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Docks: Docks are enclosed areas for berthing the ships to keep them afloat at a uniform level to facilitate loading and unloading cargo.

CLASSIFICATION OF DOCKS: Docks can be classified into following two categories:Wet docks. Dry docks.

WET DOCKS: Docks required for berthing of ships or vessels to facilitate the loading and unloading of passengers and cargo are called wet docks. These are also known as harbor docks.

CONSTRUCTION OF WET DOCKSWet docks are large areas of water bounded by vertical solid walls against which vessels tie up. The walls must be impermeable to retain the water at high tide level. Locks are provided if entry to the dock is desired at times other than high tide The walls may be formed by sinking monoliths to a suitable depth and joining them together with insitu concrete. A space of 2 to 3 meters is left between the monoliths to facilitate jointing and finishing. Alternatively, the walls may be constructed with deep diaphragms, decking being supported by cross-wall diaphragm.

DRY DOCKS: The docks used for repairs of ships are known as dry docks.

CLASSIFICATION OF DRY DOCKS: Dry docks are classified in the following three categories: Graving dry docks. Floating dry dock. Marine railway dock.

GRAVING DRY DOCK: It is long excavated chamber, having side walls, a semi circular end wall and a floor. The open end of the chamber is provided with a gate and acts as the entrance to the dock.

CONSTRUCTION OF GRAVING DOCKSheet piles are installed.The site sand is partly excavated and the water is removed.The concrete floor is laid after excavation. The side walls are formed with a series of steps to receive the end of shores which support the ship in a vertical position.On the floor keel blocks are fixed on which the ship is brought to rest when the water from dock is removed.A gate is provided at the opening of dock for entrance and with drawl of ship.

GRAVING DOCK CONSTRUCTION DIAGRAM

FLOATING DRY DOCK: It may be defined as a floating vessel, which can lift ship out of water and retain it above water by means of its own buoyancy. It is a hollow structure made of steel or R.C.C consisting of two walls and a floor with the ends open. It is often used to rescue damaged ships in sea.

CONSTRUCTION OF FLOATING DOCKSIt is a hollow structure of steel, or concrete consisting of two side walls and a floor, with the ends open. To receive a ship, the structure is sunk to required depth by ballasting its interior chambers with water, the ship is then floated into position and berthed.

MARINE RAILWAY DOCK: The marine railway or slip dock is an inclined railway extending from the shore well into the water. This railway track is used to draw out a ship needing repair out of the water.

CONSTRUCTION OF MARINE RAILWAY DOCKA set of piles is provided.longitudinal timbers(used as sleepers) are set on beams which are resting on piles.A steel cradle is constructed which moves on an inclined track provided with kneel block.

MARINE RAILWAY DOCK CONSTRUCTION DIAGRAM