BoatTender Sentinel Core
Your Boat's Brain - Monitor Anywhere, Anytime
The first cloud-connected marine monitoring system that bridges analog sensors and NMEA 2000 networks. Professional monitoring at a price that makes sense.
NMEA 2000 Certified • Open Platform
Choose Your Connectivity
All Sentinel units share the same powerful monitoring platform. Pick the connectivity option that matches your cruising style.
Sentinel Core
WiFi Connectivity
Best For:
Marina and coastal cruising with WiFi access. Local monitoring on your boat's network.
Sentinel Coastal
LTE Connectivity
Best For:
Coastal cruising with cellular coverage. Monitor your boat from anywhere with internet.
Sentinel Offshore
Iridium Satellite
Best For:
Bluewater cruisers and offshore passages. Stay connected beyond cellular range.
Browser-Based Configuration
No Windows PC. No USB drivers. Just connect to Sentinel's WiFi and configure from any device with a web browser.
Analog Inputs Configuration
Configure fuel tanks, batteries, and temperature sensors with built-in gauge presets. Calibrate using simple empty/full values or 3-point curves.
Digital Inputs & Sensors
Set up engine RPM, bilge alarms, and OneWire temperature sensors. Helpful guides explain PPR ratios and configuration options.
Configure in Minutes, Not Hours
Drop-down sensor types, built-in presets for common gauges (VDO, Stewart Warner, etc.), and on-screen help make setup straightforward even for first-time installers.
What Competitors Don't Have
First-in-class features that set Sentinel apart from traditional marine monitoring systems
WiFi Configuration
No PC Required
Set up from your phone using any browser. No Windows PC, no USB drivers, no complicated software. Sentinel creates its own WiFi network.
Cloud Monitoring
First in Class
Check fuel levels, battery status, and temperatures from anywhere in the world via smartphone app. Competitors can't do this.
GPS Tracking
Built-In
Automatic position logging, trip history, and geofencing alerts. Know where your boat is and where it's been.
Satellite/LTE Addon
Offshore Peace of Mind
Optional modules enable critical alerts via satellite or cellular when offshore or away from WiFi. No competitor offers this.
OTA Updates
Future-Proof
New features delivered over WiFi. Your investment doesn't become obsolete. Open API for third-party integrations.
Test Mode Built-In
Verify Before Launch
380 Hz test output allows validation of RPM inputs without running the engine. No competitor has this.
Professional Features, DIY Price
For DIY Boat Owners
For Cruising Sailors
For Charter Operators
Technical Capabilities
How Sentinel Compares
| Feature | Sentinel Core | NoLand RS11 | Actisense EMU-1 | AlbaCombi |
|---|---|---|---|---|
| Configuration | Web browser (WiFi) | Windows PC (USB) | Proprietary | Ethernet + browser |
| Cloud Monitoring | Yes | |||
| GPS Tracking | Yes | |||
| Smartphone Access | Built-in WiFi | Requires router | ||
| Remote Alarms | Satellite/LTE | |||
| OTA Updates | Yes | Via Ethernet | ||
| Test Mode | Built-in | |||
| RPM Inputs | 4 digital | 2 | 2 | 2 |
| Dual Engine | Yes | Yes | Yes | Yes |
| Open API | Yes |
Technical Specifications
Inputs & Outputs
- • 4 analog voltage inputs (0-32V)
- • 13-bit ADC resolution
- • 4 digital pulse inputs (RPM, flow meter)
- • 1 OneWire temperature input (DS18B20)
- • NMEA 2000 certified output
- • Multi-engine support (instances 0-3)
Connectivity
- • WiFi 802.11 b/g/n (2.4GHz)
- • Built-in access point mode
- • Cloud connectivity (Cloud Edition)
- • GPS receiver (Cloud Edition)
- • Satellite addon support (RockBLOCK)
- • LTE Cat-M1 addon support
Power & Environmental
- • 12V/24V DC power via NMEA 2000 bus
- • Low power consumption
- • IP65 rated enclosure
- • Operating temp: -20°C to +60°C
- • Marine-grade construction
- • Corrosion-resistant housing
Platform & Updates
- • ESP32-based architecture
- • Over-the-air (OTA) firmware updates
- • Open API for integrations
- • Regular feature releases
- • Community-driven development
- • SignalK & OpenCPN compatible
Real-World Use Cases
Twin Engine Monitoring
Monitor both engines with 2× RPM + 2× coolant temp + 2× oil pressure using NMEA 2000 instances. All data displays correctly on any MFD.
Perfect for: Powerboats, catamarans, trawlers
Remote Monitoring at Anchor
Check your boat's systems from shore. Get instant alerts if battery voltage drops, bilge pump runs, or the boat drifts outside your geofence.
Perfect for: Cruisers, liveaboards, unattended vessels
Offshore Passage Making
Add the satellite module for critical alerts 500 miles from land. GPS tracks upload automatically when you reach WiFi, creating a complete voyage record.
Perfect for: Blue water cruisers, offshore racers
Charter Fleet Management
Monitor multiple vessels from one dashboard. Track fuel consumption, get maintenance alerts, and know immediately if a renter has engine trouble.
Perfect for: Charter companies, sailing schools, boat share programs
Frequently Asked Questions
Why not just use analog gauges?
Analog gauges work fine if you're always at the helm. But what about checking fuel before heading to the dock? Or knowing if your battery is charging while you're below deck? Sentinel gives you those gauges on your phone, plus alerts when something goes wrong.
I already have a multifunction display (MFD). Do I need this?
Perfect! Sentinel feeds data to your MFD and to your phone. Now you can check boat systems without turning on the chartplotter. Plus, cloud monitoring means you can check from home.
Is this difficult to install?
If you can wire a light switch, you can install Sentinel. Color-coded connectors, clear labeling, and built-in test mode make installation straightforward. Our video guides walk you through every step.
What if I'm not tech-savvy?
Sentinel's web interface is as simple as filling out a form. Pick your sensor type from a dropdown, enter a name, and click save. No programming, no command lines, no technical jargon.
How reliable is a startup product for critical boat monitoring?
Sentinel is built on proven, open-source foundations. NMEA 2000 compliance is certified. The ESP32 platform powers millions of IoT devices. And with OTA updates, we can fix issues and add features remotely. Plus responsive support.
When will it be available?
Sentinel Core is scheduled for release in Q1 2026. We're currently in final testing and certification. Sign up at boattender.app to be notified when pre-orders open.