A dry dock (sometimes drydock or dry-dock) is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform. Dry docks are used for the construction, maintenance, and repair of ships, boats, and other watercraft.

A floating dock is a place to moor a boat on a pontoon that floats on water. The use of pontoons is to anticipate sea tides, so that the position of the ship with the pier is always the same, then between the pontoon and the pier are connected by a flexible platform/bridge to land that can accommodate the tides. this detailed floatingdock design with flexible extension:

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