CEFAS26-115 ITT for a Small Autonomous Underwater Vehicle

Cefas currently uses hand deployable multi-parameter sondes (CTDs) for collecting water column data. With the advent of easy-to-use small AUVs we wish to supplement these programs with more autonomous data collection. We envision a platform which will collect data comparable with our current instruments, which can also operate fully autonomously for a period of hours while our staff conduct other activities. 3. Technical Requirement Cefas require one small autonomous underwater vehicle equipped with biogeochemical sensors to supplement our water quality monitoring efforts. 3.1 The vehicle will be capable of collecting marine biogeochemical observations to a depth of 250 m. 3.2 It will weigh no more than 20 kg in air and will be deployable by a single person by hand, from shore or small vessels. 3.3 It will be fitted with sensors meeting the following specifications. 3.3.1 Temperature: Range: 0°C to 35°C Initial accuracy: ±0.01° Resolution: 0.0005°C Time constant: ~1s Typical stability: < 0.002°C per year 3.3.2 Conductivity Range: 0–85 mS/cm Initial accuracy: ±0.003 mS/cm Resolution: 0.001 mS/cm Typical stability: < 0.02 mS/cm per year 3.3.3 Oxygen concentration Range: 0–500 µM Initial accuracy: ±2 µM Resolution: 0.1 µM Time constant: < 8 s Typical stability: < 0.5 % per year 3.3.4 Chlorophyll-a fluorescence 3.3.5 Optical backscatter / turbidity 3.3.6 The following optional sensors are of value: • fDOM • Photosynthetically active radiation (Cosine) 3.4 It will be capable of maintaining a fixed depth from the seabed. 3.5 It will be capable of repeatedly navigating a saw-tooth transect mission plan in the presence of horizontal currents up to 2 knots, while maintaining navigation performance. 3.6 It will have an endurance of no less than 5 hours under the stated conditions in this Specification. 3.7 Mission planning will be possible via software graphical user interface. 3.8 Surface communications will be provided; VHF or Iridium SBD are acceptable. 3.9 The vehicle wil