Of course I have a radar reflector mounted high in the rigging on my Hunter 340, but I'm wondering if the stainless steel arch also acts as a radar reflector (?) Thanks, Ken Kindrick
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Firing up the masses!
Ken, All modern radar's will see your boat without your boat having a reflector. It is an urban myth that fiberglass boats need a reflector. My radar was new in 1991. It's a Raytheon R20x. It sees DUCKS sitting on the water. It also sees powerboat wakes on calm water. Older units I've seen do the same job. The key seems to be 'raster scan' and the laws of physics. I'll cut and paste a reply I wrote last month on this subject. Here ya go; In my opinion,,, I love our R20X by Raytheon (JRC) It is a 24Mi with the enclosed dome. We bought it in '91 and have used it as our primary form of navigation from Brownsville Washington to Trinidad and back. The antenna is mounted on a radar arch on our Hunter 34, Epitome'. Our unit is jumperd on the motherboard so that it displays the 32 mile range ring. It has the same display and power as the 32 mile model but without the open array antenna. Here is how we use the longer range. We set the range at 12 miles, then use the offset feature to our stern as far aft as it will move us. After the unit displays in offset mode we can increase the range to 24mi and low and behold, we can see ahead to 39.999999mi. That forty mile range is great for finding headlands when off shore or looking for the next 'bend in the road'. That range would not be available if we didn't jumper the motherboard to 32mi. The laws of physics apply with radar so there is little that we sailors can do with these things except select one to work with our personal style. Here is some other stuff I've learned. More important than power or range for close in viewing is 'Horizontal Beam Width'. The lower the number, the better the resolution. Our radar has a HBW of 2.2 degrees. That is much less than those lower powered units with smaller radomes. What that does for us is it lets us see the difference between a tug and a tow. Important in Puget Sound. We also find ourselves dodging DUCKs so factor that in too. And we can see the wake of ski boats and airplanes at low altitude. (as long as they aren't stealth). After a lightning strike off the coast of Panama (us too), our unit was in the shop for repairs. I had taken it to the States for repair but had to buy a Sitex with the same size dome but only 2kw of power. The first thing I noticed was that the buoys marking the channel to the Balboa entrance of the Panama Canal melded into one target before running out of buoys! That was scary enough but what really freaked me out was what we saw, or didn't see the next week in the Caribbean. We were sailing off shore past Isla Provedencia with no intention of visiting. It was a clear afternoon. We were looking at it. GPS said we were 17 miles from the near shore. It is 1700 Feet tall. The radar NEVER SAW IT on 24 mile range, or any range. I called the manufacturer when we reached the states and they had NO solution. The tuner was automatic so it's lack of performance could only be attributed to lack of power. We sold it and took a loss. Fortunately Raytheon was able to affect repair at a reasonable cost. A couple of years later, a idiotic navigational error by the skipper, (me) had us forty miles, or more on the wrong side of Grenada from Trinidad. I had used the wrong compass course for over 12 hours. The GPS was down because of a software defect. They were too expensive to carry a backup then. Besides, who needs GPS in the eastern Caribbean, right? Well at that point, all we had was dead reckoning and Radar. Our DR position plot was also based on a guess of 8 1/2 knots speed and a two knot favorable current. I say 'guess' because our knotmeter was down too. We plotted a course for Granada at sunset. (a friend was with me and we were suppose to pick up my wife at the airport the next afternoon) Of course the island was suppose to be now dead to windward (and 'currentward') We powered up! At 0400 local time, the airport of Grenada appeared at 33mi using the offset feature DIRECTLY OFF THE BOW!. The altitude of that airport is only about 20 feet but there it was! Never, have I felt such a sense of relief. You see, I don't study those dead reckoning 'how to' articles. We might have found the island without radar but I wouldn't have wanted to find out. We drove right in to Prickly Bay and met the flight. When my wife stepped out of Customs I acted like I had been hanging out and waiting for a week, HaH! Sure glad I got rid of that Sitex! Some other things to consider, the US Navy's primary means of navigation is radar. Since Pearl Harbor, no active Navy ship, anywhere, by regulation, is allowed to turn OFF its' radar. Also radar is not DR or even GPS. Those methods place your position in a 'cocked hat'. Your observed position on the radar screen is EXACTLY where you are! OK, these are just my personal experiences and opinions. I COULD BE WRONG! Fred Ficarra
Ken, All modern radar's will see your boat without your boat having a reflector. It is an urban myth that fiberglass boats need a reflector. My radar was new in 1991. It's a Raytheon R20x. It sees DUCKS sitting on the water. It also sees powerboat wakes on calm water. Older units I've seen do the same job. The key seems to be 'raster scan' and the laws of physics. I'll cut and paste a reply I wrote last month on this subject. Here ya go; In my opinion,,, I love our R20X by Raytheon (JRC) It is a 24Mi with the enclosed dome. We bought it in '91 and have used it as our primary form of navigation from Brownsville Washington to Trinidad and back. The antenna is mounted on a radar arch on our Hunter 34, Epitome'. Our unit is jumperd on the motherboard so that it displays the 32 mile range ring. It has the same display and power as the 32 mile model but without the open array antenna. Here is how we use the longer range. We set the range at 12 miles, then use the offset feature to our stern as far aft as it will move us. After the unit displays in offset mode we can increase the range to 24mi and low and behold, we can see ahead to 39.999999mi. That forty mile range is great for finding headlands when off shore or looking for the next 'bend in the road'. That range would not be available if we didn't jumper the motherboard to 32mi. The laws of physics apply with radar so there is little that we sailors can do with these things except select one to work with our personal style. Here is some other stuff I've learned. More important than power or range for close in viewing is 'Horizontal Beam Width'. The lower the number, the better the resolution. Our radar has a HBW of 2.2 degrees. That is much less than those lower powered units with smaller radomes. What that does for us is it lets us see the difference between a tug and a tow. Important in Puget Sound. We also find ourselves dodging DUCKs so factor that in too. And we can see the wake of ski boats and airplanes at low altitude. (as long as they aren't stealth). After a lightning strike off the coast of Panama (us too), our unit was in the shop for repairs. I had taken it to the States for repair but had to buy a Sitex with the same size dome but only 2kw of power. The first thing I noticed was that the buoys marking the channel to the Balboa entrance of the Panama Canal melded into one target before running out of buoys! That was scary enough but what really freaked me out was what we saw, or didn't see the next week in the Caribbean. We were sailing off shore past Isla Provedencia with no intention of visiting. It was a clear afternoon. We were looking at it. GPS said we were 17 miles from the near shore. It is 1700 Feet tall. The radar NEVER SAW IT on 24 mile range, or any range. I called the manufacturer when we reached the states and they had NO solution. The tuner was automatic so it's lack of performance could only be attributed to lack of power. We sold it and took a loss. Fortunately Raytheon was able to affect repair at a reasonable cost. A couple of years later, a idiotic navigational error by the skipper, (me) had us forty miles, or more on the wrong side of Grenada from Trinidad. I had used the wrong compass course for over 12 hours. The GPS was down because of a software defect. They were too expensive to carry a backup then. Besides, who needs GPS in the eastern Caribbean, right? Well at that point, all we had was dead reckoning and Radar. Our DR position plot was also based on a guess of 8 1/2 knots speed and a two knot favorable current. I say 'guess' because our knotmeter was down too. We plotted a course for Granada at sunset. (a friend was with me and we were suppose to pick up my wife at the airport the next afternoon) Of course the island was suppose to be now dead to windward (and 'currentward') We powered up! At 0400 local time, the airport of Grenada appeared at 33mi using the offset feature DIRECTLY OFF THE BOW!. The altitude of that airport is only about 20 feet but there it was! Never, have I felt such a sense of relief. You see, I don't study those dead reckoning 'how to' articles. We might have found the island without radar but I wouldn't have wanted to find out. We drove right in to Prickly Bay and met the flight. When my wife stepped out of Customs I acted like I had been hanging out and waiting for a week, HaH! Sure glad I got rid of that Sitex! Some other things to consider, the US Navy's primary means of navigation is radar. Since Pearl Harbor, no active Navy ship, anywhere, by regulation, is allowed to turn OFF its' radar. Also radar is not DR or even GPS. Those methods place your position in a 'cocked hat'. Your observed position on the radar screen is EXACTLY where you are! OK, these are just my personal experiences and opinions. I COULD BE WRONG! Fred Ficarra
Yes and...
Any metal object will act as a reflector so yes the arch will reflect, but how will is subject to testing. A radar reflector is designed to maximize reflections by including 90 degree angles. This will be more effective then the smooth curves on an arch or for that matter any other metal part of your boat. If your concerned with being highly visible by other radars, the reflector should stay.
Any metal object will act as a reflector so yes the arch will reflect, but how will is subject to testing. A radar reflector is designed to maximize reflections by including 90 degree angles. This will be more effective then the smooth curves on an arch or for that matter any other metal part of your boat. If your concerned with being highly visible by other radars, the reflector should stay.
The masses respond
Fred writes of seeing ducks on the water, but doing so is only going to be possible on flat, calm water. Put Fred's boat out in a twelve foot swell with six foot chop and I gaurantee he won't be seeing ducks. Nor will he be seeing the blips from your stainless arch when you're down in the swell. A proper radar reflector does two things: (1) it increases the apparent size of your boat's radar signiture, and (2) it adds height to the signiture so that when there are swells between you and the sending boat, you can still be seen. In other words, the purpose of the radar reflector is so that you won't appear to be just another sitting duck.
Fred writes of seeing ducks on the water, but doing so is only going to be possible on flat, calm water. Put Fred's boat out in a twelve foot swell with six foot chop and I gaurantee he won't be seeing ducks. Nor will he be seeing the blips from your stainless arch when you're down in the swell. A proper radar reflector does two things: (1) it increases the apparent size of your boat's radar signiture, and (2) it adds height to the signiture so that when there are swells between you and the sending boat, you can still be seen. In other words, the purpose of the radar reflector is so that you won't appear to be just another sitting duck.
Round Surfaces Make Lousy Reflectors
Round surfaces of any kind - stainless steel pipe, aluminum masts, fiberglass surfaces (including large ones), even nun buoys (without a reflector), make lousy radar targets. The reason is only that part of the beam that hits the surface perpendicular to the direction it came from will be reflected back to the transmitter. In order to be a good (read *bright*) target on someones radar screen there must be a good return signal. Birds, for example, can be seen but only as a low-quality target, and the same is true for other garbage and stuff out there on the water. I've seen many a boat without a radar reflector that didn't have any better signal than a small group of baby birds and that can be dangerous. How is someone able to descern the difference between a small group of birds and a boat that makes a poor target? If you go in the fog carry a radar reflector. Also keep in mind that if the sails are up they can seriously weaken the reflectors return signal if the signal has to travel through the sails. A reflector on the backstay will be visable over a wider arc than one mounted ont he side stays. There are good targets and bad targets and there are lots of bad targets. For your own protection you want to be one of the good targets.
Round surfaces of any kind - stainless steel pipe, aluminum masts, fiberglass surfaces (including large ones), even nun buoys (without a reflector), make lousy radar targets. The reason is only that part of the beam that hits the surface perpendicular to the direction it came from will be reflected back to the transmitter. In order to be a good (read *bright*) target on someones radar screen there must be a good return signal. Birds, for example, can be seen but only as a low-quality target, and the same is true for other garbage and stuff out there on the water. I've seen many a boat without a radar reflector that didn't have any better signal than a small group of baby birds and that can be dangerous. How is someone able to descern the difference between a small group of birds and a boat that makes a poor target? If you go in the fog carry a radar reflector. Also keep in mind that if the sails are up they can seriously weaken the reflectors return signal if the signal has to travel through the sails. A reflector on the backstay will be visable over a wider arc than one mounted ont he side stays. There are good targets and bad targets and there are lots of bad targets. For your own protection you want to be one of the good targets.
John, what type of radar are you refering to
John, I studied your post and haven't recalled an example of my radar being that ambiguous. If one doesn't have a good radar, then sure, get a good reflector. Speaking of reflectors, isn't it true that Practical Sailor found the low cost Davis reflector performed better than the expensive enclosed style?
John, I studied your post and haven't recalled an example of my radar being that ambiguous. If one doesn't have a good radar, then sure, get a good reflector. Speaking of reflectors, isn't it true that Practical Sailor found the low cost Davis reflector performed better than the expensive enclosed style?
John, are you busy today?
My boat is undergoing a rebuild in my backyard in Seabeck. If you have time, stop by and I'll give you a tour and buy you a cold one. Oh, my radar is hooked up and operational. I haven't adjusted for orientation yet. That has to wait 'till we launch in July. Maybe you have a reflector that you could bring along. We could put it on a pole and you could walk around the pasture until I see you on the screen and then I could adjust the relative bearing. I don't have a reflector. Threw it away when I realized how well I could see other targets. Just seemed the windage wasn't worth it. If you can't come out, here is our web site; http://members.tscnet.com/pages/ss427/Epitome's%20Rebuild.html
My boat is undergoing a rebuild in my backyard in Seabeck. If you have time, stop by and I'll give you a tour and buy you a cold one. Oh, my radar is hooked up and operational. I haven't adjusted for orientation yet. That has to wait 'till we launch in July. Maybe you have a reflector that you could bring along. We could put it on a pole and you could walk around the pasture until I see you on the screen and then I could adjust the relative bearing. I don't have a reflector. Threw it away when I realized how well I could see other targets. Just seemed the windage wasn't worth it. If you can't come out, here is our web site; http://members.tscnet.com/pages/ss427/Epitome's%20Rebuild.html
Fred - where in Seabeck?
Sure - where are you in Seabeck? That's a long drive out there! Radar: My radar is a Raytheon 10X, about 10 years old now, so it isn't as good at picking things up as yours. But a lot of units have been sold. It's advertised as a 16 mile radar but I run with it set much lower, say in the 3 mile range. Reflectors: My reflector is the Davis one which I have on the backstay. Drilled a few holes to install U-bolts in order to mount it in the rain-catch position. The backstay toggle will go through the hole in the middle of the reflector. One thing I learned that is interesting, according to Davis, having the plates at exactly right angles is very important. Even being 2 or 3 degrees off will seriously degrade the reflected signal. That would be one good reason for not buying one of those foil-coated cardboard reflectors. The diagram shows why rounded surfaces are such poor reflectors. If a radar was, say, a mile from a target and the target sent back a reflective beam, for the reflected beam to be received the angle would be really, really small. Thats probably why the settings for the gain and sensitivity is so critical (mine isn't automatic).
Sure - where are you in Seabeck? That's a long drive out there! Radar: My radar is a Raytheon 10X, about 10 years old now, so it isn't as good at picking things up as yours. But a lot of units have been sold. It's advertised as a 16 mile radar but I run with it set much lower, say in the 3 mile range. Reflectors: My reflector is the Davis one which I have on the backstay. Drilled a few holes to install U-bolts in order to mount it in the rain-catch position. The backstay toggle will go through the hole in the middle of the reflector. One thing I learned that is interesting, according to Davis, having the plates at exactly right angles is very important. Even being 2 or 3 degrees off will seriously degrade the reflected signal. That would be one good reason for not buying one of those foil-coated cardboard reflectors. The diagram shows why rounded surfaces are such poor reflectors. If a radar was, say, a mile from a target and the target sent back a reflective beam, for the reflected beam to be received the angle would be really, really small. Thats probably why the settings for the gain and sensitivity is so critical (mine isn't automatic).
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John, email me
John, My email is ss427@tscnet.com. Send a blerb and I'll give you directions. If you come down you'll see the car that the first part of the address is named after. Fred
John, My email is ss427@tscnet.com. Send a blerb and I'll give you directions. If you come down you'll see the car that the first part of the address is named after. Fred
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