In article ,
Larry wrote:

....
Radar cannot see further than the horizon.
The horizon depends on how far UP the antenna is mounted.

I know - MSEE and lots of experience in this band in military service.

I am more interested in the mechanics of SR arches than electronics.

From your SR31, we're up just above the flybridge. How far can YOU
see
with binoculars...6 miles? 5? Check it out.

If we had a 500KW military surface search radar on your arch, it could
"see" targets 6 miles away....maybe 8 or 9 if they are TALL targets like
lighthouses, radio towers, etc. So, what's the point?

In a word: Resolution. A radome antenna has 4 to 6 degrees horizontal
beam width, a 4' slot antenna less has 1.8 degrees. Makes all the
difference in tight places like rivers. Like seeing one or two ships. Or
a small ship or sea clutter.
I would go as far as saying that horizontal resolution is the only
specification to worry about. What has not been captured by the antenna
is never going to show up on the display.

You're not as tall as a containership, who can use a more powerful radar.
So, why waste money on HIS radar transceiver??

From up there, how about the 4KW radome? Loading on both the arch and
your electrical system are lots less, also your wallet. 4KW has no
trouble making a target at 8 miles.

I AM talking about 4 kW, no more. What did you expect?

....
I know the big swinging radar horn impresses the other sailors and looks
cool like you're an aircraft carrier....but why?....(c;

I have no TV antenna, a 6" VHF antenna only, and no satellite dish
compensated for the movements ... sorry, no need to impress. I'd rather
be sailing anyway but it is not possible.


Besides, you're not going 400 knots like a jet. If you can see targets 2
miles away you have MINUTES to turn away...not seconds. That's far
enough for collision avoidance isn't it?

As I said above: It's all about resolution. Like seeing a small boat
without lights when going 25 knots in darkness.

Do you know what the actual permissible mechanical load would be on my
arch?

TIA

Marc

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