SonTek CastAway CTD
The SonTek CastAway®-CTD is a compact, handheld conductivity, temperature and depth profiler designed for rapid profiling of lakes, rivers, reservoirs, estuaries and coastal waters.
Simple to deploy and requiring no external pump, the CastAway-CTD provides high-resolution profiles of conductivity, temperature, salinity, sound speed and depth to depths of up to 100 m. Integrated GPS, an onboard colour display and wireless data transfer make it particularly well suited to fast, efficient field surveys.
Key Features
Conductivity, temperature and depth (CTD) profiling
Profiling depth up to 100 m
5 Hz sampling rate
Salinity accuracy of ±0.1 PSU
Temperature accuracy of ±0.05°C
Six-electrode flow-through conductivity cell
Fast-response temperature sensor
Integrated GPS position and time referencing
Onboard colour LCD for immediate profile review
Bluetooth wireless data transfer
No external pump required
Compact, rugged and easy to deploy
Rapid, High-Resolution CTD Profiling
The CastAway-CTD combines a six-electrode conductivity cell with a fast-response thermistor and pressure sensor to produce accurate, high-resolution water column profiles. Its hydrodynamic design allows the instrument to free-fall through the water at approximately 1 m/s while recording at up to 5 Hz.
Conductivity and temperature measurements are used to calculate parameters including salinity, specific conductance, density and sound speed, providing a detailed picture of changing water conditions throughout the water column.
Designed for Efficient Field Surveys
Unlike conventional CTD systems, the CastAway-CTD is completely self-contained and requires minimal setup. Each cast is automatically referenced by time and GPS position, with latitude and longitude recorded before and after the profile.
Data can be reviewed immediately in the field using the integrated display, allowing operators to inspect profiles of conductivity, temperature, salinity and sound speed against depth without returning to a computer.
Recorded data can then be transferred wirelessly to a Windows PC for further analysis, processing and export.
Typical Applications
The SonTek CastAway-CTD is suitable for:
Coastal and estuarine surveys
Lake and reservoir profiling
River and catchment studies
Salinity and stratification investigations
Environmental monitoring programmes
Hydrographic and bathymetric surveys
Sound-speed correction for sonar and hydrographic measurements
Research and educational applications
Its combination of portability, rapid deployment and immediate field data makes the CastAway-CTD particularly useful where multiple profiles or survey locations need to be completed efficiently in a single field campaign.
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 |
Specification | CastAway®-CTD |
|---|---|
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 |
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.