Navis BGC Autonomous Profiling Float with Biogeochemical Sensors

Navis BGC Autonomous Profiling Float with Biogeochemical Sensors

Autonomous profiling float for Argo and other programs, with Sea-Bird CTD and Dissolved Oxygen sensor and WET Labs ECO Triplet fluorometer/backscattering sensor. Sufficient power for 250 CTD profile cycles to 2000 dbars.

(Photo by Christoph Gerigk © Sea-Bird Electronics)



A Navis autonomous profiling float with integrated optical Dissolved Oxygen sensor (SBE 63) and bolt-on WET Labs ECO Triplet is now available from Sea-Bird Scientific. The sensors take continuous measurements at 1 Hz through ascent, and provide high accuracy, resolution, and stability.

  • The SBE 41CP CTD measures conductivity, temperature, and pressure (depth). The pump-controlled, T-C ducted flow minimizes salinity spiking caused by mismatch of temperature and conductivity measurements.
  • The individually calibrated SBE 63 Optical Dissolved Oxygen sensor is integrated within the CTD flow path, providing optimal correlation with CTD measurements.
  • The ECO Triplet is three sensors in one, providing any combination of fluorescence (chlorophyll, CDOM, phycoerythrin, phycocyanin, rhodamine, or uranine) and backscattering (blue, green, or red) measurements. The Triplet is clamped to the float hull, and cabled to the end cap.

The carefully engineered anti-foul protection includes anti-foulant devices, a U-shaped flow path, and an integral pump. On the float’s ascent, as it approaches 10 to 5 dbars beneath the ocean surface, the pump turns off. The U-shaped flow path prevents sea surface oils and contaminants from being ingested while proceeding through the ocean surface skin and sitting at the surface during data transmittal. Between profiles the pump is off. The U-shaped flow path prevents water flow through the system caused by waves or currents; minute amounts of anti-foulant concentrate inside the conductivity cell to minimize bio-fouling.


Navis BGC Float Deployment in the Mediterranean (photo by Christoph Gerigk © Sea-Bird Electronics)


  • Temperature: ± 0.002 ºC initial accuracy, 0.0002 ºC/year stability
  • Salinity: ± 0.002 PSS-78 initial accuracy, 0.001 PSS-78/year stability
  • Pressure: ± 2 decibars initial accuracy, 0.8 decibars/year stability
  • Dissolved Oxygen: ± 3 µmol/kg or 2% initial accuracy, <1 µmol/kg/100,000 samples stability (20 ºC; sample-based drift)
  • Chlorophyll Fluorescence: ± 0.2% of full scale initial accuracy (relative to a specific monoculture of phytoplankton [diatom] grown in specific light/nutrient conditions)
  • CDOM Fluorescence: ± 0.3% of full scale initial accuracy (relative to Quinine sulfate dihydrate)
  • Backscattering: ± 0.2% of full scale initial accuracy (relative to polystyrene beads [2 µm ± 0.1 µm mean diameter])

Volume change: 1.7% (minimum fractional)

Depth rating: 2000 decibars

Communications: Iridium Transceiver 9523 -- RUDICS, circuit switched. Nominal transmission time 275 sec for 2000 dbar profile cycle (2 dbar bins of 1 Hz data)

Position: GPS, Garmin 15xL-W, mean acquisition time 20 sec

Park interval: 1 - 15 days

Materials: Aluminum hull, seamless natural rubber external bladders

Oil reservoir: 300 ml

Ballasting: Self-ballasting, 1 day to equilibrate

Weight in air: Less than 20 kg

Box: Stackable, export-compliant

Self-activation: Starts operating automatically on deployment, when pressure reaches user-programmable setpoint

Internal batteries: 4 packs of 3 DD lithium sulfuryl chloride cells (cannot ship in passenger aircraft; Class 9 Dangerous Goods). Each pack has 10.8 V open circuit voltage & 30 AH capacity; 1166 kJ (4664 kJ/4 packs).

Power consumption: 13 kJ for a 2000-dbar profile cycle

Power endurance: 250 2000-dbar cycles

Memory: CTD stores one 2000 decibar profile

Dimensions: Hull diameter 14 cm (5.5 inches), Ring diameter 24 cm (9.5 inches), Total length 167 cm (65.7 inches)

The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

How should I handle my CTD to avoid cracking the conductivity cell?

Shipping: Sea-Bird carefully packs the CTD in foam for shipping. If you are shipping the CTD or conductivity sensor, carefully pack the instrument using the original crate and packing materials, or suitable substitutes.

Use: Cracks at the C-Duct end of the conductivity cell are most often caused by:

  • Hitting the bottom, which can cause the T-C Duct to flex, resulting in cracking at the end of the cell.
  • Removing the soaker tube from the T-C duct in a rough manner, which also causes the T-C Duct to flex. Pulling the soaker tube off at an angle can be especially damaging over time to the cell. Pull the soaker tube off straight down and gently.
  • Improper disassembly of the T-C ducted temperature and conductivity sensors (SBE 25, 25plus, and 9plus) when removing them for shipment to Sea-Bird for calibration. See Shipping SBE 9plus, 25, and 25plus Temperature and Conductivity Sensors for the correct procedure.

Note: If a Tygon tube attached to the conductivity cell has dried out, yellowed, or become difficult to remove, slice (with a razor knife or blade) and peel the tube off of the conductivity cell rather than twisting or pulling the tube off.