dry dock is a rectangular construction previously made using stone and timber but now built using steel and concrete. The heavy steel gates help release, store, and drain water from the dry docks. Graving docks can accommodate larger sea vessels than other dry docks. Workers can efficiently conduct modifications concerning the ship here. Big-size graving docks can even accommodate two vessels at one time. 
  2. Floating dry dock – Floating docks are used for ships that are to be salvaged due to some maritime accidents and damaged beyond a point where they can no longer sail to a coastal dock. These are “U” shaped docks capable of submerging themselves a bit in water to allow the ship to move onto the dock in position. Once the ship is positioned on the dock, it is uplifted out of water and deballasted to take out all residual water. These mobile dry docks can be quickly propelled to the location of any maritime accident to conduct repairs.
  3. Syncrolift dry dock – They are also known as shiplifts as they raise and lower the ship as required. Syncrolifts dry docks are platforms attached to a series of lifting cradles. The vessel is positioned on the cradles, and the platform is seamlessly raised to perform inspections, maintenance, and repairs. 
  4. Marine railway dry dock – These are types of dry docks where a set of tracks, like railways, extends into the water. The ship is attached to a cradle or carrier that can quickly move on these tracks. It allows an easy method to push newly constructed ships into the water using the tracks. Ships that require maintenance and repairs use a geared hauling machine to pull ships out of water. 

Importance of dry docks 

Dry docks are used across the maritime industry for various reasons. Let us learn more about the purpose of dry docks.  

  • It acts as a construction site for various types of containerships where the entire ship is pieced together. 
  • Dry docks are also sites for learning where the ship’s crew learns about the ship’s structure that cannot be explored when the ship is on water. 
  • All inspections of the ship are conducted at the dry port. It helps detect any anomalies within or outside the ship and allows workers to improve it.  
  • It helps improve ships’ performance by repairing any external or internal damage, technical failures, hydraulics repairs, and replacing new parts. 
  • Dry docks also serve as maintenance sites for ports. Painting, cleaning and general upkeep of ships help improve their lifespan and enhance aesthetics. 

What factors are considered in selecting the appropriate dry dock for a vessel? 

While choosing a dry dock, it is necessary to consider the following factors. 

  1. Size of the vessel – Various types of containerships vary based on the TEU and FEU of the ships. Different dry docks have different capacities to accommodate shipping vessels. For vessels of considerable size, the ship owner must choose to grave dry docks for shipping maintenance and repairs. For smaller size vessels, syncrolifts are most suited. Marine railway dry docks are suggested for average-sized vessels of around 10000 Tonnes. 
  2. Condition of the vessel – If a ship suffers damage due to collision or other maritime accidents and cannot sail during its voyage, floating dry docks are the best choice for retrieving the salvaged ship.  
  3. Nature of repairs – If the sea vessel is scheduled for routine repairs and maintenance, choosing a floating dry dock is more appropriate. Meanwhile, in case of significant repairs involving retrofitting or replacing vessel parts, graving dry docks are suitable as equipment and machinery can be easily made available from land to dock. 
  4. Vessel schedule – The dry dock must be decided based on the shipping schedule, the nearest dry docks, and the time taken for the ship to reach the dry dock after unloading goods on the last port of call. It is also essential to analyze the urgency of repair and maintenance. 
  5. Budget – Graving docks require more investment than floating docks. Marine railways are economical and convenient for vessel owners to dock their ships. 

How has technology evolved in dry dock facilities over the years? 

Using technology in dry docks helps improve the operational efficiency of dry docking. Let us learn more about a few technologies used in dry docks. 

  1. Computer-Aided Designs – CAD allows ship manufacturers and owners to hire ship designers to create sustainable plans and designs that are easier to implement at dry docks. Construction of ships has become easier using digital designs. The ship design is optimized for various factors, such as managing the weight of ships to maintain their stability and elevating the ship’s sustainability. 
  2. Automation and robotics – Using artificial intelligence and machine learning, robotics and automation make it possible to carry out various dry-docking activities, such as painting and welding, seamlessly. Robotics can carry heavy machinery in and out of docks, increasing efficiency and decreasing the time taken. 
  3. Use of sensorsIoT in shipping allows ship owners to get real-time information about the ship’s health as it prompts any corrosion, wear, or tears in real-time. It allows ship owners to carry out timely maintenance and repairs. 
  4. Data analyticsPredictive analytics helps collect data from IoT sensors to suggest potential failures and identify trends and patterns in docking. 

    These types of dry docks allow ship owners to schedule timely maintenance and repairs of ships. 

    LOTUS Containers is a shipping container service provider in Germany that sells shipping containers in all sizes, including 53ft, 45ft, and 40ft.

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