Overview

The Garmin GST 43 is a thru-hull speed and water-temperature transducer built to retrofit an existing Nexus 43 mm thru-hull transducer (TH43). It reads water speed and temperature at the hull, and when it is paired with a GST 10 it can place that data onto an NMEA 2000 network for display on compatible Garmin chartplotters and instrument displays.

This is a practical replacement when you already have the Nexus 43 mm thru-hull fitting in place and want to keep the same hull opening while updating the sensor. Because it is a thru-hull installation, plan for a below-waterline mounting location where the sensor can stay clean and free of turbulence.

Key features

• Reads water speed and water temperature from a thru-hull sensor location
• Fits a 43 mm thru-hull retrofit commonly used for the Nexus TH43 sensor
• Supports NMEA 2000 network integration when used with a GST 10 adapter
• Allows speed and temperature data to be shown on compatible Garmin chartplotters and instrument displays
• Useful for upgrading older speed and temperature sensing without changing the existing 43 mm hull fitting

Variants

This product is offered in multiple configurations based on whether the GST 10 adapter is included.

The transducer function and 43 mm thru-hull retrofit fit remain the same; the difference is whether the package includes the GST 10 for NMEA 2000 network connection.

• 010-04284-00: Includes GST 10: Yes. This configuration includes the GST 10 so the transducer data can be shared on an NMEA 2000 backbone and viewed on compatible networked displays.
• 010-04283-00: Includes GST 10: No. This configuration is supplied without the GST 10; speed and temperature data still require a compatible interface to be shown on an NMEA 2000 display.

Compatibility and fit

The GST 43 is sized for a 43 mm thru-hull transducer retrofit and is intended as a replacement for the Nexus TH43 style installation. Confirm the existing thru-hull fitting size and the sensor style before ordering, especially on boats where the original fitting is older or has been modified.

As with any below-waterline sensor, check access to the inside nut area and cable routing space before starting. The sensor location matters for stable speed readings, so areas with clean flow are preferred over spots close to strakes, intakes, or other hull features that disturb water flow.

Network and display integration

When connected through a GST 10, the GST 43 can feed speed and water temperature onto an NMEA 2000 network so the information is available anywhere on the backbone. This is useful when your navigation display and your instrument display both need the same speed and temperature data.

On a mixed system, it helps to confirm which device will be used to display and manage sensor settings so you do not end up with duplicate sources for temperature or speed on the network.

Installation and setup

Thru-hull work is best handled with the boat out of the water and with proper sealing practices for below-waterline fittings. If you are replacing an existing TH43-style sensor, you will typically remove the old insert and fit the new transducer into the same 43 mm housing location, then route the cable to the connection point for the GST 10 or other interface.

Secure the cable where it cannot chafe, keep it away from sharp edges and moving parts, and leave a service loop so the sensor can be removed later for cleaning or inspection.

Use on board

This sensor is a good match for sailboats and powerboats that want speed-through-water and water temperature available on modern displays, especially when upgrading from a Nexus TH43 installation. Speed-through-water is commonly used for sailing performance data and current awareness, while water temperature is useful for fishing, seasonal navigation, and general situational awareness.

Maintenance and care

Like any hull-mounted sensor, performance depends on keeping the sensing area clean. Inspect it during routine haul-outs, remove marine growth as needed, and check the cable and sealing area for wear.