SonTek CastAway-CTD Meter Review

Lightweight and easy to use, the SonTek CastAway offers a convenient 3-in-1 solution for measuring conductivity, temperature, and depth profiles. At a 5 Hz sampling rate, the CastAway is designed for up to 1 m/s free-fall through the water column.

With fast response and accurate conductivity, temperature, and depth measurements, the CastAway is ideal for thermocline and halocline profiling. The unit also reports salinity and speed of sound.

Environmental scientist, Katelyn Kubasky, holding the SonTek CastAway in front of the pond at the Fondriest Center for Environmental Studies. (Credit: Emma Jones / Fondriest Environmental)

The CastAway does not require user calibration, but an annual factory calibration is recommended. Before casting the device, users simply need to power it on and select if they’d like to see past measurements or take a point measurement. The included magnetic pen stylus is necessary for interacting with the device.

After each cast of the device, the user can view the data on the handheld color LCD screen immediately, showing the conductivity, temperature, depth, salinity, and speed of sound recorded in the cast. With a 15 MB memory, the CastAway can store data from more than 750 casts.

Compared to other CTDs on the market, the CastAway offers a small, handheld solution that is easy to transport and use in the field. The rugged, non-corrosive housing of the CastAway makes it drop-resistant and durable in harsh saltwater applications. An included polyurethane jacket makes the device easy to grip, even when wet.

While the CastAway comes with only a 15m casting line, the device is pressure-rated to depths of 100m and can easily be attached to a fishing rod or hand reel using one of the included carabiners. However, the instrument can also simply be attached to a sturdy rope as it is hydrodynamically designed to have a free fall rate of 1 m/s.

The CastAway provides convenient access to data in the field and through the CastAway Windows-based software. A built-in GPS receiver tracks both the time and location of each cast, displaying profiles in addition to mapping when the data is uploaded.

The SonTek CastAway offers convenience and accuracy for measuring conductivity, temperature, and depth profiles in harsh aquatic environments where durable design is essential.