Smart Marine Navigation Aid System – Consolidated Project Documentation
Date: 29 July 2025

1. Executive Summary

This document unifies the full technical package for the Smart Marine Navigation Aid System — a dual-processor (Arduino Uno R3 + Raspberry Pi 4B) platform that delivers GPS-based positioning, environmental monitoring, collision-risk prediction and standards-compliant maritime data exchange.

2. Project Scope & Objectives

• Develop an integrated navigation aid that fuses sensor inputs with real-time processing.
• Achieve IP67 environmental protection for all electronics and connectors.
• Implement NMEA 0183/2000 protocols for broad marine-electronics compatibility.
• Design cost-effective hardware (< £900 BOM) while matching professional-grade reliability.

3. System Architecture Overview

The design follows a dual-layer architecture:

• Sensor & Real-Time Layer: Arduino Uno R3 acquires wind, barometric, temperature and ultrasonic proximity readings via I²C and analog channels.
• Processing & Communications Layer: Raspberry Pi 4B performs GNSS decoding, collision-risk calculations (DCPA/TCPA), data logging and external comms over Wi-Fi, Ethernet and CAN (NMEA 2000).

4. Hardware Design & Specifications

Component	Key Specs	Notes
Arduino Uno R3	ATmega328P @ 16 MHz, 14 DIO (6 PWM), 6 ADC	Deterministic sensor polling
Raspberry Pi 4B (4 GB)	BCM2711 4-core 1.8 GHz, 4 GB RAM, Wi-Fi 5, GbE	Processing & network services
u-blox NEO-8M GNSS	GPS/GLONASS/Galileo/BeiDou, –167 dBm, 10 Hz	2.5 m horizontal accuracy
Environmental Sensors	Ultrasonic wind, MEMS barometer, RH/Temp	Marine-rated, UV-stabilised
Power	12 V DC input, 85 % efficient SMPS, Li-ion backup	20 W peak draw

5. Environmental & Navigation Sensors

• Wind: 0.01 – 60 m s⁻¹, ±3 % accuracy
• Pressure: 300 – 1 100 hPa, ±0.5 hPa
• Temperature: –40 °C – +70 °C, ±0.3 °C
• Humidity: 0 – 100 % RH, ±2 %

Sensor fusion delivers situational data at 1 Hz to the navigation algorithms.

6. Marine-Grade Enclosure (IP67) Design

• Material: HP MJF PA-12 (production) or PETG FDM (prototype)
• Form Factor: 160 × 120 × 55 mm internal; 4 mm walls
• Sealing: 2.5 mm silicone O-ring with 25 % compression via 304 SS M4 bolts
• Penetrations: 3× M12 IP68 cable glands, SMA bulkhead for GPS, ultrasonic sensor well
• Thermal: Conduction ribs limiting internal temp rise to 10 °C at 3 W load

7. Power Management Architecture

Dual-rail (5 V & 3.3 V) buck converters supply regulated power. Reverse-polarity, over-current and transient-voltage protection meet IEC 60945 guidelines. Optionally, a 20 Ah LiFePO₄ pack guarantees 17.8 h autonomy (normal load).

8. Communication Interfaces

• NMEA 0183: RS-422, 4 800 / 38 400 bps
• NMEA 2000: CAN @ 250 kb s⁻¹, PGN-based messaging
• Wireless: Dual-band 802.11ac for remote monitoring
• Ethernet: Shielded GbE for data logging & firmware updates

9. Collision Avoidance Algorithms

DCPA = |(r₂ − r₁) × (v₂ − v₁)| / |v₂ − v₁|
TCPA = (r₁ − r₂) · (v₂ − v₁) / |v₂ − v₁|²

A weighted risk index triggers visual/audible alerts when thresholds are breached.

10. Software & Data-Processing Workflow

• GNSS parsing (py-gps libraries)
• Sensor MQTT broker
• Collision-risk engine
• Web dashboard (Flask/Plotly) for live data & historical plots
• All code containerised via Docker for reproducible deployment

11. Testing, Validation & Field Trials

• Environmental: 24 h salt-spray @ 5 % NaCl, –10 °C ↔ 50 °C cycles
• Ingress Protection: IEC 60529 IP67 immersion (1 m, 30 min)
• Functional: 12 h coastal voyage logging; GNSS accuracy 2.7 m (95 %)

12. Cost Analysis & Commercial Viability

BOM £865 vs. commercial systems £2 k – £10 k. Projected retail price £1 200 yields ~40 % margin at 1 000-unit scale.

13. Future Enhancements & Scalability

• AI-driven collision prediction
• Satellite comms for offshore operations
• AIS transceiver integration
• Cloud-based fleet analytics

14. References & Standards Compliance

Complies with: NMEA 0183 v4.30, NMEA 2000 v3.000, IEC 60529 (IP67), IPC-A-610, COLREGS, STCW, ISO 12216 Cat C.

Technical Design Diagrams & Specifications

System Architecture Overview

The Smart Marine Navigation Aid System employs a dual-processor architecture combining an Arduino Uno R3 for real-time sensor acquisition and a Raspberry Pi 4B for advanced processing and communications. Multiple marine-grade sensors, GPS positioning and maritime protocols are integrated in a unified platform.

Hardware Component Integration

• Primary Data Bus: I²C @ 400 kHz for sensor communication
• GPS Interface: UART @ 9 600 baud for NMEA sentence reception
• Inter-processor Communication: SPI @ 1 MHz for data exchange
• Power Distribution: Multi-rail system with 3.3 V, 5 V & 12 V domains
• Environmental Protection: IP67-rated connectors and sealed interfaces

Marine Enclosure Design

• Material: Marine-grade aluminium alloy with anodised finish
• Sealing: O-ring sealed joints with silicone gaskets
• Mounting: Standard NMEA bracket compatibility
• Thermal Management: Passive cooling with internal heat-dissipation fins
• Accessibility: Quick-release cover for maintenance access
• Cable Management: Strain relief & waterproof connector systems

Power Management Architecture

• Input Voltage Range: 10.8 V – 15 V DC (12 V nominal)
• Efficiency: > 85 % across all operating modes
• Protection: Over-voltage, under-voltage & reverse-polarity protection
• Battery Backup: Automatic switchover for uninterrupted operation
• Consumption Monitoring: Real-time power usage tracking & alerts

Communication Interface Design

• NMEA 0183: RS-422 differential signalling at 4 800 / 38 400 baud
• NMEA 2000: CAN-bus implementation with 120 Ω termination
• Wireless: 2.4 GHz / 5 GHz Wi-Fi with marine-grade antenna optimisation
• Ethernet: Shielded gigabit connection for data logging & remote access

Environmental Sensor Integration

• Wind Sensors: Ultrasonic measurement with heated elements
• Pressure Sensors: Compensated silicon MEMS with 16-bit resolution
• Temperature / Humidity: Digital output with factory calibration
• Data Acquisition: 12-bit ADC with programmable-gain amplification

Integrated PCB Architecture

The integrated PCB combines the Arduino Uno R3 (ATmega328P, 5 V logic) and the Raspberry Pi Compute Module 4 (BCM2711, 3.3 V logic) onto a single marine-qualified board, marrying deterministic sensor handling with high-performance collision-avoidance processing.

Power Management Subsystem

Designed for 4.04 W – 20.19 W operation, the board accepts a protected 12 V DC marine feed and steps it down to multiple regulated rails:

• Primary Input: 12 V DC via reverse-polarity-protected connector (P-MOS IRFP4227) and TVS SMBJ15CA with EMI filtering
• 5 V Rail: LM2596S switch-mode regulator, 3 A max, with 1 000 µF + 100 nF filtering
• 3.3 V Rail: AMS1117-3.3 linear regulator, 1 A max, tantalum 47 µF + ceramic 10 nF decoupling

Voltage Level Translation

• Primary High-Speed Interface: SPI / I²C cross-domain communication through octal 74LVC245 transceiver, direction-controlled by the Pi
• UART Channel: BSS138 MOSFET-based bidirectional shifter supports full-duplex 115 200 bps serial exchange
• I²C Bus: Separate 5 V and 3.3 V buses interconnected via PCA9306 level shifter, preserving 3.3 V sensor integrity

Arduino Integration

• ATmega328P @ 16 MHz, external crystal (22 pF caps)
• Reset pull-up 10 kΩ, VCC/AVCC decoupled by 100 nF caps
• Analog Front-End: Precision AREF (MCP1541-3.0) + 100 Ω / 100 nF RC low-pass filters to combat marine EMI
• Programming Interface: Standard 6-pin ISP header with on-board level translation for 3.3 V-safe programming

Raspberry Pi Integration

• Compute Module 4 with high-density board-to-board connectors exposing all CM4 I/O
• High-speed signals (HDMI, USB, Ethernet) routed at 50 Ω single-ended / 100 Ω differential impedance
• GPIO protection: 100 Ω series resistors + PESD3V3L1BA ESD diodes

Marine Interface Subsystem

• NMEA 2000 CAN Bus: MCP2515 controller (SPI to Arduino) + MCP2562 transceiver + galvanic isolation (ADUM1201 + isolated DC-DC NME1212SC)
• GPS Module: U-blox NEO-8M on Pi UART, RF filtering, antenna switch, CR2032 backup for hot-start
• Sensor Hub: TCA9548A I²C multiplexer allows address conflicts & per-sensor power gating

Marine Protection & Environmental Hardening

• Conformal Coating: 50 – 75 µm silicone (Electrolube SCC3) on designated keep-out regions
• Sealed Connectors: Deutsch DT (power) & M12 (sensors) rated IP67
• Thermal Management: Copper pours, thermal vias, on-board DS18B20 temperature monitoring

PCB Stack-Up & Layout

Layer	Function
1	Components & high-speed routing
2	Continuous ground plane
3	5 V power (split analog/digital)
4	3.3 V power & low-speed signals
5	Isolated ground for sensitive circuits
6	Bottom-side components & finish routing

High-speed differential pairs are routed at 100 Ω ± 10 % and single-ended at 50 Ω to meet USB 2.0 & Gigabit Ethernet specs.

Manufacturing & Assembly

• Component Selection: All passives AEC-Q200 (−40 °C – +125 °C); capacitors X7R dielectric; resistors thick-film
• Assembly Process: SMT parts on top side; through-hole connectors for mechanical strength; conformal coating post-reflow

Testing & Validation

• Bed-of-nails access to power rails and critical nets
• Combined JTAG for CM4 and 6-pin ISP for ATmega328P

Cost Analysis

The integrated PCB adds £50–75 to the base system (≈ 6 – 9 %) while removing ~£25 worth of cabling and improving reliability, size and IP67 compliance.