Radar Installation

[willie]

http://www.pc-land.com/simplelife/simple_life_dbase/forums/thread-view.asp?tid=21&posts=1#M45

I wanted to install a radar, but not on the mast and not on the back-stay, so that really only left me one choice, a pole.
So I looked long and hard for a good radar pole and could not find one that made sense. A radar pole is essentially a huge lever attached to the back of your boat and all but one I found would eventually destroy it self at the points it attaches to the boat. Yacht Specialties hand made the radar pole I choose, I could not be happier.

The pole attaches to a base that moves forward and aft, port and starboard. In other words it swivels in all directions so it is not possible to apply a lateral force to the pole mount.

The stanchions are a terrible place to mount anything too, so two struts were used with ball joints to support the pole laterally.

The pole can be ordered up to 10 feet.

I was confused only about one thing. Why did people mount their radars way up on their masts 30 and 40 feet above the water line. I wanted to use MARPA and collision detection so I needed to do some math and figure out the best height to mount a radar, that is unless I wanted to do weather forecasting.. Hee...Hee.

R2 = rä2 + (rä + H)2 - 2rä(rä + H) · cos α

Here is a link to my excel spread sheet I calculated based on the curvature of the earth: http://www.pc-land.com/simplelife/Radar2.htm

Heres one at zero object height that is easier to understand and figure with: http://www.pc-land.com/simplelife/Radar3.htm

Heres one with an object height of 10 feet and a radar height of 30 feet: http://www.pc-land.com/simplelife/Radar4.htm

The problem with the radar at 30 feet is the huge blind spot around your boat.

You will see that a radar height of 11.5 feet off the water and an object height of 10 feet off the water the radar range based on the earths curvature is 8.03 miles and an object height of 0 feet the range is 4.88 miles at a radar height of 16 feet.

The radar transmits its radio waves at 12 degrees angle above and below the center-line of the radar and so at 11.5 feet the radar just missed the bow of my boat. Perfect! and still has good range.

[Joe Kern]

Great looking set-up and the pictures were very helpful in understanding your set-up.  I am looking forward to comments (criticisms) from the various experts on the thread, but will defintilty consider your approach when I bite the bullet and go with radar.

Joe