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Old 12-15-2012, 11:48 AM   #1
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Dead Reckoning

Do any of you rely solely upon dead reckoning with chart, compass and depth finder?

How about partially?

50+ years ago folks went recreational boating without I-Pads, chart plotters and radar. Reading threads about electronic navigation aids leads one to wonder if folks leave the dock without them anymore.
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Old 12-15-2012, 11:58 AM   #2
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We do a lot when navigating channels like the ICW. Really all you need is a chart/chartbook, a good pair of binoculars and a depth finder. I like to "partially" when on extended passages, in shore or off, by marking our position course and speed on the paper chart at regular intervals, and in the log. That way if the electronics go out, you can calculate pretty accurately where you are. It's also kind of nostalgic to look back and see where you've been in past years.

I enjoy taking bearings, calculating the effects of current etc as kind of a sport and to keep my fairly limited traditional navigation skills somewhat intact.
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Old 12-15-2012, 12:13 PM   #3
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I'm probably the closest to that but I have radar, a big chart plotter, 2 sounders the VHF and a compass.

However I never plot courses or play w waypoints ect. I don't play electronic games either.

Several times in dense fog I have "observed" a course and run that course by the compass.

But having radar and a plotter is a far cry from dead reckoning. In the past I've done dead reckoning w/o even a chart. Not by my choice however. Must have been a really busy summer as there was no charts available at all. Had to run my OB boat from Ketchikan to Juneau w a green and blue map made for tourists by the forest service. I got quite good at recognizing islands ect and judging my position relative to them but I had to rely on kelp to stay off the rocks. It was the best boat trip of my long life.
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Old 12-15-2012, 12:55 PM   #4
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Back in the '70's when we were cruising as liveaboards, our offshore navigation was with a flasher/sounder, Texaco charts and a cheap 'am' transistor radio...find a station on the radio, identify the broadcast tower on the Texaco chart, turn the radio until the sound quit and you have a bearing. The depth on the NOAA chart gave us our fix. Even without using the chart for reference, if you picked up a Jacksonville station, you knew you were near Jacksonville...


Then I built a Heathkit RDF with frequency readout and could "ZBB" all the way to Bimini. But the transistor radio was still my preference especially in the Chesapeake where there were a gazillion beacons.


We did learn Celestial with the Zenith Transoceanic Radio for "tock, tock, tock, beeeep", sight reduction tables, and a cheap Davis plastic sextant but never found it necessary to use any shots for navigation.

For inland navigation (ICW) it was chartbooks but seldom a plot.

Now, no paper, no compass, no radar...just GPS.

I do remember one time sailing across the Bahama Banks from Gun to the Berrys. We needed 4' and there's a lot of shallow reefs, I was sooo glad when we spotted a marker on the way across - now I could see exactly where we were and know if we had been getting set. But when I found it on the chart, guess what? It was a "PA"...but better than nothing.
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Old 12-15-2012, 01:55 PM   #5
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If you cruise Mexico you will have do some dead reckoning. On the Pacific coast some of the chart surveys are from 1905 or earlier. Isla Isabel is .6 miles from its charted position. On the East coast, Puerto Morelos is off 2 miles. Radar will help identify land mass but it's not much good for submerged rocks and reefs. Most commercial harbor charts have been updated. We spent 4 plus years cruising the area and after a while you use the charts to get you in the general area then you pay attention, just like the old days. It was a treat though when we left and found areas that charts were accurate.
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Old 12-15-2012, 02:25 PM   #6
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Greetings: Perhaps you misspelled the word "dead". It should be "ded-reckoning". You deduce your location based on time/speed, visual views. A sextant could at best give you a location of about 5/10 sq miles. We have moved forward to the point where Bowditch, Dutton and others have been placed in museums. The newey boater does not even carry paper charts nor is able to find a GPS position on one.
Our navies now rely on electronic devices and have even done away with Starboard and Port. Right/Left. Oh yes, the newey knows not what "reciprocal" is both boating and in many other relationships.
We conn most boats using the age old techniques of piloting, Navigation for most is a missused word as they are never ever out of site of land.
As an aside, I remember when Texaco put out those wonderful maps, not for navigation but to give you the large picture of area. A road map still has its place. Bill.
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Old 12-15-2012, 02:52 PM   #7
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CPs: I forgot another masterful book, Griffiths, Practical Piloting and Seamanship, Canada's compliment to Chapman. Bill
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Old 12-15-2012, 03:52 PM   #8
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We know how to use dead reckoning, we have the charts and tools to do it, and we have plotted the courses we use the most in our big chartbooks in the event the electricicals keeping the plotters running should stop holding hands. But we don't actually run the boat this way.

We do, however, hold our heading with the magnetic compass, checking it frequently against the two plotters to see if we need to hold a different heading to maintain the course.
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Old 12-15-2012, 10:22 PM   #9
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I know how to dead reckon, but don't do it. I also know how to use a sextant and using the celestial tables, triangulate my position, but I don't do that either. I do carry paper charts for the areas I travel and I always track my position on the chart plotters and confirm it visually. In the delta, the fog can form quickly and in pockets, so those old forms of navigation on the serpentine rivers and shallow sloughs can be inadequate.

Last Tuesday I was traveling down the Mokelumne River in 1 mile visibility. No problem, I thought. As I turned east onto the San Joaquin River, the visibility quickly fell to 1/16 mile as measured on the channel markers as I passed them downstream. I pulled into 3-mile slough and crept my way toward Brannan Island State Park, barely able to see the shore a couple hundred feet away. Once in the safe waters of the no wake zone near the park, I dropped anchor and waited more than an hour for the fog to dissipate. If I was on the river trusting old methods, I could have quickly found myself aground on a shoal or shore.

This picture shows river debris found on the Sacramento River in approximately 1/2 mile visibility which no electronics can help me avoid, but it also shows that the shore is barely visible under these conditions. My radar was cluttered with echoes of debris and hyacinth floating down the river, easily masking other river boat traffic to the untrained eye.



To me, radar, multiple chartplotters and great attention were required under these conditions to safely navigate. Am I a slave to technology? Some would say yes. I say I'll use it to safely operate my vessel in less than optimum conditions. Without the digital edge, I would have had to anchor near the main river channel hoping to avoid being overrun as my horn sounded every two minutes.

Due to electrical interferences from fans, wipers and radios, I find my GPS compass to be much steadier and more accurate/reliable than my whiskey compasses. I cross check to get a relative deviation between the two, but rely on the electronics to guide me when the going gets rough.
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Old 12-15-2012, 11:47 PM   #10
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I always start out my plotting and actual start using Ded Reckoning. When I didn't have a GPS or LORAN, I would get a fix using known objects on a chart such as light houses, airport lights and other landmarks and immediately adjust my heading. Now with GPS, your cross track error is immediate and adjustments are made along the way and recorded. It only makes sense. Ded Reckoning should only be used if you are clueless as to wind speed and direction, tide and current changes and no way to take an accurate fix on your position from time to time.
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Old 12-15-2012, 11:48 PM   #11
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Quote:
Originally Posted by CPseudonym View Post
Do any of you rely solely upon dead reckoning with chart, compass and depth finder?
I would say that piloting is a more accurate description of what I do for near coastal navigation. I always have a paper chart, and there is a hand bearing compass (and binocs w/ compass) nearby. Fun to keep in practice.

I do have a gps, radar, and PC nav programs. Be silly not to. But I have never hooked up the PC to the autopilot. There are books of published waypoints from WA to AK. There is one off of Grief Point near my house. During the summer there is a parade of boats going to Desolation Sound. By watching the relative bearing of boats coming to the point, you can tell which boats have the waypoints programmed in and predict their turns with uncanny accuracy. What fun is that?



Quote:
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Our navies now rely on electronic devices and have even done away with Starboard and Port. Right/Left.
Submarine navigators dead reckon, sometimes for days, Yes they do have inertial navigation, which is likely more accurate now than in my day, but the QMs still plot DRs in between GPS fixes.

Right and Left have been rudder commands for 90 years now...and for a good reason.
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Old 12-16-2012, 03:24 AM   #12
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I still always double check the GPS & depth readings against the local charts, either full oceanographic charts if out at sea, or the local and regularly updated book of waterway maps done especially for our bay and the coast associated with the bay. In the bay especially we have a lot of narrow channels and therefore a lot of channel marker buoys or beacons, and the GPS can be out a bit, so it pays to check which side of the beacon one should go, for example, because they have to move them from time to time as the channels move, not always caught up with on the chip you are using, and just to add to the fun, because of the rules, the beacon directions can change in unexpected ways, as one moves from East/West channels to North/South channels, etc.
Having said that, when traveling at night especially, boy do I love the GPS. Traveling along just guided by winking lights is not my idea of fun. Radar as well would also be nice.
I love technology. But in case of power failure it still pays to be able to read a map, right..?
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Old 12-16-2012, 07:58 AM   #13
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Always paper chart and hand held GPS.

Keep up a running fix so no DR is required till the GPS sats get fried.
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Old 12-16-2012, 09:31 AM   #14
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Carefully plot the course on the computer being careful to insert the way points far enough away from submerged objects and the ground. .1 NM is enough. Transfer the course to the GPS. After departing the dock tie the autopilot and GPS. Sit back and enjoy the ride.

The farthest open water I've done is 90 miles. At 18 kts if the GPS fails, holding the current heading will get me within sight of my destination. Just hope I didn't get set in the wrong direction enough to run aground. On open water legs of that distance I always carry a battery operated backup GPS. Plus cell phone and tablet Navionics GPS and charts. I do however carry paper charts but have not plotted courses or updated as we go along. That's kind of tough bouncing along at that speed.

A couple of years ago I would have probably criticized this approach. However as any professional pilot knows, we rely entirely on electronic navigation and positioning. No one backs up their position on paper charts, if even they have them. Besides if you tried navigating any other way and got off course by even 1 mile, you would quickly be called by ATC.

Electronic navigation is reliable and accurate and here to stay, regardless of the legal warning you get every time you start your chartplotter. Now submerged and uncharted objects are another matter.
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Old 12-16-2012, 09:56 AM   #15
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Cyclone said :

"Perhaps you misspelled the word "dead". It should be "ded-reckoning"."

My ancient Chapmans spells it Dead as do my other historical navigation references. Is this a political correct thing I have missed?
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Old 12-16-2012, 10:04 AM   #16
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I learned it is Ded which is short form for Deduced. That was of course, before written language
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Old 12-16-2012, 10:08 AM   #17
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Sun chaser. No, but what we do is to deduce our location based on known and assumed facts. Remember that it was a Dutchman who devised a means to measure speed and an Englishman who enabled us to measure time. Regardless of the spelling DR is the foundation to all navigation notwithstanding our closets of electrical aids. Bill
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Old 12-16-2012, 10:27 AM   #18
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A friend was once third mate on a brand new Great Lakes 1000 foot ore carrier. During sea trials they left port on Lake Erie for a 3 day test. After getting into the lake they discoved that there were no charts aboard. My friend, having come up from lunch, remembered that the placemats were decorated with a map of the Great Lakes. They spent 3 days plotting courses on placemats. Back then (1970's) it was pretty much basic piloting with not even Loran; just radar, radio direction finders, piloting, and ded reconing. On the Lakes it was sometimes called (usually as a derision by "blue water" sailors) "Lampost Navigation": sailing from one "Lampost" (lighthouse) to another.
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Old 12-16-2012, 10:48 AM   #19
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Back then (1970's) it was pretty much basic piloting with not even Loran; just radar, radio direction finders, piloting, and ded reconing..
I resemble that remark. When I started fishing off the coast of NC, we did it all by ded reckoning We only had a flashing depth sounder with a paper chart recorder. We may not have known exactly where we were, but we knew where we weren't. Then I got an RDF to home in on the AM radio station on Radio Island behind Beaufort inlet. Then we got a military surplus Loran A that was single track, and had to be tuned in with an oscilliscope. Then there was a transition to Loran C. I had a weather proof chart with Loran A on one side and Loran C lines on the other. All our fishing spots were marked on both. The it was possible to know what the various guys were talking about on the radio whether it was A or C. Then GPS. The differential GPS. Then WAAS GPS. Then the best thing of all the chart plotter. Then it was dressed up with radar overlay, routes, etc. Today it is easier than ever.

Guess what. We still run paper charts in parallel with our Chart plotter. We still plot on paper our location hourly. Habit? Probably. Security? Definitely.
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Old 12-16-2012, 10:54 AM   #20
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.......... On the Lakes it was sometimes called (usually as a derision by "blue water" sailors) "Lampost Navigation": sailing from one "Lampost" (lighthouse) to another.
In the Gulf of Mexico, we call it Coon-ass Navigation. All of the oil and gas platforms have large signs giving the Oil Field and Block No. and supposedly Cajun (Coon-asses) fisherman and the older oil field captians navigated from oil field to oil field that way.
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