SonTek CastAway® CTD

Designed for coastal profiling, the CastAway-CTD® incorporates a 6-electrode conductivity cell, coupled with a fast response thermistor to provide highly accurate, high resolution CTD measurements to depths of 100m.

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Field Ready and Rugged

The CastAway-CTD is a small, rugged and technically advanced CTD designed for profiling to depths of up to 100m. The system incorporates modern technical features which allow it to achieve a 5 Hz response time, fine spatial resolution and high accuracy. It uses a six electrode flow-through conductivity cell with zero external field coupled with a rapid response thermistor to attain high measurement accuracies. The instrument is simple to deploy, does not require a pump and is hydrodynamically designed to free fall rate of 1 m/s.

The integrated real-time data display screen, internal GPS sensor and automated wireless data transfer are unique features that simplify data collection.

  • Salinity Accuracy: 0.1 PSU
  • Temperature Accuracy: 0.05°C
  • Small size
  • Integrated GPS position
  • Real-time display screen
  • Wireless data transfer
  • 5 Hz sampling rate

Each CastAway-CTD cast is referenced with both time and location using its built-in GPS receiver. Latitude and longitude are acquired both before and after each profile. Plots of conductivity, temperature, salinity and sound speed versus depth can be viewed immediately on the CastAway's integrated color LCD screen in the field.  Raw data can be easily downloaded via Bluetooth to a Windows computer for detailed analysis and /or export at any time.

*US Patent #8272262

Parameter Specification Range Resolution Accuracy Method
Conductivity 0 to 100,000 µS/cm 1 µS/cm 0.25% ±5 µS/cm Measured
Density 990 to 1035 kg/m3 0.04 kg.m3 ± 0.02 kg/m3 EOS80••
Depth 0 to 100 m 0.01 m ±0.25% FS EOS80••
GPS - - 10m -
Pressure 0 to 100 dBar 0.01 dBar 0.25% of FS Measured
Salinity Up to 42 0.01 ±0.1 PSS-78
Sound Speed 1400 –1730 m/s 0.01 m/s ±0.15 m/s Chen-Millero
Specific Conductivity§ 0 to 250,000 µS/cm 1 µS/cm 0.25% ±5 µS/cm EOS80••
Temperature -5 to +45°C 0.01°C ±0.05°C Measured

Based on temperature resolution and accuracy.
••International Equation of State for sea water (EOS-80).
1978 Practical Salinity Scale
Chen-Millero, 1977. Speed-of-sound in sea water at high pressures.
§ Based on 100,000 µS/cm at -5°C.

Communications Internal BlueTooth Radio (Class 2)
Up to 10m range
Dimensions — Diameter 7.11 cm | 2.8 in
Dimensions — Height 20.32 cm | 8.0 in
Dimensions — Weight 0.45 kg | 1.0 lbs
Power 2 Standard AA batteries for 40+ hours of operation
Recorder 15 MB recorder
Good for 750+ casts during typical use
Sample Rate 5Hz