Radar Placement

[Espiritu Buho]

I have a Tayana 48 and the radar went out. I learned ALL about how radar and other wiring gets zip tied and secured in conduit such that it can virtually never be removed and also presents problems installing new wires, such as those on my new B & G radar. I am thinking about skipping the hassle and mounting the radar on a deck mount at the stern but would welcome any and all input on this. My preferred location is on the mast but it seems impossible to remove and replace, plus secure the wires (to avoid slapping in the mast). Thoughts?

[Marathon1150]

I went back and forth on this for a year before choosing to install the radar antenna on the mast rather than something on the rear of the boat. The first time we had to take the mast down to work on it, I very much regretted the decision. There is a school of thought that there should be no connectors between the antenna and the radar set in the cockpit or cabin or whatever. The cable for a Furuno radar built in the mid-2000's has an incredible number of wires that had to be cut and then soldered back together. I've done this twice now.

If I had the choice again, I would put the radar antenna on a post in a gimbal on the stern. High enough so that there is no risk that anybody's head would intercept the radar beam when it is operating.

I suspect that there is a formula for the detail and range lost because of the lower mounting height but the signal loss even through soldered joints is probably significant as well. I'm not an expert or even a well informed amateur so maybe another response will provide an argument for putting the antenna on the mast.

[Espiritu Buho]

Thanks for that good information! I am anxious to hear what everyone's thoughts are on it. Eventually I plan to put a nice arch aft for solar panels, so the radar could eventually be moved there. I continue to be baffled at how many things are installed during production with no regard for the long-term challenges of repair, replacement or upgrade.

[Donnybrook]

My previous radar was mast mounted. My next one will be on a stern tower. I had wiring issues while stepping mast (stepped every winter at the time). This was a Furuno 1621. Newer radars may be easier to splice.

Other considerations are gimballing while heeled and having too high a mount resulting in missed short range targets. I'd me more concerned about missing a target 100 feet in front than 20 miles away. I don't have personal experience with a tower mounted radar so I'm interested in others experience, too.

[Adelie]

Don Dodds in "Modern Seamanship" has a good analysis that says it should be at least 12' above this highest standing level (coach roof) on the boat for safety.
And 16-32' above the water is about right range. Higher has little affect on the range at which even ships can be seen.

[Jammer]

Originally Posted by Marathon1150

I went back and forth on this for a year before choosing to install the radar antenna on the mast rather than something on the rear of the boat. The first time we had to take the mast down to work on it, I very much regretted the decision. There is a school of thought that there should be no connectors between the antenna and the radar set in the cockpit or cabin or whatever. The cable for a Furuno radar built in the mid-2000's has an incredible number of wires that had to be cut and then soldered back together. I've done this twice now.

I think that's crazy. There are all kinds of connectors that are reliable in a marine environment.


Modern radars use ordinary cat 5 twisted pair. 8 wires, probably only half in actual use. The M12 x-code ones are the best I've seen but there are cheaper choices. https://www.mcmaster.com/m12-coded-c...12-connectors/


The Hartig push-pull RJ45s are also good, and are a little cheaper at least in quantity. We use them at work: https://b2b.harting.com/ebusiness/en...se&search=true

[Adelie]

Originally Posted by Jammer

I think that's crazy. There are all kinds of connectors that are reliable in a marine environment.


Modern radars use ordinary cat 5 twisted pair. 8 wires, probably only half in actual use. The M12 x-code ones are the best I've seen but there are cheaper choices. https://www.mcmaster.com/m12-coded-c...12-connectors/


The Hartig push-pull RJ45s are also good, and are a little cheaper at least in quantity. We use them at work: https://b2b.harting.com/ebusiness/en...se&search=true

Remember, radar cabling pushes a lot of power to the dome, both to spin the antenna and kW of power for the outbound signal so some of the wires need to be substantial.

[Discovery 15797]

Originally Posted by Adelie

Remember, radar cabling pushes a lot of power to the dome, both to spin the antenna and kW of power for the outbound signal so some of the wires need to be substantial.

The transmitter and initial signal processing unit is in the antenna unit. You aren't pushing kilowatts of power through wires.

[Adelie]

Originally Posted by Discovery 15797

The transmitter and initial signal processing unit is in the antenna unit. You aren't pushing kilowatts of power through wires.

OK I was imprecise. The antenna transmits at kW which is pulsed but still involves significant energy as well as spinning the antenna. Looking up Furuno data it looks like 3.5A continuous. Not that much if it were intermittent, but significant as it is continuous and at the other end of a 10m cable.