Ultrasonic Digital Thickness Gauge for Underwater Use, Model 1 by Cygnus

Hand-held, Underwater Metal Wall Ultrasonic Digital Thickness Gauge. Measures metal thickness to 1,000 feet under water to determine wastage or corrosion -- accurately, quickly and without removing surface coatings.

  • Diver held underwater thickness gaugel
  • Pressure rated to depth of 1000 ft (300 m).
  • Heavy-duty sealed unit with double "O" ring protection.
  • Remote probe with 3 ft (0.9 m) lead for measuring in awkward locations.
  • Rugged durable shock proof construction.
  • Stable calibration - linear accuracy - no zero adjustment.
  • Various probe options.
  • Two rechargeable batteries with charger.
  • Large, bright LED display for poor visibility.
  • All probes protected by a membrane to prevent damage.
  • Self-verification of the measurements to ensure accuracy.
  • Echo strength indicator to aid measurement.
  • Easy calibration using convenient buttons - NEW feature
  • Deep-Coat mode measuring through coatings up to 20mm thick - NEW feature
  • Auto-Probe Recognition (APR) - NEW feature
Kit Contents
  • Instrument.
  • Heavy duty, remote 2.25 MHz, 13 mm diameter probe.
  • Nose cone tommy bar.
  • Probe locking key ring.
  • Two rechargeable batteries and battery charger.
  • Spare membranes and "O" rings.
  • Steel test block.
  • Lanyard.
  • Molykote grease.
  • Carrying case.
  • Operating manual.
  • Pressure test and calibration certificates.


  • Metal thickness and corrosion checks on offshore structures and ships.
  • Safety corrosion monitoring of pipelines and storage vessels.
  • Metal thickness / wear checks on anchor chains, jetties, dock gates, piers and pilings.
  • Ships classification surveys.
  • Maintenance and safety checks on bridges.
  • Coatings do not have to be removed - measures only the metal thickness.
  • Accepted by major classification societies.
  • No grinding - minimum surface prep.
  • Measures on rough corroded surfaces.
  • Speed, accuracy and reliability.
  • No false readings - repeatable results.
  • Easy to use - minimum operator training.
  • Greatly reduced inspection time & cost.
  • Measures on metals and some other materials.


Cygnus Multiple Echo Technology

With multiple echo technology, readings are taken by measuring the time delay between any three consecutive backwall echoes. The time T1 (for coating thickness) is ignored. The times T2 and T3 are equal to the time that it takes for sound to travel through the metal. Only by looking at three echoes can the measurements be made for the metal thickness, where T2 = T3.



Sound velocities between 2000 m/s and 7000 m/s.


3 mm - 250 mm with 2.25 MHz probe.
2 mm - 150 mm with 3.5 MHz probe.
1 mm - 50 mm with 5 MHz probe.


±0.1 mm or ±0.05 mm


0.1 mm or 0.05 mm


Remote single-crystal, soft-faced compression.
6 mm - 5 MHz
13 mm - 2.25 MHz, 3.5 MHz or 5 MHz
19 mm - 2.25 MHz


Two NiMH rechargeable batteries


Large, clear LED display with polarized filter.


238 x 85 mm


977 g with remote probe.

Operating Temperature

-10ºC to +50ºC


3 years

Topside Repeater Options

The topside repeater is available in case of poor visibility or when the readings need to be verified on the surface. Umbilical cable length is specified by the customer up to a maximum of 1000 m. Three options are available:

  • Option APalm-held surface display repeater with large liquid crystal display in an IP65 sealed case.

  • Option B
    Windows based software for datalogging and remote display. The umbilical is connected to the serial port of a PC (PC not included). 

  • Option C = Options A + B 
    All Cygnus Underwater gauges with Topside Repeater Connectors can be upgraded to Option A, B or C.