Hello, I have a autohelm 50 radar unit on my 1992 Catalina 36 which is mounted on the mast about 3 feet above the spreader. It seems to read OK at long distances but not so good at close range. Should I move it below the spreader or put a shim under it to pan lower?  (what abouts the old holes?) I have the mast off the boat for the winter, so now is the time to do it. I just bought the boat and sailed it from Lake Michigan to Lake Superior (Apostle Islands) last summer.     Any input helpful, thank you, Dave

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You may have to choose in what range you want to optimize the radar. If above 6 miles range, keep it where it is in the mast, if you are more interested in the area below 3 miles, move it to a stern pole and put in a cradle. I have mine at the stern on my SO37, and works like a wonder in the closest range. Even used it for anchoring at night in crowded anchorages to get exact distances to other boats. However above 6 miles, not that good. When tracking squalls and bad weather at max range it is excellent. Do a rough calculation with beam-with, mounting height, and you may see how far from the boat the beam 'hits' the water. But as you mentioned, you may correct it by putting a wedge under the antenna and direct it down. Even mast rake may come into play.

Hello Dave,

 I'm afraid I don't have much information to offer up on the AH ST50 Plus radar system as it has been discontinued and de-supported many years ago. I did come across a manual that I have posted to this thread. 

 Thx, to Morton for offering up his valuable insight.


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