STR1 & STR2 Radar Tank Level Senders

The Smarter Way to Monitor Boat, RV and Vehicle Tanks

Accurate tank-level monitoring is essential for boats, motorhomes, campervans and off-grid vehicles. Knowing the levels of fresh water, grey water, black waste, or fuel can make the difference between a relaxed journey and an unexpected interruption.

Traditional tank sensors can suffer from problems such as sticking floats, probe fouling, corrosion, inaccurate readings and calibration issues.

Blog Outline:

1. Simarine’s New STR1 and STR2

2. What’s the Difference Between the STR1 and STR2?

3. STR1

4. STR2

5. Why Use Radar for Tank Level Measurement?

6. Automatic Tank Height Detection

7. Custom Tank Calibration Using the Simarine Connect App

8. STR1 Specifications

9. STR2 Specifications

10. The Free Simarine Connect App

 

Simarine’s new STR1 and STR2

Simarine’s new STR1 and STR2 radar tank level senders take a different approach. Using high-precision micro-radar technology, the sensors measure liquid levels without ever touching the liquid. Mounted externally on the top surface of a plastic, composite, GRP and *metal tank, the STR radar signal penetrates the surface of a suitable tank while providing a low-profile, no-maintenance alternative to conventional tank senders.

*The STR1 and STR2 will work on metal tanks, but an adapter plate is required.

 

What’s the difference between the STR1 and the STR2?

The STR series consists of two radar-based tank level sensors designed around the same non-contact measurement technology.

Both models are designed to work through tank heights from 150 mm to 2,000 mm, with approximately 7 mm resolution and a near-field dead zone of approximately 40 mm at the radar face.

The key difference is how the sensor communicates the tank-level information:

STR1

The STR1 is the analogue version, designed to work with most existing analogue brands. The 240–33 Ω output is particularly useful for systems using the common European resistance standard, while the 0–190 Ω and 0–5 V outputs provide additional brand compatibility.

The STR1 can drive up to 3 analogue gauges simultaneously, and tank levels can also be viewed on a free Simarine app.

 

 

 

STR2

The STR2 is the digital version, using NMEA 2000 to communicate tank-level information with compatible marine electronics, chart plotters and multifunction displays.

This makes it relatively straightforward to choose the appropriate model based on the monitoring system already installed in your boat, RV or vehicle.

 

 

 

Why use radar for tank level measurement?

There are no moving parts, no float arm or mechanical components that can stick or wear. No contact with the tank contents, which means no maintenance. The sender is approximately 62 mm in diameter and 32.5 mm high, making it suitable for installations where space above the tank is limited.

The sensors should have a clear line of sight into the tank. It’s recommended to avoid locations above baffles, close to strong inlets and outlets, or areas where tank geometry could interfere with the radar reflection. Ideally, the sender should be positioned towards the centre of the tank and mounted on the top surface of a tank

 

Download the free Simarine Connect App available for Apple and Android smartphones

Automatic Tank Height Detection

One of the most useful features of the STR series is automatic tank-height detection. Rather than requiring a traditional empty/full calibration routine, the sender can automatically determine the tank height when there is some liquid present. The measurement can then be fine-tuned through the free Simarine Connect app.

This is especially useful if you’re looking for a simpler installation and commissioning process.

Custom Tank Calibration Using the Simarine Connect App

Not every tank has a perfectly regular shape. A tank may be wider at the bottom, have angled sides or contain internal geometry that means a simple percentage calculation does not accurately represent the actual volume.

The Simarine Connect app addresses this with multi-point tank calibration.

Users can configure the tank and add up to 100 calibration points, allowing the displayed level to be matched to the actual tank volume. This can be particularly valuable for irregularly shaped tanks.

STR1 at a glance

• Analogue tank-level output
• 0–190 Ω, 240–33 Ω and 0–5 V outputs
• All three analogue outputs available simultaneously
• Bluetooth configuration through the Simarine Connect app
• Firmware updates via Bluetooth
• Compatible with Simarine PICO
• 150–2,000 mm supported tank height
• Approximately 7 mm resolution
• 10mm tank wall thickness, plastic/ GRP
• 8–35 V DC supply
• Approximately 14–20 mA current draw at 12 V
• IP67 splash-proof housing
• 3-year warranty
• Designed and manufactured in Slovenia, EU

STR2 at a glance

• Native NMEA 2000 connectivity
• Fluid Level PGN 127505
• Dedicated NMEA 2000 backbone connector
• Bluetooth configuration through the Simarine Connect app
• Firmware updates via Bluetooth
• Designed for compatible modern MFDs and chartplotters
• 150–2,000 mm supported tank height
• Approximately 7 mm resolution
• 10 mm tank wall thickness, plastic / GRP
• 8–35 V DC supply
• Approximately 14–20 mA current draw at 12 V
• IP67 splash-proof housing
• 3-year warranty
• Designed and manufactured in Slovenia, EU

The free Simarine Connect App

• Bluetooth pairing
• Tank naming
• Tank height configuration
• Units and volume settings
• Calibration
• Device management
• Firmware updates
• Backup and restore functions