Davit: From scripture to the scaffold

To most people, a davit is simply a crane or hoist, if they know the word at all. But in construction and maritime work, it is a specific piece of equipment: a pivoting or swinging crane arm, typically made of steel, used to lower personnel, equipment or lifeboats over the side of a vessel or down the face of a tall structure. Davits almost always work in pairs, one on each side, to keep loads balanced and stable as they descend.

In construction, a davit is deployed for facade maintenance, window washing and repairs to the exteriors of tall buildings. A worker in a suspended maintenance trapeze or cage is lowered by the davit, which can swing inward and outward to position the load. On ships and offshore platforms, davits serve the same function but for a different critical purpose: launching and retrieving lifeboats. A ship's davits must be robust enough to handle the weight of a fully loaded lifeboat and its occupants, and reliable enough that they work on demand in an emergency.

The davit's name is the point of mystery. The most plausible account traces it to davit, a small hoist that resembled a biblical sling or crane used by the ancient Hebrews, though this connection is speculative and no authoritative etymology has been established with certainty. What is clear is that the term entered English maritime vocabulary and was already in use by the 18th century to describe the shipboard hoist.

The davit works by a system of pulleys, wire ropes and a winch. The jib arm is mounted on a pivot; it swings up and out to extend the load away from the building or vessel, then lowers it using a mechanical brake and motor or manual winch. Modern davits are often hydraulic, with smooth descent control that prevents jerking or free-fall. Some davits are fixed in position, while others are portable and can be repositioned as needed.

Because davits are used to lower people over long drops, their design is heavily regulated by maritime and occupational safety codes. Inspection, load rating, brake testing and certification are mandatory. A failed davit in service means a catastrophic fall, so the engineering is conservative and the maintenance discipline is absolute.