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Seagauge Wave & Tide Recorder
SBE 26plus

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SBE 26plus Seagauge Wave and Tide Recorder
SBE 26plus being secured in optional mounting fixture ‑
After installation at a mooring site, fixture allows removal and precise repositioning by a diver. Tools are not required, and there are no loose parts to misplace.



The 26plus combines Sea-Bird's non-volatile FLASH memory with a stable time base, precision thermometer, and Quartz crystal pressure sensor to provide wave and tide recording of unprecedented resolution and accuracy, along with high-quality temperature information. An input connector for an optional SBE 4M conductivity sensor is standard.

The 26plus integrates pressure samples to obtain water level measurements unaffected by wave action, and also independently burst-samples pressure at rates up to 4 Hz for wave amplitude calculation. Water level and wave burst sampling intervals and durations are programmable. The tide interval is programmable from 1 minute to 12 hours. The 26plus can continuously measure pressure (with Quartz pressure sensor), or can conserve battery power by removing power from the pressure sensor between tide measurements, with programmable pressure integration from 10 seconds to the entire tide interval. Temperature data is recorded with each tide integration. Waves are characterized by burst sampling, with programmable burst interval, number of samples per burst, and burst integration time. Logging start and stop times are programmable, allowing complete setup in the lab before deployment.

The large memory and low power requirements permit frequent water level recording and highly detailed wave characterization. For example, with Quartz pressure sensor, standard alkaline batteries, and optional conductivity sensor, a 445-day deployment can include water level measurements every 30 minutes (integrating pressure for the entire 30 minutes) and an 8.5-minute, 4 Hz wave-burst (2048 samples) eight times a day; a 670-day deployment can be achieved if pressure integration is limited to 11 minutes for each water level measurement.

The 26plus stores data in memory, and also outputs real-time tide data, wave data, and/or wave statistics. Binary upload capability at 115,200 baud allows for fast upload of data in memory upon recovery. Firmware upgrades can be downloaded via the serial interface, without opening the instrument.


A standard SBE 26plus is supplied with:

Options include:


The SBE 26plus is supplied with Seasoft for Waves, a comprehensive package of Windows programs including deployment planning, instrument setup and data retrieval, plotting, auto-spectrum and time series analysis, and statistics reporting.

Auto-spectrum plot of surface wind waves obtained from 1 burst sample of 1024 pressure measurements. Error bars correspond to 90% confidence intervals.


  Quartz Pressure
Strain Gauge Pressure
 Temperature (C)
High Accuracy Temperature (C)
Conductivity (S/m) 
Measurement Range 9 ranges, from
0 - 0.2 m (15 psia) to 
0 - 680 m (1000 psia)
4 ranges, from
0 - 20 m (45 psia) to 
0 - 600 m (880 psia)
-5 to +35 -5 to +35 0 to 7
Accuracy 0.01% of full scale 
(3 mm for 45 psia range )
0.1% of full scale 
(30 mm for 45 psia range )
0.01 0.002 0.001
Resolution Tide:
0.2 mm (0.008 in.) for 
1-minute integration;
0.01 mm (0.0004 in.) for 
15-minute integration
0.2 mm (0.008 in.) for 
1-minute integration;
0.01 mm (0.0004 in.) for 
15-minute integration
0.001 0.0001 0.00002
0.4 mm (0.016 in.) for 
0.25-second integration;
0.1 mm (0.004 in.) for 
1-second integration
0.4 mm (0.016 in.) for 
0.25-second integration;
0.1 mm (0.004 in.) for 
1-second integration
Calibration 0 psia to full scale pressure 0 psia to full scale pressure +1 to +32 2 +1 to +32 2 2.6 - 6 plus zero conductivity (air) 2
Stability 0.02% of full scale/year 
(6 mm for 45 psia range )
0.1% of full scale/year
(30 mm for 45 psia range )
Hysteresis 0.005% of full scale 
(1.5 mm for 45 psia range )
0.03% of full scale 
(9 mm for 45 psia range )
Stated values in mm for 45 psia pressure sensor. Scale for other ranges, multiplying by (sensor psia / 45 psia).
2 Measurements outside the specified calibration ranges at slightly reduced accuracy due to extrapolation errors.

Real-time clock: Quartz TCXO watch-crystal type 32,768 Hz; accuracy 2 ppm (5 seconds/month).
Battery-backed for minimum 2-year operation without main batteries installed.

Memory: 32 Mbyte Flash RAM

Data storage:
   Tide with temperature and time: 9 bytes/sample
   Tide with temperature, conductivity, and time: 12 bytes/sample
   Wave burst: 3 bytes/sample

Power supply:
   Internal: 12 alkaline D-cells, Duracell MN 1300, LR20 (standard) or 6 lithium DD-cells (Electrochem BCX85-3B76-TC)
   External (optional): 12 - 20 VDC

Housing: Acetal copolymer plastic to 600 meters

With alkaline batteries: 6.8 kg (15 lbs) in air; 2.3 kg (5 lbs) in water;
   Mounting fixture: 3.6 kg (8 lbs) in air; 1.4 kg (3 lbs) in water



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

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


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Specifications are subject to change without notice.

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