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Glite Dictionary
screw log

screw log

9.9
A long round object with rotating fins that measures how fast a ship moves in water
  • noun
  • Archaic
translation icon : log de tornillo
  • The crew lowered the screw log into the water to check their speed.

Examples

  • The captain checked the screw log for speed readings.

  • Before GPS, ships relied on instruments like the screw log for navigation.

  • The old sailing vessel still had a screw log stowed among its navigation tools.

  • Many ships used a screw log to measure their speed.

  • Before GPS, ships relied on instruments like the screw log to determine their speed in the water.

  • The crew lowered the screw log into the water and observed its rotation to check their speed.

  • On the old sailing ship, the screw log was an essential tool for calculating how fast the vessel was moving.

Synonyms

log
vsscrew log
  • Archaic
24 9.7

A floating object on a knotted line used from a ship to measure speed

uses a cigar shape with rotary fins rather than a float and line
patent log
vsscrew log
  • Archaic
9.9

A cigar-shaped tool with spinning fins that measures a ship's speed through the water

is identical in function but described as formerly used at sea
taffrail log
vsscrew log
  • Archaic
9.9

A device towed behind a ship that measures how fast it moves through the water

is similar but described without the stern towing detail
velocimeter
vsscrew log
  • Specialized
9.1

A tool that measures how fast something moves

is specific to ships and uses a cigar form fitted with rotary fins

Surface Forms

screw log singular
screw logs plural

Morphology

screw + log

The noun is compositionally built from 'screw' (a rotating propeller) + 'log' (a maritime speed-measuring device), so a learner who knows both senses could infer it is a type of log that uses a screw mechanism to gauge speed. However, the exact form and technical details (cigar-shaped with rotary fins) are specialised nautical knowledge and not fully predictable from the parts for an average B1 learner, making the expression only partially transparent.

Etymology

Screw log names a small floating device with a turning screw like a tiny propeller and a wooden log, which sailors dropped into the water and watched turn; the faster the screw turned, the faster the ship was moving, so the name came to mean a tool for checking a ship's 'speed'.