Some days as a boat owner are certainly better than others. I had an issue with the cooling system on one of my Mercury Verado engines that required a repair on land. I pulled the boat out onto my trailer for a very short ride back to my house. On the way, construction forced me to reroute through some local tree-lined streets. When I arrived home, my 8-year old Raymarine radome was smashed beyond repair.
Choosing the Garmin GMR 18 HD
Since the boat already had a Garmin 1040xs plotter, I took that as an opportunity to go with a new radar for that unit rather than replace the Raymarine. Since the boat is only 28ft in length, a typical center console, and mostly used inshore, I chose the Garmin GMR 18 xHD. The 24 inch model would certainly provide better long range resolution, but the overall height of the boat means that the curvature of the earth makes that useless. If the boat was taller, then I would have considered the 24 inch model.
Unboxing
The contents were pretty basic; the dome, a set of studs, power cable, a mounting template, grommet, and the notorious Garmin rj45 cross-over network cable (more on that in the cabling section below).
Mounting
Fortunately for me, the mounting pattern was identical to the prior unit and the existing radar bracket was fine. I decided not to use the mounting studs and instead used four 1 1/4 inch M8 bolts. It just makes for a cleaner install with the bolt heads below the bracket instead of the nuts.
Cabling
Old radar cables were certainly tough to install because of their size and lack of flex. I thought it would be easier with the two distinct cables (network and power). I ran into a problem immediately because the rj45 network cable has an end that requires at least a 1 ¼ hole. That simply wasn’t going to work on my T-top and after an hour or so a struggling, I simply cut the end. I removed the inline fuse from the power cable because I connecting to an existing fuse panel (paying attention to the fuse size). Once I had run both the cables I was ready to deal with the network cable end. The Garmin network cable is a cross-over cable that allows devices to talk directly to each other. I purchased a pass-through network cable crimper and after a couple of practice ends, I was an expert. I disassembled the old connector and carefully copied the wire pattern. I even re-used the old connector housing. The entire process took less than an hour. Garmin sells a kit just for this, but I am not convinced you need it.
Damn, I Need a Hub
My next realization was that the plotter only has a single network cable input that was already in use by the Garmin sonar unit. Garmin makes a powered network hub (GMS 10) that allows you to connect up to 5 devices together. The installation was very easy and it worked exactly as expected.
Power Considerations
I was concerned about the direct power connections for both the radar and the hub. That concern was unfounded when I found that the network hub does power up until the plotter does. The radar unit does not power up until it is needed for transmission. There is really no need to add another master cutoff power switch (as other have suggested).
Performance
Wow! The old unit did not have the radar overly feature. The radar overlay with the Garmin GMR 18 xHD was incredible. I cannot image using the unit inshore without it. Finding flocks of birds is tricky with any unit, but it only took me less than an hour to manually tune this one. The larger radar units actually include a “bird mode” preset.
Frequently Asked Questions
The author chose the Garmin GMR 18 xHD because their boat is a 28ft center console primarily used for inshore fishing, and the 18 inch dome size balanced performance with the boat's height limitations. The 24 inch model was considered but dismissed due to the curvature of the earth limiting its range advantage on a lower-profile vessel.
The author found the Garmin RJ45 network cable's connector bulky, requiring a hole larger than what their T-top allowed. To solve this, they cut the connector end and re-terminated the cable using a pass-through network cable crimper, reusing the old connector housing to create a custom fit. They also removed the inline fuse from the power cable since they connected it to an existing fuse panel.
The Garmin GMS 10 powered network hub allows multiple Garmin devices, such as the radar and sonar units, to connect to a single network port on the plotter. Since the plotter has only one network input which was already occupied, the hub enables up to five devices to be networked together easily and reliably.
No, the author found no need for an additional master power cut-off switch because the network hub only powers up when the plotter is on, and the radar itself only powers on when transmitting. This self-regulating behavior simplifies power management on the boat.
The radar overlay on the Garmin GMR 18 xHD significantly enhanced the author's inshore navigation by integrating radar returns onto the chartplotter screen. This feature made it easier to identify objects and locate flocks of birds, which is particularly beneficial for fishing. The author tuned the radar manually in under an hour and appreciated the improved situational awareness.
The box contained the radar dome, a set of mounting studs, power cable, a mounting template, a grommet, and the notable Garmin RJ45 crossover network cable. These components provide everything needed for installation except additional networking accessories.
