How to support radar?

P

Plan C

New member
I bought a Garmin 18HT and would like to hear what the best choices are for mounting it on a 22 Cruiser. Unless someone has a great buy on a used arch, I think I just want to put it above the front of the cabin.

What to do?

Also, what is desireable angle from the cabin top?

Dave
 
hi dave,
a great buy has many meanings. i had "the railmakers northwest", www.railmakersnw.com 425-259-9236, build me a ss radar arch which i thought was a great buy. they included a custom mount for the masthead light and the fit was perfect. improved both the value and look of my boat. i asked them to provide a larger mounting area for the radar dome, gps antenna and air horns, all of which turned out perfect, as well.
pat
 
Plan C":qf4y2nss said:
I bought a Garmin 18HT and would like to hear what the best choices are for mounting it on a 22 Cruiser. Unless someone has a great buy on a used arch, I think I just want to put it above the front of the cabin.

What to do?

Also, what is desireable angle from the cabin top?

Dave
Click to expand...

Hi Dave,
You will find there is debate about radar angle. Radar's have a 20-23 degree angle of view depending upon the brand. When I approach a 75' high bridge for example my radar shows a wall almost until I go under it which would seem to indicate even more than the published view angle. A few degrees of angle will not likely make any difference.

With that being said, I mounted my radome on a 2 degree wedge to have my center of radar view as close to level as possible when underway. Obviously your angle of attack will vary with loads, power setting, weather, etc. but clearly a boat moves through the water at an angle at anything other than displacement speed.

Radar height is your friend and is usually the range limiting factor on small vessels. To see your range check out the 'Radar Range Calculator' link here:

http://www.commercialcaptains.com/additional_resources

If your radar is 8' off the water your max range to paint a 20' tall vessel would be 10.33 miles for example. If your radar was mounted 9' off the water your max range to paint a 20' tall vessel would be 10.57 miles.

I also like the idea of lifting the radar source farther away from occupants and providing space for a radar reflector. I installed a 10" Sea View radar mount. I mounted my trilens radar reflector directly on the hard top. You would not want highly reflective things mounted close to your radar.

--Matt
 
My 18 inch Raymarine dome is mounted directly to the cabin top as far forward as possible. This works fine for me and keeps the overall height of the boat lower for storage purposes.
 
>As much as the things cost, you would think it could support itself

Laughed out loud!

I didn't consider mounting on the roof as an option. RETREIVER... Did you make a mounting block or something to put under it, or just bolt it to the roof?

I am not concerned about maximum range, and I want to keep my overall height and center of gravity down.

As to angle - since I wrote today, I spoke to Les at EQ Harbor Services. I asked him about it, and he reminded me that in deep fog you are probably not planing. When you are planing, your bow is elevated. You cannot have a perfect angle aim, and he says the angle that the device covers will work well enough for each if it is mounted flat. He said that is how they have done it. That is enough for me.

Dave
 
Plan C":37ge2xoz said:
... Les at EQ...He said...enough for me.
Click to expand...

As Pat Anderson is fond of saying: QED.

I think you'll find you keep the radar set on a low enough range that elevation and angle won't make any difference. Out of the 24 mile range the specs say my Garmin unit has, I rarely use more than the first two. If I ever find myself in a spot where I need to see the whole 24 miles around me, I think I'll be worried about a lot of other things.

Mine is sitting on a pedestal about a foot above the roof, but that is only because the previous owner glued the pedestal down with 5200 and I didn't want to tear up the glass by taking it off when I put my big Garmin dome up there. I would have preferred to mount the dome lower.

Sorry about the support itself joke. I have been too serious for too long.
 
Did you shorten wires or just leave them coiled? My boat is already feeling like a wire storage warehouse. I see there is a provision for shortening the data wiring. Shortening the electric wires is simple.

Dave
 
I didn't do the installation (Master Marine did) but I'm pretty sure the excess wire is coiled up. My recollection is that the 2kW Raymarine units have power and data on the same cable and the extra is just coiled up behind the helm.
 
Dave,
Mounted my 18HT on 1"vinyl stringers right on the cabin top. The stringers were shaped to fit the slight radius of the cabin top. There has not been an instance where an object was out of view due to the angle. Pics of the mount are in the album.
Mike "Levity"
 
I have mounted about half a dozen radars on my "Commode mount"--using 4" heavy duty white PVC pipe and two WC fittings from Home Depot. Make the radar base out of high density cutting board, (Walmart: $6) or Starboard. Inside of the cabin, I use large fender washers about 1.5" diameter. Total cost about $20, and I make the mounts about a foot high. No wedge, since I am usually going at slow speed in really limited visability.

As for what range you want: Most folks run radar at 1 to 3 miles. We have many thousands of hours running under radar. We keep the radar at 3 miles, run out to 6 and 12 or even 24 miles about every 15 minutes when crossing oceans or open water. However in crowded conditions I want to know what is close to me, not what is 20 miles away (all you will see is land masses there).

IMG_0558.sized.jpg
 
Thanks for the details, Bob. If I change my mind and want to raise it, that looks like an excellent solution. What do you consider the advantages of raising the unit by a foot? Why do that instead of just a roof mount?

Dave
 
The reason that I raise the radar a foot, is that the beam then clears the air conditioner, the loud hailer (on the Tom Cat) as well as the dinghy transom, and less likely that the passenger will be in the beam if standing in the cockpit. In reality it does not make a lot of difference, if you don't have an AC or carry the dinghy which might have some metal in the transom on the roof).

This whole idea started when friend on Trawler List wanted to go to our local scrap yard to find metal for a mount for his radar. We could not find the exact pieces we wanted, so I suggested why not try the PVC mount. He has had it in full time use for over 8 years, with no problems, and I believe done the loop twice.
 
Just saw this thread, from referral in another thread. Very cool radar mount Bob. Kind of glad I didn't see it earlier because I probably would have made one. However I have been very pleased with my radars operation mounted directly on the roof as you alluded to in your comments. Especially nice not to have the higher clearance to worry about. But definitely something I would consider if I wanted to raise it. Colby
 
Hi Dave,

I was just going to say call me, (and yo can do that too) but for our purposes around this area I will tell what I use and why.

If I am crossing the straits, I want to see what conflicting traffic is out there and be able to judge accordingly so I will usually run a page on the plotter that has chart, AIS and radar overlay all set so chart is 24 miles and radar 12 miles (provides full coverage on the chart.) That will catch shipping traffic and Victoria Clippers.

If I am not crossing the shipping lanes, but going around the corner over your way, the setting would probably be at 6 miles, so I have 3 miles on either side and 3 out front. (I run the radar centered on the boat, not shifted back to 1/3 position so that I have equal warning from behind as well as in front.) There are times that I will bring it in to 3 mile radar if I'm moving pretty slow and/or there is a lot of traffic in low vis or close conditions.

Hope that helps.

Harvey
SleepyC:moon
 
We have a post style mount, as opposed to an arch.

It reduces my overall height, allowing us to pass under lower bridges and such, and also weighs less, keeping the center of gravity down. On the other hand, this limits our dinghy size, as an arch could allow a longer dinghy to slide under it.

Either way, remember that radar uses brief, but high power microwave radiation, so you won't want to be walking around inside the "cone" while it is on.
 
If you havent purchased one yet, I have an unused radar tower. I purchased 2, not knowing which would provide the proper clearance and angle over my existing rocket launchers. I believe i paid $220 for it, but would let it go for something less than what I paid.

It has never been used and I believe the brand is scan strut.

I will dig it out of the storage in the morning and look up my record of what I paid. Photo will be up tomorrow as well.
 
Back
Top