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Star-Oddi DST CTD (Conductivity, Temperature and Depth)

Manufacturer: Star-Oddi
Availability: Usually ships in 1-2 weeks, on request only, no refunds
Star-Oddi DST CTD, salinity, conductivity, temperature and depth logger. Small and economical salinity logger. Easy to mount on gear. For use on subsea gear and moorings for long-term oceanographic studies. Adding Star-Oddi’s protective housing offers flexible mounting options and added protection.

Price (exc. VAT) €1,304.96

Price (inc. VAT) €1,579.00

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Conductivity, Temperature and Depth Logger

Small and economical salinity logger. Easy to mount on gear. For use on subsea gear and moorings for long-term oceanographic studies. Adding Star-Oddi’s protective housing offers flexible mounting options and added protection.

Key features

  • Smallest CTD salinity logger on the market
  • Flexible mounting with protective housing
  • Different ranges, high or low conductivity
  • Depth sensors for shallow to deep ocean
  • On/off saltwater switch for saving memory

Smallest CTD on the market

This small autonomous salinity probe DST CTD measures and records conductivity, temperature and pressure. In addition to the three measured parameters the software calculates and displays salinity values and velocity in graphical and tabular form upon data conversion. It is only 50 mm in length and 15 mm width. Due to its small size it is easy to mount it on various gear and nets.


DST CTD is small and economical when compared to bulkier CTDs on the market. The CTD salinity measuring device is used for a variety of studies including:
  • Oceanography and hydrography - long term stationary monitoring or surveying
  • Fisheries research - CTD attached to fishing gear
  • Data collection on underwater vehicles – small sized CTD is an advantage.
  • For using the CTD on fish and marine animals, click here.

Flexible mounting with protective housing

A plastic protective housing is available, recommended when fastening the logger to subsea gear and moorings.

Depth sensors for shallow to deep ocean

Customers choose between depth calibration ranges up to 100 m, 500 m, 1200 m or 2400 m. The shallower the range the better the depth resolution and accuracy.

On/off saltwater switch for saving memory

It is possible to purchase the logger with a saltwater switch. This optional configuration and saves on the memory capacity, by only recording data when in saltwater. This on/off switch version is ideal for use on fishing gear, or ROVs to stop recordings when gear is on deck and automatically start again when submerged.

Conductivity cells are part of the logger housing

The conductivity sensor electrodes are located inside a small cup at the end of the logger housing. The pressure sensor for the depth measurements is located at the membrane and temperature sensor close to the membrane.

Choose between different conductivity ranges, up to 63 mS/cm

When ordering the DST CTD you can select between four conductivity ranges:
  • 13-63 mS/cm
  • 13-50 mS/cm
  • 3-37 mS/cm
  • 0.3-5 mS/cm

Don’t know your applicable conductivity range?

The suitable range depends on the minimum and maximum salinity and temperature in the area where the loggers will be used. Provided with that information we can recommend a suitable range.
You can also calculate the most suitable conductivity range for your study with the free SalCalc conductivity calculator software.

Conductivity sensor accuracy

Conductivity accuracy is specified better than +/-4% of the selected range. As an example it is +/-1.48 for the 13-50 mS/cm range.

Simple in Use, From Setup to Data Retrieval

The logger and the accompanying items are designed for ease of use throughout the research process, from setting up the logger, attaching it, to retrieving and analysing the data. The CTD logger is supported by the SeaStar software and a Communication Box which have to be purchased with the first order.

Programming the Logger

To launch the CTD probe for measuring it is placed into the Communication Box interface that connects with a USB cable to a PC computer. In the SeaStar software, the user sets the start time, start date and sampling interval before starting the logger in measurement mode. The logger synchronizes its internal clock with the date & time on the computer being used.

Single or multiple intervals

There are two modes for sampling, either at a single interval throughout the period or multiple intervals. When choosing multiple interval programming it is possible to define up to seven different intervals and a number of measurements for each interval. Shifting between wide and narrow intervals can help in extending the measuring period due to memory limitation and have more frequent measurements during certain time periods. 

Memory and Battery Life Calculations

The software automatically calculates when memory fills up based on certain interval settings, making it easier for the user to decide how to program the logger. Estimation on battery consumption during that time period is also calculated.

Uploading the Data

After recovering the logger, it is inserted into the communication box and the recorded data is uploaded to the software. The results are displayed both in graphic and tabular form and the data can be exported to other programs. The time series data shows each measurement with its own time stamp.

Low energy consumption

After data retrieval the logger can be reused, as long as the batteries last. Battery life estimation is always reported upon connection with the logger. Due to the low energy consumption circuitry design the battery life is long, but actual lifetime depends on usage and sampling interval used.

Communication box

The Communication Box serves as an interface between the DST and a PC computer. It is used for connecting to the DST, when starting the logger and retrieving data. DST is inserted into the hole of the box for wireless communications. The box comes with a USB cable for connecting to a PC computer.

SeaStar software

The SeaStar software for Windows is needed to operate the DST. Data is displayed in a graph and table. The time series data file can be opened in other programs. An installation product key is provided when ordering the software, for online downloading.

Plastic protective housing

Star-Oddi offers protective housing for the DST to give more flexible mounting options and to protect the data logger when used under more harsh environmental conditions. When used as a stand alone logger it can be attached fishing gear, moorings, deployment lines or other equipment. It has attachment points (6 mm in diameter) on top and bottom. The protective housing is made of polyurethane (PUR) plastic. The housing dimensions are 75 mm in length x 30 mm in diameter. Weight is 50 g in air and 10 g in water.

Wire clip for plastic protective housing

Wire fasteners for DST protective housings. Ideal for fastening the equipment to fishing gear and long lines. The wire fasteners are made of non-corrosive stainless steel with a clip to ensure secure fastening. The length of the wires can be adjusted to fit the application.

Stainless steel protective housing for DST

Star-Oddi offers stainless steel protective housing for DST loggers (we recommend using them with a plastic housing to give extra protection). It is ideal when fastening to cables, moorings or fishing gear. Dimensions of the steel housing are 125 mm x 42.4mm. Thickness is 3.25mm and it weighs 356 g in air.
Sensors Conductivity (salinity), temperature, pressure (depth)
Size (Diameter x Length) 15 mm x 50 mm
Housing Material Alumina (Ceramic)
Weight (in Air/in Water) 21g/13g
Data Resolution 12 bits
Conductivity Ranges Choose between: 13 to 63 mS/cm, 13-50 mS/cm, 3-37 mS/cm or 0.3-5 mS/cm
Conductivity Resolution Range 13-63 mS/cm: 0.02 mS/cm
Range 13-50 mS/cm: 0.01 mS/cm
Range 3-37 mS/cm: 0.01 mS/cm
Range 0.3-5 mS/cm: 0.002 mS/cm
Conductivity Accuracy Range 13-63 mS/cm: +/-2 mS/cm
Range 13-50 mS/cm: +/-1.5 mS/cm
Range 3-37 mS/cm: +/-1.5 mS/cm
Range 0.3-5 mS/cm: +/-0.3 mS/cm
Salinity Range Depends on conductivity and temp. range (consult with Star-Oddi)
Salinity Resolution *Range 13-63 mS/cm: 0.01 PSU
Range 13-50 mS/cm: 0.01 PSU
Range 3-37 mS/cm: 0.01 PSU
Range 0.3-5 mS/cm: 0.0005 PSU
Salinity Accuracy *Range 13-63 mS/cm: +/-1.5 PSU
Range 13-50 mS/cm: +/-1 PSU
Range 3-37 mS/cm: +/-1 PSU
Range 0.3-5 mS/cm: +/-0.1 PSU
Saltwater Switch Available upon customer request (DST CTD logic)
Temperature Range -1°C to +40°C (30°F to 104°F)
Temperature Resolution 0.032°C (0.058°F)
Temperature Accuracy +/-0.1°C (0.18°F)
Temperature Response Time Time constant (63%) reached in 20 sec.
Standard Depth Ranges 1m-100m, 5m-500m, 5m-1200m, 10m-2400m
Depth Resolution 0.03% of selected range
Depth Accuracy +/-0.6% of selected range
Depth Response Time Immediate
Memory Type Non-volatile EEPROM
Memory Capacity 87,217 measurements per sensor
Memory Mangement Custom programming
Sampling Interval User specified in second(s) minute(s), or hour(s)
Minimum Measuring Interval 1 second
Multiple Intervals Option Up to 7 different intervals
Data Retention 25 years
Clock Real time clock. Accuracy +/-1 min/month.
Communications Communication Box, wirelss transmission when DST sits in the box. Connection to PC: USB cable.
Attachment Hole 0.9 mm (diameter)
Battery Life 4 years**
Replaceable Battery No
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