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TOEIC Link Vocabulary Cluster — Echo Sounder and Speed Log Survey: The Report Lexicon for the Instruments That Tell a Ship Its Depth and Its Speed

An echo sounder and speed log survey checks the two instruments that tell a bridge how deep the water is and how fast the ship is moving — the transducer, the display, the through-hull fitting, and the log that feeds speed to the radar and the recorder. This cluster isolates the 40-plus terms the survey deploys and maps each to its register tier and native collocation, so a TOEIC Link marine survey reading passage becomes a domain you read at speed rather than decode word by word.

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TOEIC Link Vocabulary Cluster — Echo Sounder and Speed Log Survey: The Report Lexicon for the Instruments That Tell a Ship Its Depth and Its Speed

A bridge that cannot see the water under the keel and cannot read the ship's speed through it is a bridge navigating blind. Two instruments remove that blindness: the echo sounder, which measures the depth of water below the hull by timing a sound pulse to the seabed and back, and the speed log, which measures the ship's speed through the water — and on modern installations its speed over the ground as well. A survey of these instruments is not a check that they switch on; it is a check that the numbers they display can be trusted, because a depth reading that lies by two metres in shoaling water and a log that over-reads by a knot both feed decisions that put the ship aground. That workflow recurs as a source domain for TOEIC Link marine survey reading passages, and it generates a cluster of roughly forty terms. A candidate who owns the cluster reads the passage at native speed; a candidate who does not stalls on the sensor nouns and loses the accuracy argument the passage is built on.

This guide isolates the cluster, groups it by survey stage, and maps each term to its native collocation and register tier, because TOEIC Link scores writing as well as reading. Pair it with the gyro compass and navigation repeater cluster, whose heading-sensor vocabulary runs alongside this one on the same bridge, and with the GMDSS radio installation and EPIRB cluster, whose survey-and-certification workflow parallels the periodic testing this instrument survey applies.

Why this cluster rewards study

A navigation-instrument passage assumes its vocabulary the way a boiler or compressor passage does. If a reader decodes transducer, through-hull fitting, and speed over ground one word at a time, the attention the module intends for the inferential questions is consumed by decoding. Learning the cluster converts those stalls to zero and frees the reader to answer what the passage actually asks — why a sounder that displayed a depth was still condemned, what a log that read cleanly alongside was really failing to prove at sea, and where in the accuracy argument the disputed finding lies.

Stage 1 — The echo sounder: transducer, pulse, and the seabed return

Survey begins under the keel. The echo sounder sends a pulse from a transducer mounted in the hull, and the surveyor confirms the transducer's through-hull fitting is sound and the sensor face is free of the fouling and air bubbles that scatter the pulse. The instrument times the echo returning from the seabed and converts it to a depth reading shown on the display unit, and the surveyor checks the reading against a known depth — usually the draught alongside — to confirm the calibration. A passage most loves a sounder whose transducer had silted over so the return was weak and the displayed depth crept shallow. A candidate who can read the sensor chain at a glance keeps the geography of the passage straight.

  • echo sounder / depth sounder — measures water under the keel; collocates with depth below keel, shoal warning
  • transducer — sends and receives the pulse; collocates with hull-mounted, transducer face
  • through-hull fitting — the penetration housing the sensor; collocates with sea valve, watertight
  • echo / seabed return — the reflected pulse; collocates with weak return, false echo

Stage 2 — The speed log: through the water and over the ground

Next the survey turns to speed. The speed log measures the ship's motion, and the surveyor first identifies which quantity it reports: speed through the water, which a electromagnetic log or a Doppler log derives from the flow past a sensor, or speed over the ground, which a dual-axis Doppler log or a GPS feed derives from the seabed or satellites. The surveyor checks the sensor fitting — often a retractable log tube through the hull — and confirms the log's distance run counter accumulates correctly. A passage most loves a log that read true through the water but was mistaken for ground speed in a current, so the ship made good far less than the bridge believed. This is the mechanical spine of a log passage.

  • speed log / speed indicator — measures the ship's speed; collocates with log reading, speed input
  • speed through the water (STW) — motion relative to the sea; collocates with current effect, flow sensor
  • speed over the ground (SOG) — motion relative to the seabed; collocates with Doppler lock, bottom track
  • distance run — accumulated distance; collocates with log counter, nautical miles

Stage 3 — The feeds: what the instruments drive

Here the survey reaches its consequence. The echo sounder and the log do not stand alone; their outputs feed the radar, the ARPA plot, the ECDIS chart, the autopilot, and above all the voyage data recorder, and the surveyor confirms each data feed is present and reads correctly at the receiving instrument. The log's speed feeds the radar's true-motion picture and the collision-avoidance vectors, so a log that over-reads corrupts every derived vector on the bridge. A passage most loves a wrong speed feed that propagated silently into the radar plot and put a false closest-point-of-approach in front of the officer of the watch. A candidate who owns this vocabulary reads the middle of the passage — usually where the propagated error is introduced — without stalling.

  • data feed / input — the signal to other instruments; collocates with serial output, NMEA sentence
  • radar / ARPA input — uses the speed for true motion; collocates with true-motion display, vector
  • autopilot input — uses speed and heading to steer; collocates with course keeping, rudder order
  • voyage data recorder feed — logs depth and speed; collocates with recorded parameter, data channel

Stage 4 — Proving the paper: testing, records, and the verdict

The survey closes on testing and paper. The surveyor confirms the instruments were subject to the required performance test and annual survey, checks the maker's manual setting against the installed calibration, and reads the survey report against the navigation equipment certificate and the last test record. The report and the certificate are only credited when the displayed numbers, the feeds, and the records agree. A candidate who owns the paper vocabulary reads the closing paragraph — almost always the one carrying the verdict — without stalling.

  • performance test — proves the reading is accurate; collocates with annual test, witnessed test
  • calibration record — the accepted correction; collocates with calibration certificate, correction table
  • navigation equipment certificate — the credited paper; collocates with endorsement, survey cycle
  • survey report / verdict — the closing judgment; collocates with defect noted, condition of class

How to drill this cluster for a live passage

Read the four stages as a chain: pulse to the seabed → speed through the water → feeds to the bridge → the paper that credits them. A TOEIC Link passage on navigation instruments almost always follows that chain, and the disputed finding usually sits at the seam between two stages — a transducer return that was weak (Stage 1) but whose depth was trusted, or a log that read true (Stage 2) but fed the radar a wrong speed (Stage 3). Learn the seams and you predict where the question lives.

For output practice, write one sentence per stage using a native collocation from the list, then compress the four sentences into a 60-word survey note. That is the exact register TOEIC Link writing rewards, and it is the register a real navigation-equipment survey report is written in.

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