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
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.
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.