Robotics · Confined space inspection
A remotely operated surface vehicle for inspecting tunnels, culverts and confined waterways — where neither a submarine nor a wheeled robot can go.
Context
Underwater ROVs require sufficient depth to navigate. Wheeled inspection robots sink in mud and lose their view when water rises above the camera. In tunnels and culverts, water levels are often unpredictable — too shallow for a submarine, too deep or soft for wheels.
Confined spaces add another layer of constraint: CO, CO2, SO2, explosive atmospheres, unknown contents. Sending a person in is often not an option — legally or practically.
PPA needed a platform that operates at the water surface regardless of depth, doesn't sink in soft ground, and keeps its camera above water where the critical part of the inspection is: the tunnel ceiling and walls.
Why an airboat
An airboat sits on the surface. No minimum water depth required. Operates in conditions where a submarine would ground — a few centimetres of water is enough.
Mud, silt, uneven terrain — a wheeled robot gets stuck or capsizes. The airboat floats over all of it. Water level changes don't affect navigation or camera position.
In tunnel inspections, the ceiling and upper walls are the critical surfaces. A submerged camera misses them entirely. The airboat keeps the camera at the surface, pointing where it matters.
Build
The starting point was an existing RC airboat platform — retained for its hull geometry and buoyancy characteristics. Everything else was replaced or redesigned from scratch.
Control is handled by a Pixhawk flight controller paired with a Raspberry Pi 5, running ArduPilot with a Blue Robotics Cockpit-based software interface. Network connectivity uses the Blue Robotics switch topology — the same architecture as the underwater ROV, allowing shared tooling and operational familiarity for the operator.
Propulsion uses waterproof RC-grade brushless motors and ESCs with a custom-designed motor mount and rudder linkage. The electronics enclosure is fully custom-built, designed for the specific constraints of confined, potentially hazardous environments.
The camera is a 4K drone-grade unit, waterproofed inside a Blue Robotics cylinder with a custom mount and custom wiring run.
Technical details
Control system
Pixhawk + Raspberry Pi 5. ArduPilot firmware. Blue Robotics Cockpit interface.
Network
Blue Robotics switch topology. Tethered network over neutrally-buoyant cable.
Propulsion
Waterproof brushless motors + ESCs. Custom motor mount and rudder linkage.
Electronics enclosure
Fully custom-designed. Built for confined, potentially hazardous environments.
Camera
4K drone-grade unit. Blue Robotics cylinder enclosure. Custom mount and wiring.
Tether
Network cable. Neutral in salt water, slightly positive buoyancy in fresh water.
Planned evolutions
The current platform is designed with future capability extensions in mind. Two key evolutions are already defined based on operational requirements from PPA.