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It finally happened to me..FOG AT NIGHT
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Foggy



Joined: 01 Aug 2013
Posts: 1518
City/Region: Traverse City; Northern Lake Michigan
State or Province: MI
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C-Dory Model: 26 Venture
Vessel Name: Boatless in Boating Paradise
Photos: W B Nod
PostPosted: Wed Oct 11, 2017 7:02 am    Post subject: Reply with quote

"According to Rule 7b of the Colregs, vessels equipped with an operational
radar set are obligated to use it properly,
'including long-range scanning to
obtain early warning of risk of collision and radar plotting or equivalent
systematic observation of detected objects.' "

"Proper use" means more than putting the thing on "auto", fine tuning it for
existing sea conditions or mounting it where it won't fry your privates.

I wondered exactly what that meant so I took an Ocean Navigator course and
found out. It involves using a "maneuvering board and plotting sheet*" which
probably most recreational boaters using radar know nothing about. Without it
filled out in poor visibility and if a collision actually occurs, you may find yourself
on very thin ice legally. Found out it is not that difficult to do and could beat
investing in more stuff like AIS, FLIR, ARPA and MARPA devices.

The basics are here
* http://www.oceannavigator.com/January-February-2003/Rapid-radar-plotting/

Aye.

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smckean (Tosca)



Joined: 18 Jan 2014
Posts: 974
City/Region: Guemes Island (Anacortes)
State or Province: WA
C-Dory Year: 2005
C-Dory Model: 25 Cruiser
Vessel Name: Tosca
Photos: Tosca
PostPosted: Wed Oct 11, 2017 8:12 am    Post subject: Reply with quote

Foggy,

I can't image a boat of our size, which can stop and do 90° turns in a boat length, even considering doing radar plotting. This is for huge ocean going vessels who need to know many minutes in advance whether or not they are on a collision course.

I suspect most radar on our boats support MARPA....I know mine does. MARPA is sort of an automated radar plot. I also suspect most have not bothered to learn to use MARPA. I have just as an interesting technical exercise. I rarely use it.....altho I have done so to track freighters while I am in shipping lanes. I suspect I might use MARPA for any near vessel if I were in thick fog.

P.S. The old adage "Constant bearing means collision" is also VERY useful with boats of our size. That simple technique is more or less radar plotting and/or MARPA inside your brain. But, of course, it only works if you have visibility.
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Foggy



Joined: 01 Aug 2013
Posts: 1518
City/Region: Traverse City; Northern Lake Michigan
State or Province: MI
C-Dory Year: 2014
C-Dory Model: 26 Venture
Vessel Name: Boatless in Boating Paradise
Photos: W B Nod
PostPosted: Wed Oct 11, 2017 10:15 am    Post subject: Reply with quote

The Rule (not mine) doesn't mention boat size.

What you and I "imagine" may be quite different.

Aye.
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starcrafttom



Joined: 07 Nov 2003
Posts: 7878
City/Region: marysville
State or Province: WA
C-Dory Year: 1984
C-Dory Model: 27 Cruiser
Vessel Name: to be decided later
Photos: Susan E
PostPosted: Wed Oct 11, 2017 1:03 pm    Post subject: Reply with quote

smckean (Tosca)-I like what you said but you forgot one thing that to me does make radar in this area a must. " the other asshole" I can not tell you how many times I have seen a target on radar going 20 to 30 or more mph thru the fog. I see them and I stop and watch them go by at speed with their heads down starting in to a gps map WITHOUT RADAR. If I was in front of them they would never had seen me until they where half way thru my cabin. They are not looking up because the fog is to thick to see anything but because they have GPS MAPPING they think they came still go half speed and be ok. Only problem is that full speed is 45 to 50 so slow to them is 20. I have had it happen about twice a season for the past ten years. I would prefer they did not sell Mapping GPS with out radar. You dont need it and now that I have learned a few things
I could get by with out it. Its that other guy that worries me and I want to see him coming.

James- yes we have had some great fishing and sights in the fog. Its not all bad , if you know what is out there.

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smckean (Tosca)



Joined: 18 Jan 2014
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City/Region: Guemes Island (Anacortes)
State or Province: WA
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Vessel Name: Tosca
Photos: Tosca
PostPosted: Wed Oct 11, 2017 1:16 pm    Post subject: Reply with quote

Foggy,
Quote:
......or equivalent systematic observation of detected objects

This is part of the rule too. This is what I'm suggesting rather than manually drawing lines on a piece of paper. Also, note the phrase:, "vessels equipped with an operational radar set are obligated to use it properly" in the rule; so if you don't have radar, you are not obligated to drawing those lines on paper or anything else in this rule.

starcrafttom wrote:
I would prefer they did not sell Mapping GPS with out radar.

....and here I had you pegged as a libertarian.......hahahahaha
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starcrafttom



Joined: 07 Nov 2003
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PostPosted: Wed Oct 11, 2017 4:04 pm    Post subject: Reply with quote

I said prefer not demand, big difference.
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Foggy



Joined: 01 Aug 2013
Posts: 1518
City/Region: Traverse City; Northern Lake Michigan
State or Province: MI
C-Dory Year: 2014
C-Dory Model: 26 Venture
Vessel Name: Boatless in Boating Paradise
Photos: W B Nod
PostPosted: Wed Oct 11, 2017 4:29 pm    Post subject: Reply with quote

smckean (Tosca) wrote:
Foggy,
Quote:
......or equivalent systematic observation of detected objects

This is part of the rule too. This is what I'm suggesting rather than manually drawing lines on a piece of paper. Also, note the phrase:, "vessels equipped with an operational radar set are obligated to use it properly" in the rule; so if you don't have radar, you are not obligated to drawing those lines on paper or anything else in this rule.

starcrafttom wrote:
I would prefer they did not sell Mapping GPS with out radar.

SNIP


Many on this site are very cost conscious; mpg/fuel use.
That's why I mentioned a plotting board "is not that difficult to do and
could beat investing in more (relative large dollar) stuff like AIS, FLIR,
ARPA and MARPA devices."

Aye.
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smckean (Tosca)



Joined: 18 Jan 2014
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City/Region: Guemes Island (Anacortes)
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Vessel Name: Tosca
Photos: Tosca
PostPosted: Wed Oct 11, 2017 6:22 pm    Post subject: Reply with quote

Quote:
....could beat investing in more (relative large dollar) stuff like AIS, FLIR, ARPA and MARPA devices.


I'm not trying to be argumentative, rather I'm just trying to get the "facts" straight.

As I see it (maybe I'm wrong), the rule only applies to folks with radar. Without radar, the skipper only needs be vilgilant and has no obligation under this rule. If, however, you do have radar, then you have some obligations. What I'm saying is that MARPA is a much easier and faster way to meet that obligation than with pen and paper. MARPA is a software thing and does not require special equipment; the cost is only whatever the radar manufacturer decides to charge for that software feature.....it's software you have to buy anyway to have radar in the first place. I haven't checked pricing or availability, but my understanding is that there is no extra cost for this feature, it simply comes with your chart plotter unit. As far as I know, all, or nearly all, radar units come with MARPA. The issue is not cost, but familiarity.

P.S. Years ago I was the prime navigator on several ocean going sailboats. I have done trips of several days to several weeks, out on the open ocean, well out of sight of land. I loved navigation and found it interesting to navigate by sextant, watch, and tables (no one I sailed with back then had any electronic navigation equipment as we do today). I was quite good at this, and could not only do noon sights (for latitude), but I was also able to do twilight sights on multiple stars to find our immediate position (no dead reckoning estimation needed). All this required many hours of plotting lines of position, and course bearings on pieces of paper. So I am very familiar with what it takes to do such a thing. With that experience as a background, and IMHO, if you are alone, or don't have at least a helmsman with their eyes/ears peeled, and a second person who is knowledgeable to do the plotting down below, I have my doubts that attempting to hand plot positions and lines of intersection to various blips you see on your radar screen would be a safe thing to do. (Having said that, of course, alone or not, one better have a course to follow to a known destination with things like current set taken into consideration.)
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hardee



Joined: 30 Oct 2006
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City/Region: Sequim
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Vessel Name: Sleepy-C
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PostPosted: Wed Oct 11, 2017 6:50 pm    Post subject: Reply with quote

OK, Yes, if you have Radar from at least the last 10 years, then it very most likely has MARPA and yes, MARPA is and can be used as an adjuct for collision avoidance. When I first got SleepyC it was my first boat with radar. That was cool. Learning to use it was fun, a bit of a learning curve for sure, but after a while it was pretty natural.

Ferritting out the extra features, learning to tune it and taking full advantage of the features was the prime reason for many of those early trips.

MARPA was great, because I could use that to track other vessels and eithr get close, or stay away, depending on the circomstance. On my system, MARPA is not a one or two button function. (Maybe it is now on the newer units.) When I was doing it frequently, I could get the first plot in about 30 -40 seconds, and the you need to wait......until you have several minutes of passage, to do a second plot. That would then give you the course, approximate speed, and you can find out if you are in danger of collision.

That works, Yes. And for smaller vessels it may be the only way, BUT, those same small vessels are much less likely to maintain a speed or heading, SO, the reliability factor falls off some.

THEN I learned about AIS. In a w button push I have everything i need to know to maintain collision avoidance, PLUS (instead of just a spot on a screen), i know CPA "Closest Point of Approach", TCPA "Time to Closest Point of Approach", the size of the vessel, the speed, the course heading, the MMSI, and the vessel name. YES, all that in 2 button pushes, and it takes all of 5 seconds.

Is, AIS necessary, or Radar? No, not really, but I would say it depends on where you boat. Where I boat, I frequently cross some of the busiest shipping lanes in the country with freighters from 4-500 feet up to 1200 feet, and they are running at up to 25 knots. We have the busiest ferry service in yhe world in Washington state. They cruise at 18 to 25 knots, day, night, and weather whatever. All of those vessels are AIS equipped, and there are many smaller boats that are using AIS now, (broadcasting on a Class B device), which make all of these AIS triangles on my plotter, and in 5 seconds or less, I can have all of that info.

And Yes, I can do MARPA plots on those same vessels, but in the time it takes, I could be run over by a 1000 foot tanker doing 20 knots and the wouldn't even feel the bump. Sorry, but I am using the AIS as a primary device, and very rarely am I doing MARPA any more.

Harvey
SleepyC Moon

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thataway



Joined: 02 Nov 2003
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PostPosted: Wed Oct 11, 2017 7:45 pm    Post subject: Reply with quote

Philosophically I agree with smckean that it is highly impractical to use a plotting board on a C Dory, and for the reasons he stated. I also have many tens of thousands of miles as skipper of my vessels crossing oceans, and used basic non electronic navigation, as well as being trained in the use of radar plotting.

But as to MARPA, I'll quote from a Panbo article of Dec. 3, 2015
Quote:
" When a yachtsman says that MARPA is critical to safe navigation, I tend to wonder if they've been overly influenced by the commercial world where radar beam widths are much narrower and pulses much shorter."


Although this refers to a Navco unit--in many ways it refers to all small boat radars, and their ability. If you want the whole story, read it, the comments, and then various articles dealing with MARPA, the heading sensors etc.

I have the Garmin 24XHD radar, with a 1040xs--the combination supports MARPA --but to really get it to work, you need the extra heading sensor, with a second 10hz GPS receiver and a 9 axis sensor--"gyro rated" compass. (over $700). Retail price of all of this today is close to $4,000, including the cables and set up for the MNEA 2000 backbone. I am doing overlay at times--and a simulated MARPA without the special heading--but in reality I am only manually tracing one object. If I really want accurate information and I am lucky, I can use AIS do the projection in my head or maybe have to go back to a plotting board.. I lugged a pad of radar plotting sheets all over half of the World, but even in the stability of a 62 footer, with a real chart table, and one of the best small boat radars available in mid 1980's, things just happen too fast even at 6 knots with many targets to plot the objects! For an extreme example--we had over a dozen fishing boats, criss crossing pulling nets at one time--dense fog middle of the night within a 2 mile range You cannot plot that in real time.

The reality is that the C Dory is not a platform where you can manually even plot one vessel and still keep eyes on the radar, chart plotter (or overlay), depth sounder and keep a lookout--or respond to the person who is keeping a lookout, steer etc...

As to radar plotting--I do it in my head. Basically constant bearing is danger, just like visual. How accurate is your radar discrimination? Are there two boats at 5 miles or one? Without AIS, can you rapidly calculate how fast that boat is moving ( without MARPA)? Some of the latest digital radars are better. But as I understand today's technology, we are not quite there yet, without the very accurate heading sensor. (Some say that they can do it with the $200 point one), I have not tried that--and don't spend that much time in busy shipping lanes with fog--if I was in some areas--like Boston, I would have all of the latest equipment--if I wanted to run in those conditions. Don't forget one of those ferry's hit a breakwater not too long ago--what chance does a C Dory have?

A quote from a professional mariner on Cruising Anarchy

Quote:
MARPA can give you the general information that can be used to determine those targets that aren't really a threat and to identify those that may be a threat...... However, anyone who uses electronics to plot a technically correct close quarters route is foolish. There is a reason that my Night Orders book required a minimum CPA of 2 or 3 miles (at sea) and why other margins were usually considered in terms of miles or maybe half miles. You must keep a margin of safety far greater than what the decimal points tell you. The consequences of error are too big to consider.

A frequent failing of the average pleasure boater is that he thinks in terms of his own relative idea of close. To him a quarter mile is 1200 feet or twenty to thirty times his own boat length and between yachts that's a huge separation. But get to commercial shipping and it's not even half of their turning circle.

Use your AIDs to navigation but recognize their limitations. MARPA is just another aid like your compass for instance. Do you steer to the nearest degree or to the nearest 5, 10 or even 20 degrees?


How many C Dory's really use MARPA?

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JamesTXSD



Joined: 01 Mar 2005
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PostPosted: Wed Oct 11, 2017 8:17 pm    Post subject: Reply with quote

Use what you have and know. Learn about the options and decide what works best for your circumstances. And don't let someone on the internet, who may or may not have real world experience, try to goad you into anything.

Better equipment, properly used, makes a difference.
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starcrafttom



Joined: 07 Nov 2003
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PostPosted: Wed Oct 11, 2017 8:50 pm    Post subject: Reply with quote

I should not but what the hell. . Setting anything but a line of sight compass course on a small motor boat going 18mph or faster is wish full thinking. You can not do it alone thats for sure.

Any modern radar has MARPA and its real easy to use so why would you not use it??

If I did not have radar I would not go out in the fog. If caught in the fog I would work hard to find a place to hide until its gone. Worst case is slow and easy until I get back to a port and hope someone staring at their GPS going 20mph does not run me down.
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smckean (Tosca)



Joined: 18 Jan 2014
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PostPosted: Thu Oct 12, 2017 1:16 pm    Post subject: Reply with quote

thataway wrote:
As to radar plotting--I do it in my head. Basically constant bearing is danger, just like visual.

I do the same....more or less. "Constant bearing means collision" is my mantra for avoiding other vessels whether I have an actual visual on the other vessel, or because of poor visibility I only get a bearing to the vessel from a radar screen. Without a knowledgeable crew, as starcrafttom says, that's about all you can effectively do. I have used MARPA occasionally to track maybe one large vessel at a time (who is too big to change course or speed easily), but that's infrequent (but at least I know how to use MARPA!! Smile)

I only brought up MARPA in response to Foggy's point that the regs claim you must do blip tracking if you have radar installed. That's fine in an ideal world, but on a small boat like a CD while alone, or with an untrained crew, it's just not practical......so I guess I'm in violation and will continue to be Wink. I only posed MARPA in the sense that if you have radar you probably have MARPA, and if you must track, then it seems to me that MARPA is less likely to divert the skipper's attention and time than hand plotting would.

In the final analysis, I am pretty much exactly where starcrafttom is.
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starcrafttom



Joined: 07 Nov 2003
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PostPosted: Thu Oct 12, 2017 2:52 pm    Post subject: Reply with quote

Quote:
THEN I learned about AIS. In a w button push I have everything i need to know to maintain collision avoidance,


Well you know about everything that HAS AIS. its all the other small to big boats that do not have it or fail to turn it on that radar covers for me. Great tool but only part of the solution. Still waiting for a sent and receive unit for under $500 before I put it on. Remember most units are receive only. I have talked to several people that got receive only units installed and think that everyone can see them. They did not understand what they were buying but people where willing to sell it to them.

Talked to a guy on a cruising site that was under the impression that having radar made him more visible to other peoples radar.????????????? They are out there and they buy boats..
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smckean (Tosca)



Joined: 18 Jan 2014
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PostPosted: Thu Oct 12, 2017 5:01 pm    Post subject: Reply with quote

I agree with hardee that AIS is slick, but as starcrafttom points out, many vessels don't have transmitting units, so you can't see those vessels (I presume, Harvey, that this is your case too; so AIS helps you see others, but you are not helping them see you! Wink). I imagine it is great to have AIS blips (and all their associated info) right on your chart plotter with your GPS showing your boat's location on the same plotter; but that costs, and many of the chart plotters out there don't support AIS integration.

There is a "quick and dirty" solution that gives, in my estimation, 60% of the "I see you, but you can't see me" benefit.....namely, smart device apps. I bought a AIS app for my iPhone for $4.00 (mine's called "MarineTraffic"). Since AIS is required on all ships of 300 gross tonnage and all passenger vessels, I can see all the freighters and all ferries on the iPhone. Better would be putting the app on my iPad which I have mounted right next to my chart plotter with a suction cup bracket on the front helm station window. Unfortunately, my iPad does not have cell/GPS support; but if it did, I would have blips for all those big ships around me, and a blip for my boat on the iPad screen right next to my chart plotter.

So if you have a cell/GPS enabled iPad-like device, 4 bucks gets you most of what Harvey is raving about! OTOH, you have to be within range of cell service for this to work -- which is why I only give this solution a 60% grade.

P.S. I'm considering putting a cheap router on my boat giving me a boat-wide LAN using my iPhone as a hot-spot. Then if I buy a GPS enabled iPad (I actually borrow my wife's iPad now which doesn't please her Rolling Eyes), I'd have AIS, including my boat's blip, much of the time.....not to mention inter-connectivity for all my LAN supported devices (e.g., laptop) without all those wires hanging around as they now do. Also, with a LAN I wouldn't have to pay Verizon for another line just for the iPad.
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