GMR™ 18 xHD3 Radom

The Garmin GMR 18 xHD3 radome is a compact and high-performance radar solution designed for reliable detection and seamless integration with Garmin navigation systems. It features xHD3 technology, delivering significant improvements over previous generations, including optimized signal processing for better target separation and clearer radar imagery.

Key features include:

A vertical beam width of 25 degrees (12.5 degrees above and 12.5 degrees below the radiating element), ensuring effective coverage even in rough seas.A compact 18-inch form factor, ideal for mid-sized boats where space is a critical factor.Ability to emit electromagnetic energy with optimized precision, making it perfect for coastal navigation, precipitation detection, and collision avoidance.

For optimal performance and safety, several factors must be considered when choosing the mounting location:

The radar must be mounted out of reach of people, with the vertical beam width above head height. It must be installed high above the vessel's keel line, with minimal obstructions between the vessel and the radar beam. The mounting surface must be flat, parallel to the vessel's waterline, and sufficiently robust to support the radar's weight. Avoid mounting the radar near heat sources (exhausts, lights), other electronic equipment, or cables carrying radio signals. GPS antennas must be positioned above or below the radar beam path. The radar must be mounted at least 1 meter (40 inches) from any transmission equipment and radio cables, and at least 2 meters (6.5 feet) from HF radios (SSB).

Yes, the GMR 18 xHD3 radome uses Garmin BlueNet™ network technology and is compatible with Garmin BlueNet devices as well as Garmin Marine Network devices.

For a Garmin BlueNet chartplotter or a Garmin BlueNet 20 switch: Connect the radome directly to an open network port using the included Garmin BlueNet cable.
For a Garmin BlueNet chartplotter using a Garmin BlueNet 30 gateway for Garmin Marine Network devices: It is recommended to connect the radome to the Garmin BlueNet side of your network for better performance and future updates.
For boats equipped only with Garmin Marine Network devices: You will need to use a Garmin Marine Network adapter cable (part number 010-12531-01) to connect the radome to your network.

To install the GMR 18 xHD3 radome, you will need the following tools:

A drillA 9.5 mm (3/8 in) drill bitA 32 mm (1 1/4 in) drill bit (optional, for cable routing)A 4 mm (5/32 in) Allen keyA 13 mm (1/2 in) wrench and a torque wrenchMarine sealant

Yes, it is possible to install the GMR 18 xHD3 radome on a cabin roof or hardtop, but it is crucial to take precautions to ensure optimal performance.

The beam transmitted by this radar extends vertically by 12.5 degrees from the horizontal midline. Therefore, you will need to raise the dome using a suitable stand or structure so that the beam clears the edge of the roof or hardtop. This prevents the transmitted energy from being reflected or absorbed by the surface, which is particularly important if the surface is metallic.

Yes, it is imperative to update the software of your Garmin chartplotter when you install the GMR 18 xHD3 radome. This update ensures compatibility and optimal operation between the radar and your navigation system.

Yes, the GMR 18 xHD3 radome is supplied with an included mounting template. This template must be used to drill the four 9.5 mm (3/8 in) mounting holes if you are not installing the unit on a pre-drilled Garmin radar mount.

It is critical to follow the template instructions precisely to ensure correct dimensions and avoid damaging your boat’s mounting surface.

The Garmin GMR 18 xHD3 radome stands out with significant improvements in signal processing. This technology enables better target separation and increased radar image clarity, delivering optimized performance compared to previous generations.

The GMR 18 xHD3 radome has a vertical beam width of 25 degrees. This includes 12.5 degrees above and 12.5 degrees below the radiating element, ensuring effective coverage even in swell conditions.

The Garmin GMR 18 xHD3 radome is ideally suited to medium-sized boats. Its compact 18-inch format makes it particularly suitable for vessels where space is a critical factor, while offering the benefits of xHD3 processing for coastal navigation, precipitation detection, and collision avoidance.

For installing the GMR 18 xHD3 radome, you will need the following tools:

A drillA 9.5 mm (3/8 in) drill bitA 32 mm (1 1/4 in) drill bit (optional)A 4 mm (5/32 in) Allen keyA 13 mm (1/2 in) wrench and a torque wrenchMarine sealant

For optimal performance, the GMR 18 xHD3 radar must be installed with several considerations in mind:

It must be mounted outside the reach of people, with the vertical beam above head height. Installation should be high above the vessel's keel line, with minimal obstructions between the vessel and the radar beam. The mounting surface must be flat, parallel to the waterline, and sufficiently robust to support the radar's weight. Avoid mounting near heat sources (exhausts, lights), horizontal spreaders, or mast rigging.

To avoid interference, follow these recommendations:

Mount the radar at least 1 m (40 in) away from any transmitting equipment.Keep the radar at least 1 m (40 in) away from cables carrying radio signals, such as VHF radios and their antennas.Maintain a distance of at least 2 m (6.5 ft) between the radar and HF radios (SSB).Other electronic devices and cables must be mounted more than 2 m (6.5 ft) from the radar beam path.GPS antennas must be positioned either above or below the radar beam path.

Yes, it is possible to install the GMR 18 xHD3 radar on the roof of a cabin or a hard top. However, it is recommended to use a raised mounting bracket or an appropriate structure to elevate the installation height. This helps prevent the roof from interfering with the radar signal, especially if the surface is metallic, and ensures the radar beam (which extends 12.5 degrees from the horizontal centerline) clears the roof edge.

To calculate the required mounting height on a roof or hardtop, use the following equation:

(Distance (mm) × 0.222) - 150 = height (mm)

Or in inches:

(Distance (in) × 0.222) - 6 = height (in)

The 'Distance' refers to the measurement from the planned mounting location to the farthest forward corner of a rectangular roof, or to the forward apex of a curved roof. Then install a riser or bracket so the radar base is equal to or greater than the calculated height.

For power wiring, it is recommended to connect the cable directly to the battery. Do not remove the inline fuse holder, as the appropriate fuse must be in place to prevent any risk of injury or damage to the product. If power cable extension is required, use the appropriate wire gauge based on the extension length to ensure sufficient power transmission:

2 m (6.5 ft): 16 AWG (1.31 mm²)4 m (13 ft): 14 AWG (2.08 mm²)6 m (19.5 ft): 12 AWG (3.31 mm²)

Yes, it is mandatory to update the software of your Garmin chartplotter when installing the GMR 18 xHD3 radome. For detailed instructions on updating the software, refer to your chartplotter's user manual.

The GMR 18 xHD3 radome uses Garmin BlueNet™ network technology and is compatible with Garmin BlueNet devices as well as Garmin Marine Network devices. For optimal performance and better support for future updates, it is recommended to connect it to the Garmin BlueNet side of your network whenever possible.

If your boat is equipped only with Garmin Marine Network devices, you will need to use a Garmin Marine Network adapter cable to connect the GMR 18 xHD3 radome to your network. The part number for this adapter cable is 010-12531-01 and it can be purchased separately if not included with the product.

Yes, to achieve the best possible performance and to avoid potential damage to the device or your vessel, installation by a qualified marine technician is strongly recommended.