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Mounting Radar on the Mast vs pole


1paulg

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If a Radar is mounted on a reasonable support at the back of the boat is the performance likely to be inferior to having a mast mount...obviously the mast mount will be higher so presumably better signal..? but also higher windage... any thoughts..

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Yes it causes windage and you have weight aloft as well. But it allows you to get the best "view". The radar has a down angle. I may be wrong, but i think it is 21deg down angle. Your handbook should tell you. So you don't want to be too high up the mast. Fix it at a height to allow you to get a good view over the bow. That can allow you to pick up a mooring in the dark. In saying that though, many have their scanners mounted to poles and it works OK. But you will never pick up a mooring on the bow as a target.

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Yes it causes windage and you have weight aloft as well. But it allows you to get the best "view". The radar has a down angle. I may be wrong, but i think it is 21deg down angle. Your handbook should tell you. So you don't want to be too high up the mast. Fix it at a height to allow you to get a good view over the bow. That can allow you to pick up a mooring in the dark. In saying that though, many have their scanners mounted to poles and it works OK. But you will never pick up a mooring on the bow as a target.

 

Different scanners may have different verticle beam widths - check the manuals.

If you have a verticle beam with of 21deg (+/-10.5deg on vertical plane) and the scanner is mounted 10m above sea level you should have a blind sector will extend a little less than 54metres around the scanner at sea level. Some radars have an accuracy of +/-15m at the lowest range scale - check the manual as they will state the accuracy for diffferent ranges.

 

Some mooring buoys will not show up on radar due to what they are made of and or their shape. A 20tonne steel buoy with an unusual shape would not show until we were almost on top of it from down tide yet from up tide it painted well on the screen.

 

One plus of mast mounting is that you avoid the interference cause by the mast being ahead of the scanner (ie the direction you are going). http://Do notmount the scanner at the same height as spreaders or other horizontal ftting or you may end up with large blind sectors or backscatter that results in you winding up the sea clutter control and or reducing the gain and end up missing targets.

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I chose to go with mast mounted much in line with what rigger has said. It is a balance of height versus rolling motion. Mounting the radar on the very top of the mast will give you the greatest range but the roll motion is too much for close quaters use. The best compromise seems to be around the first spreaders. This allows enough height to make reasonable use of the radar units range.

Its also above and forwards of peoples heads.....(I have seen stern mounted radar units that are almost directly in line with a helmsmans head).

 

The back stay mounted gimballed units are interesting , but I would rather not have the weight on the rigging, and also wonder whether it makes that much differance.

 

In close quarters, radar over chart plotter is a wonderful thing....

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Hi AA

Gimbled mounts for masts also exist.

 

I have seen the commercial versions of these and thought about making my mast mount gimbaled, but wondered how the cables would stand up in the long run to what would be thousands and thousands of flexes over time.

...any thoughts ?

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Of course with a cat you don't need to gimbal the antenna. :D

One issue with most yacht radars is the performance is limited by the diameter of the antenna.

The open array type you see on commercial boats, trawlers etc are miles better in any seaway.

I understand that the broadband type largely fixes this but have never tried one

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