Gimballed Radar Mounts

[npf1]

With a standard mast mount and a 2Kw radar (approx 6 years old), approx how much radar range is lost by, say, 25 degress of heel? Does anybody know if gimballed radar mounts are a good idea on a sailing boat? Or do they 'solve' a non-existant problem?
Thx

<hr width=100% size=1>

 

[Talbot]

most radars have a vertical beamwidth of abt 30 degrees so should not be a problem up to 15 degrees. will you really be using your radar when hard on the wind?

<hr width=100% size=1>

 

[npf1]

Thx. Might be doing an W-E transat next year. If we take the 'northern route', I've read that where the Labroador current meets the Gulf Stream, getting fog and wind simultaneously is quite common. Maybe just have to reduce the heel!

<hr width=100% size=1>

 

[malcp]

Typically the vertical beamwidth of your radar would be about 25degrees, so /-12.5 degrees above/below the horizon, and this means the radiated power from the scanner at this angle is 3dB down on the boresight power, ie the half power point. This means that the transmitter power 12.5 degrees off the horizontal would be 1kW. If my calculations serve me correctly this would correspond to a 30% loss in theoretical range, ie you could get about 70% of your non-heeled range. Perhaps a radio engineer could confirm. These figures are theoretical and I would guess the maximum non-heeled range for a 2kW radar is about 24nm and the 12.5 degree heeled range would be 70% of this (~17nm). This, of course, is not achievable in practice due to the curvature of the earth.

Bearing in mind the non-heeled usable range is likely to be 6-12nm (depending on antenna/target heights) the difference when heeled 12.5deg may not be noticeable. But at 25 deg heel I strongly suspect you will see a degradation. Perhaps someone with non-gimballed radar who has tried this can comment.

Another thing to bear in mind is the sensitivity of the radar to small targets. You are less likely to detect small targets when heeled.


<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by malcp on 04/11/2004 14:04 (server time).</FONT></P>

 

[bruce]

gimballed mounts are designed for sailboats because of heel, biggest problem is not enough coax to allow swing on mast causing coax failure due to excessive flexing at point where cable leaves mast, just leave enough to be sure of no strain at that point or at antenna.

<hr width=100% size=1>