Sula 2 Light Unmanned Surface Vessel

Sula 2 is a battery-electric catamaran unmanned surface vessel, 1.6 m long, that carries 50 kg. It takes the survey and monitoring payloads of a portable boat with more weight to spare, such as a Seafloor HydroLite single-beam sounder, a SonTek RiverSurveyor M9 ADCP, a YSI EXO2 water-quality sonde or a side-scan, on lakes, rivers, harbours and sheltered inshore water. It works at 1.5 m/s and reaches 6 m/s at maximum speed. We configure each boat to order, with RTK GNSS position and dual-antenna heading as standard.

Platform specification

	Sula 2
Length × beam × height	1.6 × 1.2 × 0.6 m
Draught	30 cm
Mass	45 kg including battery
Payload	50 kg
Hull and propulsion	Carbon-composite catamaran; brushless DC electric propulsion
Endurance	5 h at working speed
Working speed	1.5 m/s (2.9 kn)
Maximum speed	6 m/s (11.7 kn), for 1–2 h
Wind and wave rating	Wind resistance level 5; 1.5 m wave
Water	Lakes, rivers, reservoirs, harbours and sheltered inshore water, within the stated sea state
Comms	4G and radio link; data and image to 5 km
Standard navigation	RTK GNSS position with dual-antenna heading
Optional GNSS-denied navigation	Gap bridging

Payloads Sula 2 takes

All payloads are configured to order and integrated per boat, within 50 kg.

Payload	Example models	Mount	Note
Single-beam echo sounder	Seafloor HydroLite, HydroLite Plus; Bathylogger BL200	Hull	Fits within Sula 2’s 50 kg payload.
ADCP	SonTek RiverSurveyor M9, S5; Teledyne RDI RiverPro, RiverRay; Nortek Signature VM	Hull	River discharge and current profiles. An M9 weighs 2.3 kg and an S5 1.1 kg in air.
Water-quality sonde or sampler	YSI EXO2, EXO2s; Aquaread AP-7000; In-Situ Aqua TROLL 600; Eureka Manta+ 35	Hull	A full sonde weighs a few kg, so the kit fits with room to spare.
Side-scan sonar, hull-mounted	Cerulean Omniscan 450 SS; DeepVision hull-mount 340/680	Hull	Bracket-mounted.
Multibeam, compact integrated head	Cerulean Surveyor 240-16 (IMU built in)	Hull	A compact head only. Survey-grade multibeam with a separate INS starts at Sula 3.
Fixed camera, radar, AIS	AIS Class B transponder	Mast	Fits within Sula 2’s 50 kg payload.

Where Sula 2 stops. Step up to Sula 3 for survey-grade multibeam with its own motion reference or survey INS and a sound-velocity profiler, a light towed side-scan, a stabilised thermal camera or EO/IR gimbal, or jamming resilience. Towed magnetometers start at Sula 5. Step down to Sula 1 when one person needs to carry the boat.

Applications

• Reservoir, lake and river bathymetry. Single-beam soundings tied to RTK for sediment surveys, with a 5 h mission at working speed.
• River gauging. ADCP discharge and current profiles on rivers.
• Water-quality monitoring and sampling. A multiparameter sonde and bottle samplers on lakes, reservoirs and rivers.
• Harbour and marina depth checks in sheltered water. Along quay walls, where reflections and a partial sky degrade the fix, gap bridging is designed to keep the boat on its line (integration available).
• Side-scan imaging of the bed in harbours, rivers and lakes, from a hull-mounted sonar.
• Small-area multibeam mapping with a compact integrated head, where a full survey-grade system is more than the job needs.

Sula 2 works in lakes, rivers, harbours and sheltered inshore water, for 5 h per mission at working speed.

Navigation

Standard: RTK GNSS position with dual-antenna heading, from a survey-grade GNSS heading receiver with light inertial (MEMS) aiding. The RTK correction feed comes from a base station on site or from network corrections over mobile data. On a 1.6 m hull the two antennas sit close together, so the hull’s length limits the heading baseline.

Option: GNSS-denied navigation, gap bridging. A tactical-grade MEMS inertial unit, a standard-accuracy Doppler velocity log (DVL), and the dual-antenna RTK GNSS receiver with raw data logged for post-processing (PPK). It is designed for outages of seconds to minutes under bridges, in culverts and beside structures and quays, and a filtered anti-jam antenna is an optional addition. Jamming resilience, for regions with deliberate jamming and subject to export licensing, starts at Sula 3.

GNSS integrity monitoring is an option with gap bridging; it is configured per boat (integration available), and integration with the autopilot is available. DVL bottom-lock needs the seabed within range, which means shallow water. More on the solutions: GNSS-denied USV navigation.

Integration and support

Integration	Payload fitted, wired and calibrated on the hull, with sensor offsets and parameters set and the RTK correction feed configured. Autopilot integration is available.
Delivery	Commissioning on your water, operator training, and support from our UK and EU teams.
Ordering	Configured to order, quoted per boat.

Questions and answers

How much payload does a light USV carry, and for how long?

Sula 2 carries 50 kg. It runs 5 h at its working speed of 1.5 m/s (2.9 kn), and 1–2 h at its maximum speed of 6 m/s (11.7 kn).

Can a 1.6 m USV carry a multibeam echo sounder?

Only a compact integrated head with its IMU built in, such as the Cerulean Surveyor 240-16. Survey-grade multibeam with a separate motion reference or INS and a sound-velocity profiler needs a stable mount and steady power, which Sula 3 provides.

Can a light USV take GNSS-denied navigation?

Yes, gap bridging: a tactical-grade MEMS inertial unit, a standard-accuracy DVL and a dual-antenna RTK GNSS receiver with PPK logging, for outages of seconds to minutes. Jamming resilience, with a multi-element CRPA and a tactical-grade fibre-optic-gyro inertial unit, starts at Sula 3.

Can a light USV tow a sensor?

Towed sensors start at Sula 3, with a light side-scan towfish. Sula 2 takes a hull-mounted side-scan. A towed magnetometer such as the Geometrics G-882 starts at Sula 5.

What water is a light USV built for?

Lakes, rivers, reservoirs, harbours and sheltered inshore water. Sula 2 is rated for wind resistance level 5 and a 1.5 m wave.