Cygnus Underwater

Diver-Held Underwater Thickness Gauge

(0 customer reviews)

The Cygnus Underwater is the original diver held subsea multiple echo Ultrasonic Thickness Gauge. It was designed for use by divers undertaking subsea maintenance and surveys 3 decades ago… and today it is still the industry standard.

The unit is depth rated to 300 meters and it provides an accurate metal thickness measurement through coatings up to 20 mm thick. The bright LED display ensures easy viewing even in poor visibility conditions.

The Underwater Thickness Gauge is supplied ready to use as a complete kit with 2 rechargeable batteries in a protective carry case.

Cygnus Instruments builds all of its equipment in the UK using only genuine and original parts and components – including Lemo® Connectors and Peli® Cases.

Select Kit

Add On Options

Additional Probes

Upgrade Kits

Umbilical Cable (+£4.00/m)


1 metre per unit- required for Upgrade Kit 'A' (TSR) with Cygnus Underwater, Upgrade Kit 'B' (CygLink) with Cygnus Underwater




  • RINA approved (Certificate No. 2009DGPO787)
  • Auto – Probe Recognition (APR)
  • “Deep-Coat” mode for measuring through coatings up to 20 mm thick (upon request)
  • Easy calibration using convenient buttons
  • Rugged, durable, shock-proof construction
  • Stable calibration – linear accuracy – no zero adjustment
  • Large bright LED display for poor visibility
  • Pressure rated to 300 m depth
  • Heavy duty sealed unit with double ‘O’ ring protection
  • Self verification of measurements to ensure accuracy
  • Echo strength indicator to aid measurement
  • All probes are protected by a membrane to prevent damage
  • Various probe options
  • Two rechargeable battery packs with charger
  • Fixed head probe option for single handed use.
Materials Sound velocities between 2000  to 7000 m/s – covers virtually all common engineering materials
Measurement Range in Steel 3 – 250 mm with 2.25 MHz probe
2 – 150 mm with 3.5 MHz probe
1 – 50 mm with 5.0 MHz probe
Accuracy 0.1 mm when calibrated in accordance with Cygnus Instruments calibration procedures
Resolution 0.1 or 0.05 mm (selectable)
Power NiMH rechargeable battery pack
Battery Life 30 hours (continuously measuring)
Display Large, bright LED display
Size 235 x 75 mm
Weight 950 g – with probe
860 g – with fixed head probe
Operating Temp -10°C to +50°C
Environmental Protection IPX8 continuous 300 m rating
Standards Designed for EN 15317
Environmental RoHS, WEEE compliant
  • Cygnus UNDERWATER Gauge Body
  • Lanyard & Molykote & Tommy Bar
  • Two Rechargeable NiMH Battery Packs
  • Battery Charger and Leads
  • Probe for Cygnus UNDERWATER, supplied as nosecone assembly with 1 m cable
  • Membrane Couplant
  • Accessories: Spare O-Rings; Spare Membranes; Membrane Locking Ring Key; 15 mm Test block; Torque (“Tommy”) bar; Calibration Jumper Lead.
Single Crystal Soft-Faced Compression 6 mm – 5 MHz
13 mm – 2.25, 3.5 or 5 MHz
19 mm – 2.25 MHz



  1. D.Miller

    I received the Cygnus 1 in 1987 and used it continuously for 10 years on submerged pipelines, without any problems. After that period it was mainly used for ship board survey inspections of hull thickness testing which is still in use today with the same set of batteries. I cannot praise this piece of equipment enough as it has given unbeatable service in extremely hostile environments without failing at any time. I would recommend this unit to anyone looking for a reliable ultrasonic thickness testing unit.

  2. Anders P.

    Since my purchase of the Cygnus 1 Underwater gauge in 2005, I have had no problem with the gauge, and it’s still going strong after 14 years of use by divers, completing many underwater inspections across countries in Africa and Europe. There were times where it wasn’t easy to get readings on odd surfaces or through small marine growth, but we succeeded eventually.

  3. Santosh G.

    There are many in the industry who have been using Cygnus meters for more than 20 years. I myself have used their underwater thickness gauge along with regular and Intrinsically Safe UT meters from the early stages of my career – and that goes back to more than 25 years for sure. TechCorr, a global leader of inspection services, uses Cygnus Gauges for pipelines, tanks and vessel inspections. Our operators particularly love Cygnus – as readings come quick and accurate.

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The Topside Repeater is used when the readings need to be verified on the surface. Umbilical cable length is specified by the customer up to a maximum of 1,000 m. There are three options available:

Option A:  Palm held surface display repeater with large liquid crystal display in an IP65 sealed case.

Option B:  Data logging and remote display Windows based *Cyglink Software. (*For more details, visit the CygLink Software page in PRODUCTS > THICKNESS GAUGING ACCESSORIES section).

Also available, the Cygnus DIVE wrist-mountable underwater thickness gauge as an alternative for diver use. For more information, visit Cygnus DIVE page and watch the Cygnus Instruments underwater ultrasonic thickness gauge video.