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Vessel detectors
Derek Weston wrote:
... electronic means to automatically detect vessels ... are of great value to us. We have a radar with a watch facility which is great, except it draws 30-odd watts, more that we can afford ... In general your solutions appear to be a bit more complex than is absolutely necessary. Just my point of view, of course. For example, my small Furuno "watches" on a scheduled basis and draws very little. You might want to consider a more energy-efficient radar. ... Our radar detector works well, but ships often have their radars switched off. Are you sure of this, and if so, how? You are suggesting that these commercial vessels are operating illegally (which of course is possible, but, en masse, unlikely). 1) Nav light detectors ... [details snipped] ... I am not an electronics designer, but this setup seems beyond the financial and maintenance abilities of a typical small boat sailor. 2) Hydrophone systems Perhaps a ships prop or other ship noise can be detected electronically. This leaves out vessels not propelled by machinery. In any case a small sonar seems like a good possibility compared to the optical device above. -- Good luck and good sailing. s/v Kerry Deare of Barnegat http://kerrydeare.tripod.com |
Vessel detectors
For one thing when you sail alone you have alarms set on the radar, wind,
depth, and gps. You're only cat napping for a few minutes at a time unlike sleeping for 8 hours. The only idiots I know that do this are the Volvo Ocean Racers, which is a sanctioned race. Sea or admiralty law states if your boat is equipped with radar and your not using it when you have an accident your at 50%fault. This includes being struck by other vessels. Jack's two cents "Larry" wrote in message ... On 17 Aug 2003 00:41:30 -0700, (Derek Weston) wrote: We shorthand frequently on our sailboat, and electronic means to automatically detect vessels in our area are of great value to us. We have a radar with a watch facility which is great, except it draws 30-odd watts, more that we can afford as we're primarily solar panel powered. Our radar detector works well, but ships often have their radars switched off. Two ideas I've been mulling over to which others may be able to contribute useful ideas: 1) Nav light detectors I think it may be possible to devise an electronic system which can detect red and green coloured lights, and distinguish these from the moon and the stars. I'm imagining a rotating system with a cylindrical lens and both red-filtered and green-filtered detectors, and triggering an alarm on the basis of the magnitude of the difference between the two sensor outputs. With appropriate relative gain settings, the moon and the stars could give a near null result, while coloured nav lights may give a greater output sufficient for the alarm trigger. This may be close to the limits of present technology. I can imagine the sensors may need to be cooled (with consequent condensation problems). How are you going to filter out white light from the stars? It contains red and green, too. What about power boats only displaying white and red or white and green unless they are headed straight for you? What about coming up on the stern of that 950' containership at anchor? Better stick with the radar and get a shaft alternator or wind bugger, instead.....please? 2) Hydrophone systems Perhaps a ships prop or other ship noise can be detected electronically. US Navy has gotten so good they can tell you WHO the ship is from the sonar signature. Not sure they can tell what underwear the captain and first mate are wearing, yet, but they're working on it at MIT. You'll have to listen, as I have, to the passive sonar in a Trident nuclear sub and see how much equipment is necessary to do what you're thinking. It sure won't run on 30 watts off a solar panel, though. Oh, did I mention the shaft alternator and windbugger work at NIGHT?...(c; Any thoughts, previous work, intelligent comments.... Derek Weston Talking Marine Instruments http://www.alphalink.com.au/~derekw/mit/apps.htm I don't know what Oz's admiralty thinks about it but here in the States the rules say you must "maintain a lookout", whatever that means. Yeah, there are idiots sailing Around The World Alone sleeping in their bunks. Amazing how they survive as long as they do. Lucky for them it's a big ocean. Larry Extremely intelligent life must exist in the universe. You can tell because they never tried to contact us. |
Vessel detectors
Derek Weston wrote:
We shorthand frequently on our sailboat, and electronic means to automatically detect vessels in our area are of great value to us. We have a radar with a watch facility which is great, except it draws 30-odd watts, more that we can afford as we're primarily solar panel powered. Our radar detector works well, but ships often have their radars switched off. Two ideas I've been mulling over to which others may be able to contribute useful ideas: 1) Nav light detectors I think it may be possible to devise an electronic system which can detect red and green coloured lights, and distinguish these from the moon and the stars. I'm imagining a rotating system with a cylindrical lens and both red-filtered and green-filtered detectors, and triggering an alarm on the basis of the magnitude of the difference between the two sensor outputs. With appropriate relative gain settings, the moon and the stars could give a near null result, while coloured nav lights may give a greater output sufficient for the alarm trigger. This may be close to the limits of present technology. I can imagine the sensors may need to be cooled (with consequent condensation problems). 2) Hydrophone systems Perhaps a ships prop or other ship noise can be detected electronically. Any thoughts, previous work, intelligent comments.... Derek Weston Talking Marine Instruments http://www.alphalink.com.au/~derekw/mit/apps.htm Years ago a marine publication recommended buying a standard traffic radar detector. Seems that they are so broadband that they will pick up nearly everything in the radar band. Owing to philosophical objections to the practice, I've never owned one, but it might be worth testing. I should think that anything of 'size' at night would be equipped with, and using, radar. |
Vessel detectors
On Sun, 17 Aug 2003 15:30:46 GMT, Chuck Bollinger
wrote: I am surprised by the above. Can you provide some documentation? I had thought it was the other way around: Use of a radar did not obviate the requirement for a proper lookout. I'd like to see that, too. Of course, OUTSIDE the jurisdiction of a country's authority I don't suppose there's anything CG would do about it. Larry W4CSC Maybe we could get the power grid fixed if every politician regulating the power companies wasn't on their payrolls. |
Vessel detectors
x-no-archive:yes
(Derek Weston) wrote: We shorthand frequently on our sailboat, and electronic means to automatically detect vessels in our area are of great value to us. We have a radar with a watch facility which is great, except it draws 30-odd watts, more that we can afford as we're primarily solar panel powered. Our radar detector works well, but ships often have their radars switched off. Our radar is a LCD which I think doesn't take that much power. THe real power hog is the Autohelm. If you are on watch alone or are singlehanding, are you not using some form of steering? Of course maybe you are using a wind vane, which doesn't take power. However IME, people don't use wind vanes much unless they are experienced BW cruisers. Someone has suggested a wind generator. When we are sailing (which I presume you are, else the power needs of the radar wouldn't be a problem), we don't get a lot of use from the wind generator even though it isn't dependant on the light. Either the wind is too light to put in any amps, or the sails blanket it so it doesn't get any wind. In any case, of the suggestions made, I think an auto radar detector or a less power hungry radar are the best solutions. Or perhaps a battery bank that can store more amps so that you have more of them available. Two ideas I've been mulling over to which others may be able to contribute useful ideas: 1) Nav light detectors I think it may be possible to devise an electronic system which can detect red and green coloured lights, and distinguish these from the moon and the stars. I'm imagining a rotating system with a cylindrical lens and both red-filtered and green-filtered detectors, and triggering an alarm on the basis of the magnitude of the difference between the two sensor outputs. With appropriate relative gain settings, the moon and the stars could give a near null result, while coloured nav lights may give a greater output sufficient for the alarm trigger. This may be close to the limits of present technology. I can imagine the sensors may need to be cooled (with consequent condensation problems). 2) Hydrophone systems Perhaps a ships prop or other ship noise can be detected electronically. Any thoughts, previous work, intelligent comments.... Derek Weston Talking Marine Instruments http://www.alphalink.com.au/~derekw/mit/apps.htm grandma Rosalie |
Vessel detectors
I never said that you are not to have a proper lookout. Under the law you
are to use all means available to avoid a collision. By having RADAR and not using it you're at fault. Even if the another vessel collides with your boat, you will be fault for not operating your RADAR. To avoid a collision. Jack "Chuck Bollinger" wrote in message ... Jack Rye wrote: Sea or admiralty law states if your boat is equipped with radar and your not using it when you have an accident your at 50%fault. This includes being struck by other vessels. Jack's two cents I am surprised by the above. Can you provide some documentation? I had thought it was the other way around: Use of a radar did not obviate the requirement for a proper lookout. |
Vessel detectors
Subject: Vessel detectors
From: Chuck Bollinger Years ago a marine publication recommended buying a standard traffic radar detector. Seems that they are so broadband that they will pick up nearly everything in the radar band. Owing to philosophical objections to the practice, I've never owned one, but it might be worth testing. "Philosophical objections" to owning a radar detector to pick up ships radar!? OK Chuck, I got to hear this one. Capt. Bill |
Vessel detectors
"Armond Perretta" wrote in message ...
Derek Weston wrote: ... electronic means to automatically detect vessels ... are of great value to us. We have a radar with a watch facility which is great, except it draws 30-odd watts, more that we can afford ... In general your solutions appear to be a bit more complex than is absolutely necessary. Just my point of view, of course. For example, my small Furuno "watches" on a scheduled basis and draws very little. You might want to consider a more energy-efficient radar. I don't think there is one, but would certainly be happy to be corrected. From what I have determined, 30W is typical for keeping the magnetron "alight" between periodic scans. ... Our radar detector works well, but ships often have their radars switched off. Are you sure of this, and if so, how? You are suggesting that these commercial vessels are operating illegally (which of course is possible, but, en masse, unlikely). Yup, quite sure of it. We have a radar detector on board. Others have found the same: "It's also interesting to note that during the transatlantic, an alarming number of vessel's contacted to evaluate our radar return, responded willingly but said, "please wait while I turn on the radar!" from http://www.ussailing.org/safety/Stud...arenhancer.htm 2) Hydrophone systems Perhaps a ships prop or other ship noise can be detected electronically. This leaves out vessels not propelled by machinery. True. |
Vessel detectors
Terry Spragg wrote in message
I seem to recall some one devising an 'all around' lens that focuses on a colour ccd camera. Any red or green light and it's bearing would be detected in logic, and no scanning mirrors would be required. Right. Thanks for the info and comments. I'm discouraged by my observation that night capable CCDs all seem to have peltier cooled sensors. If you have ever heard powerboat engine and prop noise transmitted through the water and hull while enjoying a quiet sail, you would think it possible to detect approaching ships like submariners and antisubmariners do. Speech recognition logic can recognise any sound it is trained to. As it can be sensitive to specific voices, it could be attuned to high speed or heavy props, or both, along with whales, which talk and blow a lot, seemingly, and slop sounds from semi submerged containers of certain volume and exhibiting audible resonances, etc. Three hydrophones should be able to determine bearings of noise sources, if not their source noise echos near shore. A high rate repetiton sonar pinger and interleaved range gating logic may be able to catch repeated MTI type returns, as opposed to wave face clutter in deep waters. There is no reason why sophisticated analysis engines could not be mass produced on microchips except cost, which depends on scale of production. In the meantime, logic development might have to do. What more engrossing passtime could a long distance sailor wish for? Indeed. I think I may do some experiments along this line. Wouldn't help detecting other yachts, but none of the options (including a good human lookout) is perfect. |
Vessel detectors
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Vessel detectors
In article ,
says... (Larry) wrote in message ... How are you going to filter out white light from the stars? It contains red and green, too. I was imagining determining the difference in magnitude between the red and green signals, 'though there are other possibilities for differentiating between starlight spectra and nav light spectra. If your boat is moving, you could well be on a collision course that would allow you to see only the red or only the green light. That makes the problem more difficult. Furthermore, on a moonlight night, you will have to contend with reflections off the wave tops. Those will have transient levels of red and green that will complicate the detection problem. Overall, it looks like this type of sensor would require quite a bit of spectral discrimination and tracking intelligence. What about coming up on the stern of that 950' containership at anchor? Unlikely mid ocean :-) Better stick with the radar and get a shaft alternator or wind bugger, instead.....please? Well maybe, but what I've learned from this thread, my own observations and others remarks is that nothing (including radar and an alert watchkeeper) will detect everything which may cause a problem. .... Lucky for them it's a big ocean. Indeed. But it really is a big ocean - I can recall three two week stretches at sea when we saw absolutely no other vessels. IIRC, on one crossing from Tahiti to LA, we saw no other vessels at all. I suppose some may have popped up on radar, though, that I didn't know about. Our radar had quite good range, too. But then I was aboard a 400' missile range tracking ship at the time! Mark Borgerson |
Vessel detectors
Armond Perretta wrote:
In any case a small sonar seems like a good possibility ... Sound waves bend downward creating a blind zone near the surface. |
Vessel detectors
Vito wrote:
Armond Perretta wrote: In any case a small sonar seems like a good possibility ... Sound waves bend downward creating a blind zone near the surface. Quite, but the sound waves generated by the target vessel do themselves propagate in a uniform direction from the source, so they _will_ be picked up. -- Good luck and good sailing. s/v Kerry Deare of Barnegat http://kerrydeare.tripod.com |
Vessel detectors
"Armond Perretta" wrote in message ...
Vito wrote: Armond Perretta wrote: In any case a small sonar seems like a good possibility ... Sound waves bend downward creating a blind zone near the surface. Quite, but the sound waves generated by the target vessel do themselves propagate in a uniform direction from the source, so they _will_ be picked up. The trouble is that the original poster was concerned about power consumption on his radar. I can't imagine that a sonar solution could get away with anything less than a fairly powerful PC running to do the signal processing, you need to filter out all the false stuff including noises from your own vessel. Even so, for boats with the power to keep it running, it would be very interesting technology. The obvious use is for single-handers but, even for crews maintaining a 24 hour watch, humans can get tired and have lapses of concentration so an extra "safety net" would be very useful. - Julian. |
Vessel detectors
Julian wrote:
"Armond Perretta" wrote ... ... the sound waves generated by the target vessel do themselves propagate in a uniform direction from the source, so they _will_ be picked up. ... for boats with the power to keep it running, it would be very interesting technology. The obvious use is for single-handers but, even for crews maintaining a 24 hour watch, humans can get tired and have lapses of concentration so an extra "safety net" would be very useful. I have many times, in clear conditions and with "unlimited" visibility, had the radar pick up targets that I probably would have missed using only binoculars and a steady hand (even assuming that I was at the time being diligent). I am not suggesting that one should rely _only_ on electronic aids, but if they can be supported financially, maintenance-wise, and power-wise, I think the decision gets fairly obvious. -- Good luck and good sailing. s/v Kerry Deare of Barnegat http://kerrydeare.tripod.com |
Vessel detectors
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Vessel detectors
What I don't understand is why a ship would turn off their radar. Are they trying to save the few watts of power? Are they trying
to reduce wear on the radar? Does it interfere with their satellite TV? It seems the cost of operation is so low compared to the potential consequences that there would be no motive to turn it off. On 20 Aug 2003 08:11:15 -0700, (Jim Woodward) wrote: I don't know about 50% at fault, but the Colregs are pretty clear: Rule 4: Rules in this section apply to any condition of visibility. Rule 5: Every vessel shall at all times maintain a proper lookout by sight and hearing as well as by all available means.... Rule 7(a) Every vessel shall use all available means appropriate to the prevailing circumstances... Rule 7(b): Proper use shall be made of radar equipment if fitted and operational,... In other words: 1) Keep a visual lookout. 2) If you have radar, you shall use it. Jim Woodward www.mvfintry.com -- Chuck Cox SynchroSystems Motorsport Computers Hopped/Up Racing Team http://www.synchro.com |
Vessel detectors
You'll always have a few who work under the assumption that less usage
is better for longevity. However, many companies now require at least one radar on at all times, underway (the other on stby), and some require both. Maybe someday you'll be able to rely on all ship's having at least one radar on, but you'll never see the day when someone will be assigned to constantly monitor it, although, with the newer bridge consoles and seating arrangements, this is improving, EG to the detriment of the walk around visual watch. otn Charles Cox wrote: What I don't understand is why a ship would turn off their radar. Are they trying to save the few watts of power? Are they trying to reduce wear on the radar? Does it interfere with their satellite TV? It seems the cost of operation is so low compared to the potential consequences that there would be no motive to turn it off. On 20 Aug 2003 08:11:15 -0700, (Jim Woodward) wrote: I don't know about 50% at fault, but the Colregs are pretty clear: Rule 4: Rules in this section apply to any condition of visibility. Rule 5: Every vessel shall at all times maintain a proper lookout by sight and hearing as well as by all available means.... Rule 7(a) Every vessel shall use all available means appropriate to the prevailing circumstances... Rule 7(b): Proper use shall be made of radar equipment if fitted and operational,... In other words: 1) Keep a visual lookout. 2) If you have radar, you shall use it. Jim Woodward www.mvfintry.com -- Chuck Cox SynchroSystems Motorsport Computers Hopped/Up Racing Team http://www.synchro.com |
Vessel detectors
On many ships, you will find the alarms turned off (too many false
alarms) although this too is improving. To avoid many of these false alarms, either the inner guard ring is moved out to a range where small boats may not be detected, or sea return is turned up to a point that close in targets can be and are lost. Much of what is needed, is training and procedures. The Mates need to be trained to frequently check the screen (and not just rely on alarms) but also to scan the various ranges .... especially the lower ones. In most cases at sea, shipboard radars will be set on either the 12 or 24mi. range, for early detection (with "sea return" minimized for best reception) .... problem with this is that many small close in targets can be missed. otn Vito wrote: otnmbrd wrote: Maybe someday you'll be able to rely on all ship's having at least one radar on, but you'll never see the day when someone will be assigned to constantly monitor it, .... True. FWIW, the US Navy did studies that showed a skilled alert operator could detect almost all new contacts but that one's alertness quickly waned so that, after an hour or so detection became iffy. That's why we spent megabucks to develop automatic detection and tracking sustems. Also, the higher the antenna the longer the range but the poorer its ability to "see" small craft in the sea clutter, especially close aboard. So never, ever depend on a big ship seeing you. 73, K3DWW |
Vessel detectors
Please forgive me if this was covered in a previous post, but can someone
briefly advise of the utility of off-the-shelf automobile type detectors for use at sea. Are they completely useless or just unreliable enough to make them dangerous? Craig |
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