How to support radar?

I just spent a while at Home Depot looking for "plastic plumbing parts" that might do what I need. Not sure how to put it all together yet, but still looking.

I am still wondering about using a post type, with a "plus sign (+)" cross section, with some forward rake, and obviously a base plate to match what has been there already, and the top plate to fit the RayMarine radome.

The reason for the plus sign as opposed to the standard type tube is to possibly increase the radar return from the flat surfaces. (Taken from the popular round or square 3 plane reflectors). I'm thinking this may help enhance my radar visibility.

I'd like to hear any thoughts on that possibility.

Harvey
SleepyC :moon
 
After a season of boating, including up and down a local river with locks and low bridges, I'm very glad I just mounted my radome on the roof. I'm also satisfied with the returns I paint. I do have a 3/4" spacer beneath the aft bolts, so as to give me a more level view pane when underway.
 
But, it is important for such a classic boat as a C-Dory, looks "cool." Therefore, a stainless radar arch or mount takes away the recycled milk bottle look to other mounts and of course you must have twin engines to complete the look :wink :wink
 
potter water":7lrdm5qx said:
But, it is important for such a classic boat as a C-Dory, looks "cool." Therefore, a stainless radar arch or mount takes away the recycled milk bottle look to other mounts and of course you must have twin engines to complete the look :wink :wink
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Harry,

You and I could get along. I do agree on the recycled look, (although it could be camouflaged reasonably) too, but more, I like the idea of the stainless.

What I am really trying to do is increase my radar return, and I'm thinking a flat surface (or the 90 degree angles formed by 2 intersecting vertical planes) would return more signal than the round surface of a vertical pipe. The problem is I need more vertical rise than what the SS version of the Scan Strut provides.

Harvey
SleepyC:moon

January_2010_346.thumb.jpg
 
hardee":xwgd165i said:
I am still wondering about using a post type, with a "plus sign (+)" cross section, with some forward rake, and obviously a base plate to match what has been there already, and the top plate to fit the RayMarine radome.

The reason for the plus sign as opposed to the standard type tube is to possibly increase the radar return from the flat surfaces. (Taken from the popular round or square 3 plane reflectors). I'm thinking this may help enhance my radar visibility.

I'd like to hear any thoughts on that possibility.

Harvey
SleepyC :moon
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You are postulating that flat surfaces might substitute for radar reflectors?
The classic radar reflector gives multi reflective surfaces, which will give a return at any angle. This is why the foil/alumium type of reflector is in the "Water Catch" position. Where there is most likely to be a return. A flat surface will give a minimal return, and only when it is at right angles to the radar beam which hits it. It might increase the radar return a minimal amount--if you want to be seen go with a redar reflector. Better yet, be proactive and stay out of the way of the big guys--as I know you already do.
 
Yes Bob, I am basing my thoughts on the return of the flat surface, PLUS adding the second flat surface, intersecting, (+), so I would have the 2 vertical planes like the round reflector, and agree I am missing the horizontal plane reflector and obviously the "catch rain" angulation, but I am increasing the flat surface reflectance. I realize that it may not be as effective as a regular radar reflector, but still think it might be better than a round surface.

I know maybe this is a reach, and it may make more sense ($$$ wise) to just add another "device" up on top of the boat but that is kind of what I am trying to avoid (looking like a collection of stuff on the cabin top)

Harvey
SleepyC:moon
 
Sleepy, as I think through your concern, I have to rely on my own experience with my raymarine radar. It picks up pretty small targets such as nav bouys several miles out. It also picks up small glass boats pretty easily at those ranges as well.

I'm thinking that in terms of radar for safety around other boats that you wont gain much without a pro-designed radar reflector by experimenting around with your radar support. Your checking your radar is going to be your safest use of radar as the big boats have a lot of radar cross section because of metal hulls or a lot of metal on a large fiberglass cruiser hull. Often, you will see them before they will see you, even with you having a pro-class radar reflector. Dory's just sit low in the water, and unless you can get a good purpose built radar reflector up significantly higher than your cabin top I don't think you will be helping yourself very much.

My opinion is that you support the radar in a way that pleases you and don't spend time trying to get a better cross section signature from the mount. A bunch of good reflective surfaces placed up a long way will serve you much better. If you have rocket launcher such that you can insert a pole and put a reflector up 10 feet or so will be much more effective in getting the other guy to see you.

Best solution is you watch the radar on occasion and keep your eyes out on the water. (That is of course unless you are fogbound, in which case, getting out a collapsible reflector and getting it up high is a good idea.)

I speak from a small amount of engineering experience having worked on stealth weapons design many years ago. I don't have that much expertise as a radar user in the fog in a big ship environment.
 
We had a Firdell Blipper Radar Reflector (which at the time was the best rated radar reflector available--there are some which seem to be slightly better now. )The reflector was about 40 feet up on the mizzen mast. The longest distance we were picked up by radar was by Bob Ballard's research vessel from Wood's Hole: R/V Knorr, and the distance was about 13 miles. We had picked the Knorr up at about 16 miles distant on our radar. This was in fairly calm weather (Tradewinds of 20 knots and swell of 4 to 5 feet) about 150 Miles East of Barbados. I had called the vessel at XX lat and XX Long, asking for a report on our radar visability. So the crew was looking for us (about 3AM)--the research vessel was running slowly fulling a side scan sonar fish. I have to assume that the R/V Knorr had some very sophisticated radar.
 
Thanks for the replies so far. At this point I am waiting for a bid from a fabrication shop on the custom plus sign (+) style and thinking about how it might work. If the cross section is + and then that is tilted froward at 25 or so degrees, I'm thinking that the radar signal would just be bounced back but at an elevated angle, so may not have any improved return at all.

The round support will give some return because at no matter what angle, there is a surface that reflects back to the sending source.

Note to Harry. I just don't really want to be a stealth C-dory :lol:
Note to Bob. Farthest that I know of being spotted on radar is about 3 miles. That is one of the reasons I am considering the active AIS.

I still need to get a support that will give me about 10 inches above the roof, so that it clears my hailer.

Thanks for all the good replies.

Harvey
SleepyC:moon
 
I also mounted the Garmin HD 18 this past spring and used the stainless 5" mount from battlewagonmounts.com. It is mounted on the aft end of the cabin for a couple reasons: 1) Garmin instructions advise that the radar unit not be placed any closer than 36" of any other electronics, 2) Wanted the forward end of cabin accessible foy the dingy. This mount also includes an LED anchor light aft of the radar which again leaves a clean roof for the dingy.

This mount allows the boat to fit under our 10ft height garage door which was another factor. If not for garage storage, I think I would have preferred the arch because the radar view could look over the dingy. I experimented with the radar view looking forward through the dingy, compared to a clear view. The view is degraded somewhat, but still very capable. I guess everything is a compromise. "a houseboat is not a particularly good boat and not a good house".
 
I guess everything is a compromise. "a houseboat is not a particularly good boat and not a good house".

Maybe, but it is a site bit better boat than a house :wink: :lol:

I'm surprised that the dingy has any effect on you radar image.

Harvey
SleepyC
 
hardee":jwl7y46a said:
I'm surprised that the dingy has any effect on you radar image.
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I made a similar comment when Local Boy mentioned getting an arch to get the radar up over the dinghy - because I was pretty sure radar would shoot right through rubber or wood. But if I remember correctly, he explained that his particular dinghy has a metal transom, and it was just in the right place to interfere.
 
Yep, our dingy also has an aluminum transom plate. I experimented by removing it and the radar capability seemed to improve. I did the experimenting by approaching a metal buoy head on. It was hard to tell any difference at first until I turned the gain up. That is when the shadowing was apparent.

Now that I know what's going on, I am comfortable with it's capability, even with the metal transom plate on the dingy. We are still rookies, but the combination of the Garmin HD 18, 740S Chartplotter with AIS overlay from the radio defineately increases situational awareness and reduces risk, making any trip more enjoyable.
 
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