Ship launching is the process of transferring a vessel to the water. It is a naval tradition in many cultures, dating back thousands of years. It has been observed as a public celebration and a solemn blessing.
Ship launching imposes stresses on the ship not met during normal operation, in addition to the size and weight of the vessel, and it represents a considerable engineering challenge as well as a public spectacle. The process also involves many traditions intended to invite good luck, such as christening by breaking a sacrificial bottle of champagne over the bow as the ship is named aloud and launched.
There are three principal methods of conveying a new ship from building site to water, only two of which are called "launching." The oldest, most familiar, and most widely used is the end-on launch, in which the vessel slides down an inclined slipway, usually stern first. With the side launch, the ship enters the water broadside. The third method is float-out, used for ships that are built in basins or dry docks and then floated by admitting water into the dock. In all cases, heavy chains are attached to the ship and the drag effect is used to slow the vessel once afloat, until tugboats can move the hull to a jetty for fitting out.