A type of screw, not perfected until the 1870s, which is used to adjust any rigging equipment for length or tension, the correct maritime term being to ‘set up’ the rigging. It consists of an internally threaded sleeve into which a right-handed screw takes at one end and a left-handed screw at the other. As the sleeve is revolved, the two contra-threaded screws are drawn together, thus increasing the tension of those parts of the rigging to which they are attached. Bottlescrews are largely used for setting up the shrouds of sailing vessels and the guardrails and davit guys fitted in ships. A large bottlescrew is also used in a cable stopper called a screw slip. This secures an anchor in a hawsepipe by screwing it home until the anchor flukes are hard up against the rim of the hawsepipe so that it cannot move when the ship pitches in heavy seas.
Subjects: Maritime History.