Xylem Analytics UK - Let's Solve Water - Formerly YSI Hydrodata
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YSI CastAway™ CTD with GPS

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The YSI Castaway is the worlds first CTD to provide instantaneous profiles for temperature, conductivity, salinity, depth and speed down to 100m.

This product is RoHS Compliant
CastAway CTD front and back views.

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We have a large pool of water quality and hydrology instruments available to you for rental.


The YSI Castaway is a unique solution that measures temperature conductivity and depth at a rate of 5Hz down to depths of 100m. Due to its fast response time the Castaway is designed to be lowered at a freefall rate of 1m/s.

Equipped with in-buit GPS the YSI Castaway takes a position at the start of the cast and also at the end.  Sound speed velocity and salinity is calculated internally without the need to interface with a PC. Results are shown on an in-built graphical display as soon as it has surfaced and got its GPS fix.

Should you wish to look at the data in more detail then the internal data can be downloaded onto a PC and read using our free CastAway software via the internal Bluetooth negating the need for any cables.

The system can also be deployed very quickly and only needs to be calibrated annually.


  • GPS position, date, and time
  • Fast sampling and sensor response
  • Waterproof interface works in and out of the water
  • Bluetooth wireless communication
  • No user calibration needed
  • No tools, computers, or cables required

Key Applications

Best used in:

  • Coastal Oceanography
  • Drinking Water
  • Hydrology
  • Surveying/Hydrography
  • Aquaculture/Fisheries
  • Lakes
  • Arctic and Antarctic exploration

When needed for:

  • Saltwater Intrusion
  • Sound Velocity Profiles
  • Lake / Reservoir stratification
  • Field Sensor Verification
  • Drinking water aeration monitoring
  • Coastal Research
  • Teaching aid

*Patents Pending


Range Resolution Accuracy
Conductivity 0 – 100,000 µS/cm 1 µS/cm 0.25% ±5 µS/cm
GPS 10m
Pressure 0 – 100 dBar 0.01 dBar 0.25% of FS
Salinity (Derived) Up to 42 (PSS-78) 0.01 (PSS-78) 0.1 (PSS-78)
Sound Speed (Derived) 1400 –1730 m/s 0.01 m/s 0.15 m/s
Temperature -5 to +45°C 0.01°C 0.05°C



Internal BlueTooth Radio (Class 2);
Up to 10m range

Dimensions Diameter
2.8 in, 7.11 cm
8.0 in, 20.32 cm
1.0 lbs, 0.45 kg
GPS 10m accuracy; Acquisition time 1 min. from cold start
Power 2 Standard AA batteries for 40+ hours of operation
Recorder 15 MB recorder;
Good for 750+ casts during typical use
Sample Rate 5Hz




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