stock

In shipbuilding, stock is the substantial timber or steel framework that supports a vessel's hull during construction and launch. It consists of a keel block (the main backbone running the length of the ship) and side shores or blocks that keep the hull aligned and stable as it grows. The stock must bear the entire weight of the vessel as it is built, often thousands of tonnes, and remains in place until the ship is ready to be launched or moved to a fitting-out berth.

The design of stock varies by shipyard and vessel type. A large cargo ship might rest on a keel block 200 metres or longer, supported by timber or reinforced concrete blocks spaced at intervals. Smaller craft use lighter arrangements. The blocks are set on a launching bed or building berth, which itself must be engineered to handle the load and provide a level, stable platform. For ships destined to be launched sideways, the stock is positioned perpendicular to the water; for end-launch, it runs parallel.

Launching and Movement

Once construction is complete, the ship is freed from stock. In a traditional launch, greased ways allow the vessel to slide off the stock into the water. In modern shipyards, the entire stock assembly may be rolled or skidded aside, or the ship is moved by crane or floating dock. Poor design or maintenance of stock has caused launching accidents when blocks failed under load or hull sections rested unevenly, creating excessive stress points.

The term stock comes from its primary function: it is the standing timber or frame on which work is stocked or laid. This usage appears in other trades as well, such as a gunsmith's stock or a woodworker's bench stock. In historical wooden shipbuilding, the stock was always timber; modern yards use reinforced concrete or welded steel for larger vessels because they offer better load distribution and require less maintenance than wood.

Stock is distinct from scaffolding, which is temporary support for workers and materials. The stock itself is load-bearing infrastructure that defines the structural integrity of the build. Its placement and condition directly affect the quality of the launch and the longitudinal stresses the hull endures during construction. Shipyard records identify each stock position by its location on the berth, and blocks are numbered for reuse or replacement.