G-882 Marine Magnetometer

The model G-882 cesium-vapor marine magnetometer provides the same high performance as our airborne instruments delivering high resolution results in all types of survey applications. The G-882 is a low cost, compact system designed for professional surveys in shallow or deep water.

The G-882 magnetometer’s digital output can be recorded with any serial data logger but its full potential is obtained when used with our MagLog Lite™ software to log, display and print GPS positioned measurement results. The price, performance and reliability of the G–882 make it the best value of any marine magnetometer available today.

Geometrics G-882 marine Magnetometer

The G-882 is designed for operation from small vessels for shallow water surveys as well as for large survey vessels for deep tow applications (4,000 psi rating, telemetry over steel coax available to 10Km). Being small and lightweight (40 lbs net, no extra weights) it is easily deployed and operated by one person. Power may be supplied from a 24 to 30 VDC battery power or the included 110/220 VAC power supply. The standard G-882 tow cable includes a Vectran strength member and can be built to up to 700m (no telemetry required). The shipboard end of the tow cable is attached to an included junction box or optional on-board cable for quick and simple hookup to a power source. Output data can be recorded on any Windows 98, ME, NT, 2000 or XP computer equipped with RS-232 serial ports. Best of all, the rugged G-882 is designed for and has been used successfully everywhere in the world for all types of applications.

The G-882 Marine Mag in Malta, courtesy of Garry Kozak

The G-882 Cesium magnetometer provides the same operating sensitivity and sample rates as the larger deep tow model G-880. MagLogLite™ Logging Software is offered with each magnetometer and allows recording and display of data and position with Automatic Anomaly Detection! Additional options include: MagMap plotting and contouring software and post-acquisition processing software MagPick™ (free from our website.)

Shown is a unique application for multiple mag G-882 array for UXO detection. Photos courtesy of Sky Research.

The G-882 system is particularly well suited for the detection and mapping of all sizes of ferrous objects. This includes anchors, chains, cables, pipelines, ballast stone and other scattered shipwreck debris, munitions of all sizes (UXO), aircraft, engines and any other object with magnetic expression. Objects as small as a 5 inch screwdriver are readily detected provided that the sensor is close to the seafloor and within practical detection range.


Calculate the depth of your fish, given boat speed, cable and instrument type and length of cable. Click Here (must have Java enabled)

NOTE: Due to changes in the latest Java updates (starting with Java 7 update 51), you will need to adjust your security settings and add Geometrics' Support site to your exceptions list as follows:

  1. Go to your computer's Control Panel
  2. Choose Programs
  3. Click on the Java Icon
  4. Choose the Security tab
  5. In the Exception Site List section, click "Edit Site List..." and enter:
    in the box provided and click Apply and then OK:

Pearl Harbor

Watch Ross Johnson, VP of Magnetometer Division, review the mag survey recently completed at Pearl Harbor using our G-882 TVG.

The following YouTube clip has some footage of the G-882 and a good introductory treatment of marine surveying for shipwrecks.

Typical Detection Range For Common Objects

Ship 1000 tons: 0.5 to 1 nT at 800 ft (244 m)
Anchor 20 tons: 0.8 to 1.25 nT at 400 ft (120 m)
Automobile: 1 to 2 nT at 100 ft (30 m)
Light Aircraft: 0.5 to 2 nT at 40 ft (12 m)
Pipeline (12 inch): 1 to 2 nT at 200 ft (60 m)
Pipeline (6 inch): 1 to 2 nT at 100 ft (30 m )
100 kg of iron: 1 to 2 nT at 50 ft (15 m)
100 lbs of iron: 0.5 to 1 nT at 30 ft (9 m)
10 lbs of iron: 0.5 to 1 nT at 20 ft (6 m)
1 lb of iron: 0.5 to 1 nT at 10 ft (3 m)
Screwdriver 5 inch: 0.5 to 2 nT at 12 ft (4 m)
1000 lb bomb: 1 to 5 nT at 100 ft (30 m)
500 lb bomb: 0.5 to 5 nT at 50 ft (16 m )
Grenade: 0.5 to 2 nT at 10 ft (3 m )
20 mm shell: 0.5 to 2 nT at 5 ft (1.8 m)

The design of this high sensitivity G-882 marine unit is directed toward the largest number of user needs. It is intended to meet all marine requirements such as shalllow survey, deep tow through long cables, integration with Side Scan Sonar systems and monitoring of fish depth and altitude.

Garry Kozak

Photo courtesy of Garry Kozak

  • Fastest sampling at high sensitivity means even small targets can be detected
  • Cesium vapor technology provides furthest detection range. highest sensitivity at 0.004 nT/sqrt(Hz)
  • New streamlined design improves safety, less chance of snagging on rocks or debris
  • Convertable nose or CG tow mechanism, lets you choose survey style, gets fish deeper.
  • Flash memory stores all parameters, eliminates need for on-board reprogramming
  • Optional sonar altimeter provides integrated measurement of tow fish’s height above seabed when closer than 100 meters.
  • A 2700m (9000') depth rating lets you use one mag for all surveys
  • Easy portability and handling - no winch required- single man operation, 44 lbs with 200 ft cable (without weights or depressor wing), new carrying handle
  • Combine as many as 6 systems for increased coverage – the internal CM-221 Mini-Counter allows multi-sensor data concatenation. Multi-sensor systems allow dense coverage that maximizes detection of small targets.
  • Two Year Warranty


  • Operating Principle: Self-oscillating split-beam Cesium Vapor (non-radioactive)
  • Operating Range: 20,000 to 100,000 nT
  • Operating Zones: The earth's field vector should be at an angle greater than 6o from the sensor's equator and greater than 6o away from the sensor's long axis. Automatic hemisphere switching.
  • CM-221 Counter Sensitivity: <0.004 nT/ pHz rms. Typically 0.02 nT P-P at a 0.1 second sample rate or 0.002 nT at 1 second sample rate. Up to 40 samples per second
  • Heading Error: <1 nT over entire 360o spin and tumble
  • Absolute Accuracy: <3 nT throughout range
  • Output: RS-232 at 1,200 to 19,200 Baud


  • Sensor Fish: Body 2.75 in. (7 cm) diameter, 4.5 ft (1.37 m) long with fin assembly (11 in. cross width), 40 lbs. (18 kg) Includes Sensor and Electronics and 1 main weight. Additional collar weights are 14lbs (6.4kg) each, total of 5 capable
  • Tow Cable: Kevlar Reinforced multiconductor tow cable. Breaking strength 3,600 lbs, 0.48 in OD, 200 ft maximum. Weighs 17 lbs (7.7 kg) with terminations.
  • Operating Temperature: -30oF to +122oF (-35oC to +50oC)
  • Storage Temperature: -48oF to +158oF (-45oC to +70oC)
  • Altitude: Up to 30,000 ft (9,000 m)
  • Water Tight: O-Ring sealed for up to 9000 ft (2750 m) depth operation
  • Power: 24 to 32 VDC, 1.0 amp at turn-on and 0.5 amp thereafter

    Standard Accessories:
    View201 Utility Software, operation manual and ship kit

    Telemetry to 10Km coax, gradiometer (longitudinal or transverse), reusable shipping case

    MagLog Lite™ Software:
    Logs, displays and prints Mag and GPS data at 10 Hz sample rate. Automatic anomaly detection and single sheet Windows printer support

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