am i missing something? most radar discussion i have seen stresses range and resolution, but isn't the main purpose of boat radar to spot nearby targets?
nautical radar range
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Target resolution is important tho. I think you'll find most people will keep it at two miles in coastal waters, four when further out and eight offshore. At 16, I can see a large ship if it is broadside and sometimes bow on, but usually at eight bow on. At twenty four. I can pick up high land masses only. Mine is a 24 nm 2.2 Furuno. It is my third Furuno. RD
Target resolution is important tho. I think you'll find most people will keep it at two miles in coastal waters, four when further out and eight offshore. At 16, I can see a large ship if it is broadside and sometimes bow on, but usually at eight bow on. At twenty four. I can pick up high land masses only. Mine is a 24 nm 2.2 Furuno. It is my third Furuno. RD
As Rick alludes to,
When you have a quality radar set you will soon learn what a great navigation tool it is. As great as GPS is, it's only capable of locating your vessel in a 'cocked hat' position. Sure, that's plenty good enough but radar shows your exact location as long as it's bouncing off reference points. Wonderful.
When you have a quality radar set you will soon learn what a great navigation tool it is. As great as GPS is, it's only capable of locating your vessel in a 'cocked hat' position. Sure, that's plenty good enough but radar shows your exact location as long as it's bouncing off reference points. Wonderful.
wonderful tool
I never knew how wonderful mine was until I went night sailing with it and force myself to learn how to REALLY use it. Here are some of the things I use it for. --Can heave-to and take a long nap by setting the radar alarm to 4 miles. --Can set the alarm to you blind side when you sail during the day and don't have to constanly check your blind spots for oncoming boats. -- To know where everybody is at night in a crowded area. Definately beats constant scanning and trying to judge distance at night. -- One screen to look at for speed, depth, other boats, time. I LOVE MY RADAR
I never knew how wonderful mine was until I went night sailing with it and force myself to learn how to REALLY use it. Here are some of the things I use it for. --Can heave-to and take a long nap by setting the radar alarm to 4 miles. --Can set the alarm to you blind side when you sail during the day and don't have to constanly check your blind spots for oncoming boats. -- To know where everybody is at night in a crowded area. Definately beats constant scanning and trying to judge distance at night. -- One screen to look at for speed, depth, other boats, time. I LOVE MY RADAR
Radar range
Different radar scanners (domes or open arrays, the antenna part of the system) are often descibed in terms of range (i.e. a 6 mile, 24, or 48 mile range). However, range isn't the most important element, as sooner or later all radars run out of horizon. Two other factors to consider are signal strength (power, usually 2kw or 4kw) and beam width (the physical size of the antenna). Using a flashlight as as analogy, consider beam strength the brightness of the bulb (to cut through fog, rain etc) and beam width as the ability to focus the light on specific targets. This allows you to distinguish targets from one another better. Consider two small fishing boats sitting close together 4 miles from your vessel. The smaller 2kw dome (smaller beam width won't focus the signal) may show one larger target. The larger 4kw dome or array (larger beam width focuses the signal) should return two smaller distinct targets. I just returned from a 2+ week cruise up to Princess Louisa Inlet and Desolation Sound. We had great weather but I still found my old Furuno 2kw CRT useful in detecting collision courses. It's fun to play with the EBL (Electronic Bearing Line) to determine if a target is going to cross in front or behind you (or collide with you unless one of you takes action!). It's also useful use the VRM (Variable Range Marker) to determine if you are overtaking or falling behind another boat on the same bearing. I recommend playing with your radar when visibility is good in order to gain experience and confidence for unexpected periods of low visibility (such as night and fog). Radar is relatively old technology but is still one of the most useful nav aids available. Best, Trevor
Different radar scanners (domes or open arrays, the antenna part of the system) are often descibed in terms of range (i.e. a 6 mile, 24, or 48 mile range). However, range isn't the most important element, as sooner or later all radars run out of horizon. Two other factors to consider are signal strength (power, usually 2kw or 4kw) and beam width (the physical size of the antenna). Using a flashlight as as analogy, consider beam strength the brightness of the bulb (to cut through fog, rain etc) and beam width as the ability to focus the light on specific targets. This allows you to distinguish targets from one another better. Consider two small fishing boats sitting close together 4 miles from your vessel. The smaller 2kw dome (smaller beam width won't focus the signal) may show one larger target. The larger 4kw dome or array (larger beam width focuses the signal) should return two smaller distinct targets. I just returned from a 2+ week cruise up to Princess Louisa Inlet and Desolation Sound. We had great weather but I still found my old Furuno 2kw CRT useful in detecting collision courses. It's fun to play with the EBL (Electronic Bearing Line) to determine if a target is going to cross in front or behind you (or collide with you unless one of you takes action!). It's also useful use the VRM (Variable Range Marker) to determine if you are overtaking or falling behind another boat on the same bearing. I recommend playing with your radar when visibility is good in order to gain experience and confidence for unexpected periods of low visibility (such as night and fog). Radar is relatively old technology but is still one of the most useful nav aids available. Best, Trevor
Not when you are out out there
When you are way offshore, you need to see far away ships. At their speed, they will come up on your boat real fast.
When you are way offshore, you need to see far away ships. At their speed, they will come up on your boat real fast.
A couple other achievements of radar:
Oh, IMHO. First, Radar won World War Two. Well, the History Channel shares my opinion too. Second, the defeat of radar bankrupted and brought down the Soviet Union, (Stealth) and ended the Cold War. Third, radar is the MOST significant invention ever. OK, there might be a couple of others that are big too, like the invention of the internal combustion engine and air conditioning but we don't have to speak German or Russian to enjoy those goodies. In short, get one, and prosper. Peace.
Oh, IMHO.
First, Radar won World War Two. Well, the History Channel shares my opinion too. Second, the defeat of radar bankrupted and brought down the Soviet Union, (Stealth) and ended the Cold War. Third, radar is the MOST significant invention ever. OK, there might be a couple of others that are big too, like the invention of the internal combustion engine and air conditioning but we don't have to speak German or Russian to enjoy those goodies. In short, get one, and prosper. Peace.
How long
what do you call real fast? 30 knots? Yeah, that's fast compaired to a sailboat, but even at 30 knots, you have plenty of time if they are 4 miles away. I use 4 miles because that's about all the clear range I find off the texas coast. We have lots of oil rigs and anchored ships all up and down the coast within 50 miles of the coast.
what do you call real fast? 30 knots? Yeah, that's fast compaired to a sailboat, but even at 30 knots, you have plenty of time if they are 4 miles away. I use 4 miles because that's about all the clear range I find off the texas coast. We have lots of oil rigs and anchored ships all up and down the coast within 50 miles of the coast.
You only "think" 4 miles is a long way off
Those ships will cover 4 miles real quick, and you need to get out of their way, and their wakes. They may also change course on you. This is critical especially if it is foggy, or at night, or poor visibility. IMHO, You need plenty of time to prepare, even if you are awake. You just don't want your boat to be their hood ornament. By the way, another benefit of radar is for other radar equipped boats, especially those big ships, to see you, if you have yours on.
Those ships will cover 4 miles real quick, and you need to get out of their way, and their wakes. They may also change course on you. This is critical especially if it is foggy, or at night, or poor visibility. IMHO, You need plenty of time to prepare, even if you are awake. You just don't want your boat to be their hood ornament. By the way, another benefit of radar is for other radar equipped boats, especially those big ships, to see you, if you have yours on.
yep, 4 miles is nothing, or so I learned when I
did an approach to the Chesapeake Bay (south end by Norfolk) a couple of weeks ago. Those freighters can look really far away when they are close and vice versa, and make judging their speed and intercept very hard. I’m getting a radar antenna for my Raymarine C80 display, I think the extra data from being able to track the ships within 10 miles or so will help allot.
did an approach to the Chesapeake Bay (south end by Norfolk) a couple of weeks ago. Those freighters can look really far away when they are close and vice versa, and make judging their speed and intercept very hard. I’m getting a radar antenna for my Raymarine C80 display, I think the extra data from being able to track the ships within 10 miles or so will help allot.
Many variables affect radar
For close in reduced ranges, the pulse rep rate increases (or should) giving more chances for getting a return echo. Combined with the stronger signal and generally better target geometry, it is better able to detect even a small target. A small antenna is not the problem for detecting nearby targets that it is for those further out. If you put the scanner lower to the water like on a pole or even on the cabin roof, a big antenna will not matter much since your range will be severely geometrically limited by curvature of the earth. Don't put the radar where your eyes are in line with or close to the transmitter as you may loose your color vision as a result of exposure to the radiation. The military guards on the DEW line in Alaska used to keep warm from the microwave radiation by standing near the antennas until they discovered that they lost their color perception. Out on the ocean, wave action, boat size and motion and statistically unfavorable geometry become factors that most people simply do not appreciate. To see a target, both boats must be at or near the crest of a wave. That is even more pronounced with bigger waves. Liken it to your ability to look over the crests of waves and see with your eyes even a large boat which is nearby let alone one far away. If you go higher, it is easier to see what is around you. Inside the radar itself, there are other technical design considerations which are quite important even if most people do not know what they are. Antenna size and design, signal amplifiers, switching circuitry, pulse widths, timing, rep rate, stability, and signal processing are some. Some of those things will vary somewhat in manufacturing and if you get a unit which has problems with one of more of these areas, you may see quite a difference in performance. I agree with Trevor and suggest that after installing one, you should take the boat out in good weather and see what targets look like when you can visually see them. If it doesn't meet your expectations, take it back. I like to install mine temporarily until I am satisfied with the performance. Two radars of the exact same kind may perform quite differently. Just be aware that when things get bad and the boat is in waves or heeled, things change quickly and it may not work so well. It also becomes very difficult to look at the display in rough weather. You may get sick. I like to have a good supply of ziploc sandwich bags at hand. No muss, no fuss and you do not have to get sick all over again cleaning it up. I think most people on small boats (inland or protected waters) use their radars mostly when it is foggy to see things close in. It is usually fairly calm when that happens but not always. My thinking is that it is best to mount the scanner as high as possible and on the strongest place you can find. Some boats do have radar detectors which will see your transmitted signal. I do not think that an operators license or a ships license is required for a radar unit. Fred, did you get one of those yet? The ships license used to be required but I think that has changed for small pleasure boats recently. Franklin, are you battened down for the weekend? Hope you are ok for Rita. You might want to take off your scanner and put it some place safe.
For close in reduced ranges, the pulse rep rate increases (or should) giving more chances for getting a return echo. Combined with the stronger signal and generally better target geometry, it is better able to detect even a small target. A small antenna is not the problem for detecting nearby targets that it is for those further out. If you put the scanner lower to the water like on a pole or even on the cabin roof, a big antenna will not matter much since your range will be severely geometrically limited by curvature of the earth. Don't put the radar where your eyes are in line with or close to the transmitter as you may loose your color vision as a result of exposure to the radiation. The military guards on the DEW line in Alaska used to keep warm from the microwave radiation by standing near the antennas until they discovered that they lost their color perception. Out on the ocean, wave action, boat size and motion and statistically unfavorable geometry become factors that most people simply do not appreciate. To see a target, both boats must be at or near the crest of a wave. That is even more pronounced with bigger waves. Liken it to your ability to look over the crests of waves and see with your eyes even a large boat which is nearby let alone one far away. If you go higher, it is easier to see what is around you. Inside the radar itself, there are other technical design considerations which are quite important even if most people do not know what they are. Antenna size and design, signal amplifiers, switching circuitry, pulse widths, timing, rep rate, stability, and signal processing are some. Some of those things will vary somewhat in manufacturing and if you get a unit which has problems with one of more of these areas, you may see quite a difference in performance. I agree with Trevor and suggest that after installing one, you should take the boat out in good weather and see what targets look like when you can visually see them. If it doesn't meet your expectations, take it back. I like to install mine temporarily until I am satisfied with the performance. Two radars of the exact same kind may perform quite differently. Just be aware that when things get bad and the boat is in waves or heeled, things change quickly and it may not work so well. It also becomes very difficult to look at the display in rough weather. You may get sick. I like to have a good supply of ziploc sandwich bags at hand. No muss, no fuss and you do not have to get sick all over again cleaning it up. I think most people on small boats (inland or protected waters) use their radars mostly when it is foggy to see things close in. It is usually fairly calm when that happens but not always. My thinking is that it is best to mount the scanner as high as possible and on the strongest place you can find. Some boats do have radar detectors which will see your transmitted signal. I do not think that an operators license or a ships license is required for a radar unit. Fred, did you get one of those yet? The ships license used to be required but I think that has changed for small pleasure boats recently. Franklin, are you battened down for the weekend? Hope you are ok for Rita. You might want to take off your scanner and put it some place safe.
NO....not yet.
I will be heading out in a few hours to take down my sails, bimini, and radar. Just talked to my dock neighbor and he took down his boom. I'm thinking about that but it's much more of a pain then his. Also going to put 12-14 dock lines on it and take everything out of the inside. Also have to turn the boat around so the bow is facing the south. Also have to see if I can find any replacements for the rubber lazorette latches that have busted off. If not, I guess I can try to tape them down. I'm glad I already bought my extra lines so I don't have to worry about finding some at the stores as I'm sure they're sold out by now. My boat will be ready...I sure hope the others are.
I will be heading out in a few hours to take down my sails, bimini, and radar. Just talked to my dock neighbor and he took down his boom. I'm thinking about that but it's much more of a pain then his. Also going to put 12-14 dock lines on it and take everything out of the inside. Also have to turn the boat around so the bow is facing the south. Also have to see if I can find any replacements for the rubber lazorette latches that have busted off. If not, I guess I can try to tape them down. I'm glad I already bought my extra lines so I don't have to worry about finding some at the stores as I'm sure they're sold out by now. My boat will be ready...I sure hope the others are.
radar
patrick, i think you have provided as good a description of why pilots don't fly in insturment conditions, eyes glued to radar, without guidance from air traffic control as i have ever heard. for my money, amateur sailboat radar is basically useful for near-in object avoidance.
patrick, i think you have provided as good a description of why pilots don't fly in insturment conditions, eyes glued to radar, without guidance from air traffic control as i have ever heard. for my money, amateur sailboat radar is basically useful for near-in object avoidance.
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