Dry Docking Process

Current Dry Docking Capability

Today there are dry docks of various types up and down the British Columbia coast. These facilities have a multitude of customers: commercial freighters, cruise ships, barges, warships, large and small tugs, ocean-going platforms, drill rigs, cable laying vessels, research ships, yachts, and fish boats.

Dry docks serve not only their customers, but also their respective communities by providing meaningful work and spinoff industries.

The largest dry dock in BC, the Esquimalt Graving Dock, is located in Victoria and is managed by Public Works and Government Services Canada (PWGSC). It has the distinction of being the largest hard-bottomed drydock on the west coast of the Americas.

The following video shows The BC Ferry Spirit of Vancouver being dry docked at the Esquimalt Graving Dock.

How Dry Docking Works

The in-ground dock is essentially a large trench or excavation that is below the level of the surrounding water. The entire structure is lined with cement or large stone blocks to support heavy work activities that are going on while the ship is in dock.

The area to construct the dock is chosen for its strategic location such as a cove or sheltered area to provide protection from winds and high water. Some in-ground docks are located over very hard bedrock to minimize construction costs and to provide the ultimate in stability for large vessels, while others are in close proximity to supplies or railway lines.

When a ship is to be taken out of the water for scheduled maintenance, the dock is pumped down until it is dry. Pressure from surrounding water will keep the snug fitting gate or 'caisson' in place, thus ensuring the watertight integrity of the dock.

Large blocks are then strategically placed on the centerline of the dock bottom to align with the keel of the ship. Water is then allowed to flood into the dock through large inlet valves in the caisson. When the water level inside and outside the dock has been equalized, the buoyant caisson is removed/opened and the ship can be sailed, pulled, or tugged into the dock and positioned exactly over the pre-set blocks. The caisson is then closed, the water is slowly pumped out again and as the ship settles onto the blocks, additional supports are placed between it and the side of the drydock to stabilize it and keep it upright.