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Old 22-03-2009, 06:05   #31
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Go to 广州磐博资讯科技有限公司 and read up on Lowrance/simrad's forthcoming digital radar. drastically lower power consumption, and much improved near-range target resolution. safer emissions too.

Chris
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Old 22-03-2009, 06:08   #32
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I'm on my second radar, the first a Vigil RM worked well enough to get me through some very foggy situations in ME and LIS. I used it when single handing offshore for passages by setting up guard zone alarms which I slept for 20 minutes.

It does use a lot of power however. But I rarely sail in fog and slow down and motor so the power issue becomes moot. Offshore on passages it's more of an issue.

I now have a RayC80 with radar and a NASA AIS. The Ray is improved over the Vigil and does CPA and keeps a MARPA list which is handy. Don't know how reliable it is, but the concept is great. Seeing the radar overlay on the chart is a very nice feature as well. You split screen the charts to different scales as well. Handy.

The AIS data is overlayed on the chart and there is a target list as well (like MARPA). Again the concept of AIS is great, but it given you info ONLY for ships with on and working AIS A or B transponders. I like the added info and the receiver was very inexpensive and easy to install. It is adding a bit of data and this adds to safety. I expect in a few years this will be greatly improved.

If you sail in areas of poor visibility (fog) or at night and where their is lots of traffic and "tricky" passages both Radar and AIS are very helpful and give you a bit more confidence and safety. If you can afford them, go for it.
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Old 22-03-2009, 17:11   #33
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Has anyone experience with AIS?
AIS is sometimes called "the poor man's radar". It's a bit misleading as AIS will only show AIS data sources (mostly ships but there some aids to navigation and even SAR aircraft that can be sources, too). It won't do anything about land masses, bridges, etc., nor will it show any vessels who are not sending AIS data.

As a piloting tool, it has great value. For sample of the data available from an AIS receiver, try this web site:
Live Ships Map - AIS - Vessel Traffic and Positions

Note, though, that it's plotted on Google maps. As an end user, it's up to you to decide how to display the data from an AIS receiver.
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Old 22-03-2009, 17:36   #34
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Another added benefit is that you can use your gained knowledge of radar operations to get out of speeding tickets on land. Throw out words like target masking, beam width propagation, range rate, scattering and LOS in court and helps.
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Old 22-03-2009, 18:05   #35
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Originally Posted by RBEmerson View Post
AIS is sometimes called "the poor man's radar". It's a bit misleading as AIS will only show AIS data sources (mostly ships but there some aids to navigation and even SAR aircraft that can be sources, too). It won't do anything about land masses, bridges, etc., nor will it show any vessels who are not sending AIS data.
Indeed, I even think it's dangerous to call it anything radar as some people will think it's a replacement for that.

There are some advanced shore radar stations (I know English Channel but there will be more) that will broadcast AIS for vessels that have no AIS but enter the area controlled by the radar station. Basically, they use the data from their ARPA radar and convert it to AIS. The other ships see the AIS target in the correct position with correct heading, speed etc.

They also make virtual markers from these shore stations. They show up just like navigation markers except when you go there you find nothing physically present. This is used for missing buoys or to mark recently sunk or grounded ships.

The latest use I heard off is that the ice berg hunters (planes) shoot AIS transponders into big icebergs. So, now you can see IceBerg21 coming for you ;-)

All this will eventually lead to full virtual reality coastal navigation I think.

cheers,
Nick.
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Old 22-03-2009, 18:38   #36
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I love radar (been in rain / fog with and without them), but do not have one and do not want one on my present boat. IMHO - for most small boats/low power budgets/limited budgets/simplicity - I might choose a chartplotter with AIS before radar.

On a larger boat in poorly charted / tropical areas I would want radar as well. But that is not my situation ...

IMHO the choices are more complex today than having a radar or not, and the smaller and lighter the boat the more carefully other choices have to be considered. Just one way to work your choices through is "What are the different uses of radar, and which of them can be done pretty well using different means with different costs?"

Benefits commonly listed for radar are:

Positional fixes (with risks for new players), particularly at night & in fog
Ship spotting / CPA calculations / etc, particularly at night & in fog
Squall spotting & monitoring, particularly in the tropics

Costs include:

Dollars
Weight & space
Power consumption

My chart plotter runs all day long consuming 0.6A, minimal space & weight. Tells me where I am more accurately than any radar, but sees neither ships nor squalls. But it still saves lots of work / anxiety at night & in fog. Strong caveats about positional fixes in poorly charted areas, and usual caveat vs. need for paper charts.

Adding AIS (separate or combo) adds 0.1-0.3A, and ideally needs own arial. Tells me where I am, relative to fixed navigational hazards. Tells me where transmitting ships and navigational aids are (mainly larger ones); has proximety / CPA alarms at low power cost. Active variants also tell big ships where I am. No use in spotting squalls (or cold fronts), but this is not a big issue pour moi.

Radar can be hungry for power, space & weight - but it is a wonderful tool for the well trained. Quite useful for navigation, when it shows what you think it shows. Sees ships with good radar cross section & alarms warn of ships while transmitting; performance varies with sea state, etc. Warns of some weather related risks.

Radar is a great tool: it excels in some tasks and in some conditions.
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Old 22-03-2009, 19:23   #37
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Originally Posted by hanschristian38 View Post
Fog in Maine? Well I guess a few day in the summer we get some fog.

I always found MARPA to be a great feature cruising off shore at night. It tracks targets and gives firing solutions if you have a canon. Alarms are also great at night.
That's hilarious...I never thought of it that way.

The consensus seems to be that once you have radar and learn to use it well, that it is really hard to give it up. I agree that having a radar can be a real benefit at times and sometimes a necessity. I just installed a navnet3d system....gawd I love that thing.
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Old 23-03-2009, 16:17   #38
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Any word on whether Raymarine will be coming out with any type of new generation / high def, low power, etc domes in the near future??

Have a c80 and may bite the bullet for radar someday!
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Old 23-03-2009, 16:25   #39
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There is a price for being an early adopter or... "he who lives on the bleeding edge, [often] gets sliced by the bleeding edge". Shop accordingly.
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Old 23-03-2009, 16:39   #40
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Love the Radar. Late crossing the banks in Bahamas once, got through North channel right at dusk and entered a strange harbor a couple hours later in the dark, anchored for the night and checked in in the morning. Crossing the stream... tracked water spouts to avoid them. From DR to PR predicted course to avoid heavy thunder cells at night. Avoided many larger freighters at night...It goes on and on. One of the most useful things ever....
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Old 23-03-2009, 18:37   #41
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The Coast Guard is already circulating an NPRM to extend AIS carriage requirements to include an additional 17,000 commercial vessels, and to raise the tab on running an AIS with incorrect information. This is good.

I think that any recreational vessel, power or sail, that uses waters frequented by big, cumbersome ships would be safer with an AIS receiver that could plot their positions and predict the potential for collision with them.

I think that radar should be aboard (and learned by the skipper of) any vessel large enough to carry it that has a budget that can afford it.

And I think these are two SEPARATE issues. Whether or not the AIS can talk, and whether or not it integrates with MARPA, are secondary considerations.

I also think that those who are so inclined should comment to the Coast Guard that it would be wise to expand the carriage requirement to more vessels; emergency equipment, tugs and barges, Sea Tow vessels, etc.
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Old 23-03-2009, 19:16   #42
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"poor man's radar"

Out of curiosity, and a vague intent to keel haul the reporter that let the term loose on the nautical world, I just did a moderately thorough search of the web for the term "poor man's radar" and it led right back here, and to SSCA. There was one hit on a news article, but it came after the earlier references. I looks like we created our own boogieman!

Does anyone remember seeing the term somewhere else before it popped up here?
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Old 23-03-2009, 19:58   #43
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I've seen it in the sailing press, probably Sail or Cruising World and possibly Practical Sailor.
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Old 30-03-2009, 10:53   #44
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Dear Friends,

For my own software project, I need arpa radar logfile full of NMEA sentences. The sentences I need ar $RATTM which indicate arpa radar tracks. I've searched the net but have not been successful in finding any sample logs. I have information about the sentence format however I need some sample log file to test if my software routines will be able to split and process the messages correctly.

Any help is appreciated,

Thanks in advance..

Quote:
Originally Posted by cabo_sailor View Post
I expect you'll get a lot of feedback on this one because there are no simple answers IMO. Yes I do have radar, and yes I use, at night and when visibility are down. BUT... there's always a but isn't there.

It does chew up power, it's something else to maintain. Mine is on the fritz at the moment with a "scanner inoperative" message. Beyond that, they do take some time and trouble to learn how to read one. Even more time and trouble to use a good majority of the tacked on programming goodies.

Then you have to decide how much power. It is my opinion that in order to punch through even light rain I need the 48 mile or 4 kw unit. It's not that I expect to see 48 miles cause I won't given the height of the antenna but the extra power also provides a bit better resolution. I'd get even a bit better resolution if I had an open array antenna instead of the radome.

See what I mean, be prepared to do some research and then studying if you do get one.

Finally, I know some people that don't want one because of the potential legal liability. You hit someone or something in poor visibility and you were NOT using radar or using it improperly then the issue of liability comes up because you weren't using all your resources.

Having said all that.... I'll get mine fixed and continue to use it.

By the way, in a real squall line don't expect to see much. Even the 4 kw doesn't have that kind of power. It'll show it coming but once into it, fugadabout it.

As I said I expect this might open a can of worms. In the words of the chairman on Iron Chef....."Let the BATTLE begin!"

Rich
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Old 30-03-2009, 12:18   #45
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I had no trouble seeing squall lines, wind spouts, thunderstorms etc 6 - 10 miles out with both my old Furuno's I believe they were 24 mile units.... 24" dome...?
Power consumption was never really an issue overnight sailing. You dont have to run it all the time. Sure is nice for avoiding Thundersqualls at night in the Carribean though!
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