What is a dry dock and how does it work?

What is a dry dock is a question worth answering. These structures allow the manufacture of all types of vessels. Once completed, they are simply and quickly launched into the sea. But how does it work exactly? We discuss it below.


How does a dry dock work?

The dry dock and its meaning is as follows. It is a structure intended for the construction, maintenance and repair of vessels. It is constructed in such a way that it can be filled with water or emptied as required. Most shipyards have one or more and of various sizes to carry out production or other activities.

Larger docks allow for the manufacture and repair of massive vessels, such as container ships or ocean-going cruise ships. While in the facility, the installation is kept free of water to facilitate the work of the operators.

In terms of how a dry dock works, the structure has a bottom or dike plan, side walls, front wall and floodgate. The filling process is carried out by pumps, which fill the interior with water by gravity and up to the level of the exterior area. In this way, any ship or material can be introduced without any problems.

How a dry dock operates for ship construction and maintenance
The dry dock is a structure for the construction, maintenance and repair of vessels. Most shipyards have one or more dry docks to carry out different activities. Photo by Freepik.

Once the ship is inside, the emptying process begins, during which the water is pumped out. While this is going on, the vessel is placed on the riding surface (bottom, keel or side) to secure it once the dock is dry. Once this is completed, work on the vessel can begin.

Dry-docking is also possible. This is a complex and risky operation. It is necessary to know the dry-docking plan of the ship, data on bow and stern draft, displacement, stability conditions and load distribution. This information is essential for optimal positioning of the dry docks.

After any necessary work on the ship or on completion of its construction, the dry dock is refilled until the vessel is afloat and the water level is equal to the outside water level. The floodgate is then opened and the vessel is towed out.


Types of dry dock

There are several types of dock or dry dock to consider. Each is adapted to specific needs. For example, in a dry dock intended for small vessels a sincrolift uses articulated beams to lift the vessel. In this way, all kinds of activities can be carried out safely.

Offshore floating dock

The floating dock has floodable buoyancy chambers and a U-shaped cross-section. Its walls contribute to the stability of the platform it contains when it remains under water. The platform is submerged in these circumstances to allow the ship to enter. Once the liquid is drained, the dock rises and lifts the vessel to facilitate access to the hull.

This type is often used in the open ocean in case of emergency repairs. There are boats designed for these activities, providing a very useful tool. It can be adapted to a wide variety of situations.

Dry dock

It consists of a lock in which a ship can be placed. When it is inside the lock, the water is pumped out so that the ship rests on one or more dock blocks. These have to copy the shape of the hull to keep it stable. This is the most common type, since it is found in most shipyards. It has the appearance of a rectangular narrow basin made of reinforced concrete slab.

Dry dock is generally used for repairs. This involves cleaning the hull, removing rust and repainting. It is a routine maintenance task that prevents degradation of this part.

When positioning the ship, it may be necessary to have divers to adjust the dock blocks to the ship. This process is carried out in water, however little, so that the ship can manoeuvre. This ensures that the hull is positioned to the points where it will rest. This avoids damage to the hull due to incorrect weight distribution.


The slipway system is the most primitive type, although it is still used today. It is intended for small vessels and its structure is simple. It consists of an inclined surface on which to move the ship. The ship is lifted by trolleys  and is then pulled ashore. In this way, it is possible to carry out any repair or maintenance activity in the hull and inside. Sometimes the structure is as simple as a wooden or asphalt ramp.


It is a modern alternative to the other types. It acts as a dry dock and launching point for ships. It consists of a platform that can be raised and lowered vertically. To raise the structure, a series of hoists are used that allow synchronous lifting. Its operation is simple:

  • The platform is sunk and the ship is placed on top of it.
  • The vessel is secured by various support elements.
  • Raising the platform to the height of the quay.


Different types of dry docks for ship construction, maintenance, and repair
The main use of the dry dock is related to case cleaning, rust removal and repainting (routine maintenance). Photo by Freepik.

There are two types of platforms: rigid and articulated. The structure of the former consists of a series of beams bolted or welded together. In the latter, the main and longitudinal beams are joined together with hinged connections. In both cases, however, electric motors are used for lifting and lowering.

In short, you now know what a dry dock is. It is an essential structure for the maintenance and repair of ships. With various types available, it is possible to carry out these tasks in conditions adapted to specific boats. This ensures that the work is carried out in a satisfactory and comfortable manner. In addition, it is essential that you have a reliable partner for painting and priming activities. You can count on SuiscaGroup.