Undercurrent: RC Boat to Submarine Phase 2

Summary

This project addresses that gap by converting an off‑the‑shelf RC boat into a functional, depth‑capable submarine using readily available components, open‑source microcontrollers, and accessible design tools. The scope includes redesigning the hull to support waterproofing, integrating a ballast system for controlled diving, and developing a multi‑Arduino control architecture capable of managing pumps, sensors, and propulsion. SolidWorks is used to model structural modifications and 3D‑printed components, while ThinkerCad provides a virtual environment for simulating electrical circuits before physical assembly.

Commercial RC submarines and underwater robotics platforms are often expensive, limiting access for students, educators, and early‑stage researchers. By demonstrating that a functional, depth‑capable submarine can be built from an affordable RC boat and readily available components, this project lowers the financial barrier to hands‑on learning in marine engineering, robotics, and control systems.

Technical Approach/Methodology

1.System Architecture Development

The system architecture development began with defining the functional requirements for both surface and submerged operation, focusing on navigation, depth control, stability, and communication. SolidWorks was used to model the hull, ballast tank, internal support structures, and component mounting points. In parallel, system block diagrams were created to map electrical and control interactions, ensuring compatibility between sensors, pumps, microcontrollers, and communication modules.

2. Mechanical Subsystem Design

The mechanical subsystem design centered on modifying the RC boat hull to support waterproofing, internal ballast integration, and structural reinforcement. Internal support walls and the ballast tank were 3D‑printed using strong, water‑resistant filament, and sand ballast was added to lower the waterline and enhance submerged stability. Propulsion components were integrated with careful alignment to maintain efficient thrust and maneuverability in both surface and underwater modes.

3. Electrical Integration & Circuit Simulation

For electrical integration and circuit simulation, ThinkerCad was used to model wiring layouts, pump control circuits, sensor interfaces, and power distribution. The system incorporated water sensors for leak detection and ballast fill‑level monitoring, dual pumps for rapid ballast intake and discharge, a 12V battery to supply adequate power, and motor drivers with sealed connectors and waterproof wiring paths. Virtual validation helped identify and resolve potential electrical issues before physical assembly.

4. Control System Development

Control system development implemented a dual‑Arduino architecture, with an onboard Arduino Nano managing pumps, sensors, and propulsion in real time, while an external Arduino Uno handled communication with the computer and user interface. Wireless transmitter/receiver modules were added to reduce tethering and improve mobility. Control algorithms were programmed for surface navigation, ballast‑based diving and resurfacing, and depth‑holding stability, with a potentiometer enabling fine‑tuned pump speed modulation for precise ballast control.

5. Prototyping, Assembly & Waterproofing

During prototyping and assembly, waterproofing strategies such as sealed gaskets, protective flotation for the control unit, and leak‑detection sensors were applied. Dry‑bench tests were conducted to verify subsystem functionality before any water exposure. Finally, controlled pool tests were performed to evaluate waterproof integrity, pump performance, ballast responsiveness, stability during transitions between surface and submerged modes, wireless communication reliability, and overall system integration.

Outcomes

The final system demonstrated strong electrical performance, with every component of the circuit operating as intended. The dual DC pumps provided reliable bidirectional water transfer, and the push‑button controls consistently toggled between sinking and rising modes. The potentiometer offered smooth, precise adjustment of pump flow rate, while the water‑level sensor accurately detected tank fill status. LED indicators responded correctly to both pump direction and sensor activation, giving clear real‑time feedback during testing. Mechanically, the ballast system required additional refinement; the boat needed more weight than expected, leading our team to add extra sand and eventually small metal weights to achieve proper submersion. Some sealing improvements were also necessary, as minor leaks affected stability during extended trials. Despite these challenges, the overall outcome was promising: the vessel performed well on the surface, and with a fully charged RC battery, the team was close to demonstrating complete underwater operation. With more time for iterative testing, the system could have fully validated its submerged capabilities.

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