GDT™ 43 thru-hull transducer (depth/temperature) and NMEA 2000 adapter

The Garmin GDT™ 43 transducer is designed to accurately measure water depth and water temperature. It is an essential component for acquiring reliable marine data, integrating directly into existing NMEA 2000® networks.

The GDT™ 43 transducer operates at a sonar frequency of 200 kHz. It can reach a maximum depth of 275 meters (900 feet).

The GDT™ 43 transducer operates in temperatures ranging from -10°C to 70°C (14°F to 158°F).

The GDT™ 43 transducer dimensions are 42 mm in diameter by 86 mm in length (1.65 x 3.38 inches).

The GDT™ 43 transducer cable is 6 meters (19.7 feet) long.

The NMEA 2000 adapter measures 101.4 x 116.3 x 76.2 mm (4 x 4 19/32 x 3 inches).

The GDT™ 43 transducer is compatible with NMEA 2000® networks via the supplied adapter. It can also be connected to a Nexus system.

The GDT™ 43 transducer is specifically designed for hulls with a deadrise angle between 0 and 20 degrees to ensure optimal performance.

The NMEA 2000 adapter requires a 9 to 16 Vdc power supply.

To connect the GDT™ 43 transducer to a Nexus system, you must cut the transducer cable to the desired length and connect the wires to the depth port on the Nexus device. The wiring correspondences are as follows:

Black from the transducer to Black on the NexusRed from the transducer to Blue on the NexusShield from the transducer to Shield on the NexusThe white wire from the transducer must not be used.

Garmin uses NMEA 2000 micro-connectors on its devices, sensors, and T-connectors. These connectors are compatible with other NMEA 2000 micro-connectors, cables, and devices.

To install the GDT™ 43 transducer, you will need the following tools:

A drillA 43 mm (1 11/16 in) hole sawPossibly a 52 to 55 mm (2 1/16 to 2 3/16 in) hole saw for installations on fiberglass cored hullsMarine sealantSilicone greaseA cable cutterA metal file (for metal hulls)Materials such as fiberglass cloth and resin or a 43 mm cylinder with casting epoxy may be required to seal a fiberglass cored hull.

It is important not to install the GDT™ 43 transducer in the following locations:

Behind frames, reinforcements, fittings, water intake or discharge openings, or any other element likely to create air bubbles or turbulent water.
In the propeller wash path on single-propulsion boats.
At a location where it could be struck during launching, towing, or storage.
Near the edges of pronounced hull frames on powerboats and vee-hull vessels.

To prepare a fiberglass cored hull, follow these steps:

Drill a 3 mm (1/8 in) pilot hole through the hull from the inside. From the outside, use a 43 mm hole saw to cut only the outer fiberglass skin. From the inside, at the pilot hole, use a hole saw 9 to 12 mm (3/8 to 1/2 in) larger than the outer hole to cut the inner fiberglass skin and most of the core, without cutting the outer skin. Remove the cut core and inner skin. Seal the exposed core, either with fiberglass and resin, or with casting epoxy, to prevent water ingress.

Yes, it is crucial to properly seal the core of a fiberglass hull when installing the depth sounder. If the core is not sealed correctly, water can seep in and cause serious damage to the boat.

The NMEA 2000 network must be powered by a 12 Vdc source using a dedicated NMEA 2000 power cable. It is recommended to connect it via the ignition switch or another external switch to prevent draining the boat’s battery when not in use. The power cable must connect to the top of a T-connector.

It is not recommended to connect the NMEA 2000 network to a power source at more than one point without using a power isolator between the two connections. This prevents electrical issues and ensures the network operates correctly.

Yes, 120 ohm terminators must be installed at both ends of the NMEA 2000 backbone. Proper termination is essential to ensure signal integrity across the entire backbone and correct network operation.

Yes, the GDT™ 43 transducer can be used on keel boats, with specific mounting considerations:

On fin keel boats, the transducer must be mounted more than 25 cm (10 in) and less than 75 cm (30 in) ahead of the keel, and within 10 cm (4 in) of the centerline. On full keel boats, the transducer must be mounted at a slight angle pointing forward, not parallel to the centerline.