Maintenance of the ships and boats irrespective of their size at regular intervals is of utmost importance for reasons of safety and prolonging the life of the vessel. The maintenance activity is not only limited to the interiors and the machinery on the ship but also carried out on the outer portions of the ship. One of the techniques that is adopting for carrying out repairs is termed as dry dock. Let us try and understand what is a dock before proceeding to understand a dry dock and its types.

What is a dock?

A dock is an area of water that exists between two piers or alongside a pier. It is a platform that is built from the shore into the water. It is supported on piles. The dock area is used for various purposes from recreation, fishing commercial activities and even while carrying out repairs of sailing vessels. The base of the dock can be constructed using aluminum or even wood. A dock may be an isolated structure or may be combined with more structures.

What is a dry dock?

Dry dock is the area where sailing vessels come for repairs. The water is drawn out of the dock and hence the term ‘dry dock’ was coined. The structure is constructed in such a manner that it allows a vessel to be sailed in and then the water is drained out. This ensures that the maximum area of the vessel is available for examination and carrying out repairs.

Types of Dry Docks:

There are different types of dry docks that are usually constructed. Some of the types of dry docks are:

• Stationery Docks
• Floating Docks
• Patent Slips
• Ship Lifts

Stationery Dry Docks:

The first type of a dry dock is stationery in nature and is in use since the ancient times. In this the structure of the dock is connected to a harbor. It is separated from the main water body by the use of gates. Digging is done in the area, and the earth removed in order to provide support to the structure. When a ship has to sail in the dock is flooded and then the water is drained with the help of pumps.

Floating Dry Dock:

This is also an ancient technique to construct a dock. A dock comprises of multiple chambers which are flooded or drained to sink or float as and when required. This is done with the ship positioned close by. These docks serve their purpose well while repairs are carried in the open ocean.

Patent Slips:

this technique is generally resorted to for smaller ships. It is like a jack up system. Cradles are made to role till they are right below the ship. Once the cradles are below the ship, they are jacked at 90⁰ bringing the ship above the surface of the water.

Ship Lifts:

This works quite like the Patent slips with the difference that, a platform is slipped under the vessel in this case. The limitation of this method is that just like patent slips it cannot be used for very large ships.

How and where a ship is dry docked is important. Care has to be taken to ensure that the ship does not list in one direction and undue pressure is not laid on the hull of the vessel.

A Side Effect

Dry docks may seem a boon for the shipping industry, but they have their inherent drawbacks. Dry docks do not have a positive effect on the environment. They tend to destroy the aquatic habitat in the region. The expanse of the wetlands and marshlands while increasing the pollution and erosion taking place in the area.

Yet this is something which the marine industry cannot survive without, hence it is upto the shipping industry and the regulatory bodies to ensure that the dry docks and environment exist harmoniously with least bad effects on the environment.

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