Actually, proper dead reckoning is a very important navigation skill and very worth learning. When GPS fails (out of power or somesuch), it's too cloudy to use the stars, knowing how to use dead reckoning can be your saviour.
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Actually, proper dead reckoning is a very important navigation skill and very worth learning. When GPS fails (out of power or somesuch), it's too cloudy to use the stars, knowing how to use dead reckoning can be your saviour.
Too right! Much, much underused skill.
The dutch have a version of this using a barge pole - the pole is marked in meters, you stand forward of the leeboards and 'cartwheel' it, with enough pole dipping below the water that you'll touch bottom if it's getting too shallow. They use this to navigate through the ever-changing, snaking channels off their coast. Very exciting doing this on a 30ton barge sailing at 8knots or so.
Agree, but only of use in non-tidal areas. Otherwise it has to be EP (estimated positioning). Astro navigation is an art, not easily mastered. Terrestrial navigation is much more user friendly and accurate for the average boater.
I'm not sure why. Taking into account tidal flow, leeway due to wind, speed over water, the difference between heading and direction of motion are just all part of dead reckoning. A good navigator constantly tracks these and confirms estimated position against other techniques frequently.
No it isn't. Just because some wimps don't use it fully, doesn't mean it can't be used properly.
It is, and I have clearly demonstrated on how your definition is incorrect.
I come at this subject as a qualified navigator, I spent three glorious years studying the subject and the definition of DR is chapter 1 stuff. You may choose to ignore the definition and make up your own version, but opinion does not trump fact...
I come at this subject as a qualified navigator, I spent three glorious years studying the subject and the definition of DR is chapter 1 stuff. You may choose to ignore the definition and make up your own version, but opinion does not trump fact...
No, you're understanding of DR is way out. Back to the books for you mrcharly
Oh no; Mrcharly nailed it dead on. The problem with it is that for it to be accurate you have to know what those tides, wind, etc. are. It takes an awful lot of experience to read and interpret them without instruments (more so than is within my ability)
And I come at this subject with minor seaborne navigational skills.
Dead Reckoning Definition (according to the Coast Guard's official definition)
"Definition:
Dead reckoning is used in marine navigation to determine the boat's approximate position using course and distance traveled without correcting for factors such as wind, sea conditions and current."
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My aplologies Qwerty. I misread that the first several times. It does indeed say "....without correcting for wind, sea conditions and current." It would appear you are correct.
Yeah - but like I said, you don't *have* to let that definition restrict you. Perfectly correct to take into account currents etc.
Just how do you do navigation without GPS or sight of landmarks and stars?
Just how do you do navigation without GPS or sight of landmarks and stars?
True. It just seemed so intuitive to allow for outside forces that I was taking it for granted. But qwerty's correct in saying that technically isn't true dead reckoning.
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The OP's asking about a first boat for a beginner. Realistically they should avoid those situations unless with a more experienced boater. To be perfectly honest, we still haven't heard if said interest is in sea boating or paddling around a smaller body of water (a bay, a medium loch/lake, etc. where no spot is really out of sight from the shore)
We're probably getting way ahead of a realistic starting point.
Actually you have to let that definition restrict you. If you are talking to another navigator the term DR means something specific to her. As does EP, and Assumed Position. It's the language of the "trade".
Marine navigation is really the sum of a whole bunch of estimates. Course steered: (unless you are in a large vessel) is the helmsman's guess at the average heading he has been able to maintain during his watch, particularly if there's any wobbly sea state. The heading can easily vary over 20 degrees. Then allow for compass deviation, which varies according to the vessel's heading. Distance run is down to the accuracy of the log, which can stop or slow with fouling to the impeller. Leeway: an estimate of the off-course push to the vessel that the wind has on it. Tidal set is another approximation; there are tidal atlases that show the speed and direction of the tidal flow at springs and neaps. Interpolate for your current state and then figure if the strong winds over the last day or so will increase or decrease the rate. Plot all those and you've got an EP, an estimated position.
Even if you get a fix, three points or more recommended, you still end up with a triangle within which you are likely located.
And, of course, by the time you have worked all the above out you aren't there any more as your vessel has been continuing merrily on its way, helped or hindered by leeway and the tide or ocean currents.
Navigation is the art of knowing that you are not where you think you are.
Without GPS there should be a compass and charts anyway but in a blinding fog the answer is "with difficulty". Listen for surf, take soundings, ring a bell, anchor?
"Those who go to sea for gain,
Are all a little bit insane.
But those who go to sea for pleasure,
Are certifiable by measure!"
Are all a little bit insane.
But those who go to sea for pleasure,
Are certifiable by measure!"
On a similar theme
Here lies the body of William Jay,
Who died maintaining his right of way.
He was right, dead right, as he sailed along,
But he's just as dead as if he were wrong.
Here lies the body of William Jay,
Who died maintaining his right of way.
He was right, dead right, as he sailed along,
But he's just as dead as if he were wrong.
Or as the fighter pilots like to say, "You ain't never been lost until you've been lost at mach 2.
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