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Sealogger CTD
SBE 25plus

Print version     Current Manual (older manuals)      Reference Sheet     Configuration options & accessories

SBE 25plus Sealogger Profiling CTDSUMMARY


The SBE 25plus Sealogger is the ideal research-quality CTD profiling system for coastal, estuarine, and budget-minded deep-water deployments. The battery-powered 25plus records data in memory, eliminating the need for a large vessel, electro-mechanical sea cable, and on-board computer. The 25plus can also transmit data in real-time.

Compared to the previous SBE 25, the 25plus incorporates an electronics upgrade, mechanical redesign, and additional features, with 16 Hz sampling, 8 differentially amplified A/D input channels, 16-bit A/D resolution for auxiliary sensor channels, more power for auxiliary sensors such as nitrate (e.g., Satlantic SUNA) and CO2 sensors, 2 RS-232 data input channels, and 2 GB memory. Data in memory is uploaded via the external bulkhead connector or the internal USB connector (for fast upload of large data sets). Firmware upgrades can be downloaded through the communications port, without opening the CTD. The unique end cap design provides easy access to bulkhead connectors, simplifying the addition and removal of sensors from the package.


Temperature and conductivity are measured by the modular Sea-Bird SBE 3F and SBE 4C sensors. The SBE 5 Pump and TC Duct provide pump-controlled, TC-ducted flow, to ensure coordinated measurement of the same parcel of water. This significantly reduces salinity spiking caused by ship heave, and in calm waters allows slower descent for improved resolution of water column features. The integrated, temperature-compensated strain-gauge pressure sensor is available in 8 depth ranges to suit the operating depth requirement. The 25plus includes interface electronics for up to 8 voltage-output sensors (dissolved oxygen, pH, fluorescence, PAR, light transmission, optical backscatter, etc.) and 2 serial output (RS-232) sensors.


The 16 Hz scan rate provides very high spatial resolution of oceanographic structures and gradients, and recording endurance of up to 55 hours (without auxiliary sensors) with alkaline batteries. Simultaneous with recording, real-time data can be transmitted directly to a PC serial port (transmission distance dependent on number of auxiliary sensors, baud rate, and cable properties; serial output sensor data cannot be transmitted). Recorded data are transferred via RS-232 or USB to a PC for processing. External power and two-way real-time communication over 10,000 meters of single-core, armored cable can be provided with the SBE 36 CTD Deck Unit and the Power/Data Interface Module (PDIM).

The SBE 25plus is easily integrated with an SBE 32 Carousel Water Sampler or SBE 55 ECO Water Sampler. Both real-time and autonomous auto-fire operations are possible with any Sea-Bird CTD / Water Sampler system.


A standard SBE 25plus is supplied with plastic housing and SBE 5P pump for depths to 600 m, SBE 3F temperature sensor, SBE 4C conductivity sensor, strain-gauge pressure sensor (8 ranges), T-C Duct, 2 GByte FLASH memory, 12 D-size alkaline batteries (Duracell MN 1300, LR20) in a battery pack, glass-reinforced epoxy bulkhead connectors, and stainless steel cage.

Options and accessories include:


Seasoft V2, our Windows 2000/XP software package, is included at no extra charge. Its modular programs include:



  Measurement Range Initial Accuracy Resolution
0 - 7 S/m 0.0003 S/m 0.00004 S/m
-5 to +35 0.001 0.0003
Pressure 0 to 20 / 100 / 350 / 600 / 1000 / 2000/ 3500 / 7000 meters 0.1% of full scale range 0.002% of full scale range

Memory: 2 GByte non-volatile FLASH memory (~20 hours of data from T, C, P, and 8 auxiliary voltage sensors; does not include auxiliary serial sensor data)

Data Storage:
Recorded Parameter Bytes/Sample
T + C + P 10
each external voltage sensor 2
auxiliary RS-232 sensor sensor dependent

Internal Batteries: 12 alkaline D-cells (Duracell MN1300, LR20) 55 hours profiling (no auxiliary sensors)

External Power Supply: 14 - 20 VDC; consult factory for required current

Power Requirements:
Sampling: 95 mA
Pump (SBE 5T or 5P): 150 mA
: 70 mA
: 70 A
(powered by internal batteries), 175 A (powered externally)

Auxiliary Voltage Sensors:
Auxiliary power out: 12 VDC, up to 1.2 A across all channels (1 A maximum per channel)
Voltage sensor: 0 - 5 VDC, 16 bit resolution

Housing Materials, Depth Rating, and Weight:

Depth Rating Housing Material Weight in air
(with pump and cage)
600 m (1950 ft) acetal copolymer plastic TBD
6800 m (22,300 ft) 7075 aluminum 22.5 kg (50 lbs)


Documentation -- manual, photos, technical papers, application notes, etc.

Sales Information -- options, accessories, cables, mount kits, spares, etc.

Software -- components of Seasoft V2

Links to Other Instruments of Interest

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Specifications are subject to change without notice.

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