Build a Central Marine Computer with Raspberry Pi: Monitor and Protect Your Boat

Transforming your boat’s monitoring and alert systems doesn’t require proprietary hardware or expensive marine computers. With a Raspberry Pi, a few affordable sensors, and free open-source software, you can build a reliable, expandable central marine computer that integrates navigation data, engine monitoring, solar power stats, tank levels, and even security features — all on a budget.

Whether you’re sailing offshore or tied up in a marina, your boat’s key systems can now be monitored, logged, and alerted directly to your phone or tablet.

Why a Central Marine Computer?

A well-designed marine computer consolidates all essential boat data into one interface. The benefits are immediate and powerful:

• Real-time alerts for temperature, bilge water, battery state, and more

• Customizable automations (e.g., turn on anchor light at sunset and off at sunrise, but only if the boat is stationary)

• Access to engine diagnostics and trend analysis

• Monitoring from anywhere, using tablets or phones

• Full support for NMEA 0183 and NMEA 2000, wired and wireless

• Display of all NMEA instrument data on custom dashboards

• Local, secure, and cloud-free solution

Core System Features

Below is a non-exhaustive list of what your system can do using real examples from the Smart Boat Innovations project:

✅ Bilge and Leak Detection

Wireless water sensors detect leaks near seacocks or bilge and trigger sirens or remote alerts.

✅ Engine Monitoring

Using one ESP32 microcontroller, you can wirelessly send multiple engine parameters to your marine computer:

• Coolant temp

• Thermostat temp

• Raw water elbow temp

• Alternator temp

• Oil pressure

• Tachometer (RPM)

• Fuel level

All data is logged and displayed. Alerts notify you of overheating, loss of oil pressure, or abnormal RPMs. For instance, alerts can be triggered when the raw water elbow reaches 42°C (indicating a blocked intake or impeller issue).

✅ NMEA Instrumentation

All NMEA data from your boat’s instruments is integrated and displayed in custom dashboards. This includes (but is not limited to):

• Depth

• Wind speed/direction

• GPS location

• Compass/heading

• Water temperature

• Boat speed

This enables real-time monitoring and smart automations, such as trim reminders based on wind direction or speed.

✅ Tank Level and Battery Monitoring

Fuel, water, grey water — all resistance-based tank sensors can be digitized using INA219 modules. Add state-of-charge and solar production monitoring with Victron BLE or shunt integrations.

✅ Anchor Alarm and GPS Tracking

Geofence-style anchor alarms without extra apps. It can trigger onboard sirens and send push alerts when drift is detected.

✅ Smart Automations

• Auto anchor light on at sunset/off at sunrise (only if the boat is stationary)

• Bathroom lights turn on with motion only at night

• Fans or blowers activate at engine over-temp

• Watermaker routine flush daily

• Custom alerts like “Wind speed limit exceeded — time to reef sails”

✅ Fire, Intruder & Siren Alerts

Wireless smoke detectors and indoor sirens allow you to detect fire, and notify crew or nearby vessels.

✅ Remote Access and Control

Monitor or control your systems from land. Turn on the bilge pump from your phone if your float switch fails — even when you’re away.

NMEA Compatibility

This is key. Your setup supports:

• NMEA 0183 over USB or Wi-Fi

• NMEA 2000 via USB or wireless via ESP32

This enables full compatibility with nearly all modern and legacy marine sensors and instruments — regardless of connection method.

🧰 Required Core Equipment – Central Marine Computer

These are the components for the core system that ties everything together:

• Raspberry Pi 4 or 5 (4GB+ RAM)

• A2-rated 32GB+ MicroSD card

• 12V to USB-C converter (regulated power)

• 4G router with external SIM (e.g., TP-Link MR6400)

• Zigbee USB dongle (Sonoff Zigbee 3.0 or equivalent)

• USB-to-Serial converter for NMEA 0183

• USB-CAN adapter for NMEA 2000

🔧 Optional Sensor Modules – For Expansion Projects

These low-cost add-ons enable specific monitoring functions:

📈 Engine Monitoring

• ESP32 microcontroller

• DS18B20 sensors (Coolant, thermostat, alternator, elbow)

• INA219 sensors (Oil pressure, fuel level)

• Optocoupler (Alternator pulse-based RPM sensing)

⚡ Energy & Solar

• Victron BLE integration (for MPPT solar controllers)

• Hall current Sensors

💧 Tank & Fluid Monitoring

• Resistive tank senders (fuel, water, grey water)

• INA219 voltage mapping for analog sensors

🚨 Safety & Security

• Zigbee water leak sensors

• Wireless indoor sirens

• Smoke detectors (Zigbee)

🔗 Automation Hardware

• Relay switches (for watermaker, horn, lights)

• Magnetic chain sensor (for anchor winch chain measurement)

🔄 Software Overview

This system runs Home Assistant, a powerful open-source automation hub that is:

• Free

• Customizable

• Locally controlled (no cloud dependencies)

• Accessible via smartphone, tablet, or web browser

Sensor data is integrated via ESPHome on ESP32 modules, Zigbee over USB, and direct USB/serial connections for NMEA data. This setup also supports over-the-air (OTA) updates to ESP32 devices.

🎥 Step-by-Step Video Series

Follow the full 26-part video series to build your marine computer step-by-step:

▶️ Smart Boat Innovations YouTube Playlist

💰 Total Cost: Approx. $400

This base setup includes everything you need to build a robust, expandable marine monitoring solution. New sensors or devices can be added anytime without changing the core.

Conclusion

A DIY central marine computer using a Raspberry Pi gives you:

• Full situational awareness

• Data-driven decision making

• Proactive safety and maintenance alerts

• Peace of mind — even when away from your boat

No proprietary software. No subscription fees. Just control, visibility, and reliability.

Ready to modernize your boat?

👉 Visit smartboatinnovations.com to get started.