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Our Tyme · 24-09-2016, 08:26

I just remembered a point to ponder. The navy stopped teaching celestial a while back. But now I hear they are teaching officers hands on and QMs at least theory. Hmmmmmmm

Ken

S/V Alchemy · 24-09-2016, 08:30

Quote:

Originally Posted by jackdale

I prefer paper for coastal navigation.

I use GPS for bluewater. But I can get a noon sight and a sun-run-sun sight for all else fails.

Playing the sextant and tables is a great way to while away a very boring offshore watch. It also puts me back in touch with the universe.

Exactly. Analog means of navigation also provide a situational awareness far more difficult to achieve (the boat is analog, also) by watching a representation of a boat in the form of a little black triangle on a screen.

Less understood these days are the ways to use a sextant to determine distance off (turn in on its side and measure the angles to two shore points) or distance off by noting sea level to a mast on a cliff, for instance. A sextant's role in navigation is broader than just noon sights and almanacs suggest.

exMaggieDrum · 24-09-2016, 08:36

Quote:

Originally Posted by knockabout

it's a good practice out of sight of land to turn off the electronics and stay on course using compass / watching the angles of the swells, chop etc / pick out a star in relation to your course / steer on that until it disappears, find another one / I do get growled at when the sleep timer goes off and the first mate who likes the gadgets has to boot it all back up again / she doesn't like having a star pointed out and being told to keep the chop slightly on the starboard side

I think we all need to be planning for the inevitable: the north and south magnetic poles are overdue for swapping. Me thinks that will play havoc on the navigation by compass mode. Perhaps someone should be working on an app for our smartphones to make the appropriate adjustments to our compass readings.

Just speaking for myself (of course) but I can't imagine life without a GPS. If I lose mine I am going to just pray that I soon end up on a reef with crashing surf to put me out of my misery.

**TrentePieds** · 24-09-2016, 08:59

Under most pilotage conditions it doesn't really matter if you know with PRECISION where you are. You do need to know with "reasonable" accuracy where you are, but knowing within a mile is usually good enuff.

You have but two objectives: 1) you must be able to avoid IMMEDIATE dangers, such a floating debris and other shipping. 2) you must be able to make landfall "somewhere near" you destination even if that destination is an "alternative" one possibly chosen under stress of weather while iunderway.

For the former, "aids to navigation", such as GPS, don't help you much A good lookout does. GPS may indeed be a detriment to keeping the required lookout if you are single-handing or have a green crew. At my cruising speed I move ten feet a second. Ergo it takes three seconds to move a boat length. In three seconds I can alter course 90º. So that's that problem outta the way.

For the latter, my DR, including CC steered, gets committed to paper - chart AND log - every fifteen minutes, not because I particularly need it, but because passage making is intrinsically so boring that I need something to keep me amused. I log the CC rather than True, cos True just introduces spurious accuracy. I don't see that in a tubby, fin keeled, spade ruddered boat you can hold a course for more than a few second at a time, so your track is gonna wander about, and converting to True has no practical value.

In consequence of plotting every fifteen minutes I'm rarely more than a mile from from a plotted DR position (or a fix) and if I forget what course I was steering prior to a course change, the course steered less than 15 minutes ago is both immaterial and documented.

We are talking pilotage. It's rare that I can't get a bearing on a landmark. My binoculars have a bearing compass in the reticle, of course, and, once again, a bearing so obtained is "close enuff" to give me an idea of how far my DR is off so I can compensate accordingly. The difference twixt DR position and fix gives me a good idea of the set, which can be strong here, 2 knots being frequent in the Straits of Georgia. That means half a mile in fifteen minutes.

When the fog comes down, or the "Wet Coast" is earning its name, being set a half mile abeam can be a pain.

And this is where the GPS finally comes in: The one in my car is a retrofit. Detachable. I take it aboard. I set it so all I get from it is coordinates. I plot the coordinates on the chart to get a "fix" and correct my DR.

No "science" to any of it. Just common sense. So far, so good :-)

TrentePieds

**Bulawayo** · 24-09-2016, 09:25

Why would a lightning strike take out my watch, Stumble? I guess you are referring to electronic watches? I use an automatic - all mechanical. However, its possible that calculators shall be unusable and that shall stuff many people as they may not be able to do the maths. I still have my old school slide rule! Similarly my ships clock is mechanical - wind up every 7 days. I still carry a massive pile of BA charts, despite investing in Sat Nav and later a chart plotter/GPS. We carry a sextant and Air Tables and once in a blue moon actually break them out; but less and less. Unfortunately, my Tamaya nav computer programming has 'expired' around ten year ago - be interested if anyone knows how to get it updated?
Regardless, total electrical failure is a possibility - and that also means being unable to start the engine(s) and dependent upon your systems the loss of your compass. There are of course basic ways to get around these issues. The situation of no electricity is discussed in a book; 'One Second After' after an EMP device is used.

Quote:

Originally Posted by Stumble

The worst case scenario in a severe solar storm is that GPS accuracy will degrade from 1m to 10m. Frankly, no even in the worst solar storms worrying about the positional accuracy of GPS isn't a real thing. Space Weather and GPS Systems | NOAA / NWS Space Weather Prediction Center

As for getting hit by lightning and loosing all your GPS chips...Sure it could happen, but any lightning strike that powerful is also going to take out your watch, so how would you take a site anyway?

But of course you need to know how to navigate, you just need to learn how to navigate with GPS.

jackdale · 24-09-2016, 09:26

Quote:

Originally Posted by lordgeoff

I could not think of anything more terrifying than knowing all the boats sharing the water with me were being navigated by people with sextants, watches and paper charts....

I could not think of anything more terrifying than knowing all the boats sharing the water with me were being navigated by people staring at chartplotters.

**TrentePieds** · 24-09-2016, 09:26

Quote: "...most people that know it rarely do it which means that the folks that don't know it don't even see it in passing and may not even be aware of it as a skill"

Quite right! I consider that we old-timers have a responsibility to make sure that these "retrograde" skills are not lost by a clueless generation now chomping at the bit to take over where we are leaving off.

It has amused me that MyBeloved, who cannot be "taught" in the formal sense cos she is a "left-over flower-child" who doesn't thrive in authoritarian environments, has been sneaking up behind me and figuring out what I've been doing. Now, after a coupla seasons of my NOT teaching her, but just answering questions asked, I find her saying off-handedly "Oh, I can do the plot". And so she can :-)

She doesn't have a clue about formal trigonometry, but she can still do "distance off". How does that work :-)??

She is, in keeping with so many of those who came of age when "The New Left" was at its zenith a mathophobe. Yet, provided I don't stick my oar in her water, she handles the TSD equation perfectly well without knowing anything about equations in a formal sense.

Electronic is nice, but it's the old skills that'll save your butt when the fit hits the shan!

TrentePieds

crabcake · 24-09-2016, 10:01

Quote:

Originally Posted by Stumble

The US Navy though has to be able to conduct operations in the event of all out war including the intentional destruction of hundreds of GPS sattelites. If there is a war involving the US, Europe, Russia, China, and Japan all shooting each other sattelites down I frankly will have other things on my mind.

You may recall two years or so ago, the Chinese launched two satellites, one was a "regular" sat, the other was a killer sat. They then blew up their regular sat. It was widely reported.

This was not lost on the U.S. Navy (military in general). Not only are sextants coming back, but the military who several years ago discontinued HF operations, is now bringing back HF as a backup for SAT coms.

Granted, HF does have limitations in severe solar disturbances. Fortunately, there aren't that many.

CaptChris376 · 24-09-2016, 10:29

Quote:

Originally Posted by SV DestinyAscen

For backup - a cheap mark 3 is more than sufficient. Noon sight isn't advanced navigation and I think all the conceivable GPS failures during passage basically means you're going to contingency mode and will not be needing much more than latitude to make to the nearest safe harbor to make repairs or wait out WWIII.

Good to know, thanks!

**Adelie** · 24-09-2016, 10:36

Quote:

Originally Posted by Our Tyme

. . .
Question, if hit by lightning is it like EMP or will unconnected devices be O.K.
. . .

It's as bad as an EMP. Unconnected devices have no garuntee of safety. The very high and rapidly rising and falling magnetic field can induce damaging currents even in very short conductors. The longer the conductor the greater the risk.

Because of the magnetic component I am uncertain whether a ferrous metal Faraday cage is better than one of aluminum.

A house is but a boat so poorly built and so firmly run aground you would never try to refloat it.

Stumble · 24-09-2016, 10:41

Quote:

Originally Posted by Our Tyme

I just remembered a point to ponder. The navy stopped teaching celestial a while back. But now I hear they are teaching officers hands on and QMs at least theory. Hmmmmmmm

Ken

The Navy brought back celestial because they need to operate in the event of a nuclear war or WWIII. Personally in the event of either of those occurring I will be doing something other than stressing about cruising the islands... Where you will likely be shot as a spy anyway.

Right now all major 'GPS' chips use at least the US and Russian sat nav systems, because Russian law requires all GPS chips sold there to use their system, so iPhones, iPads, androids, garmin, Raymarine, etc all started using dual system chips years ago.

The only two countries in the world withenoughsattelite killer missles to drop those systems are the US and Russia. So it would take an all out war between those two countries before GPS systems could even be credibly threatened.

In the next five year the Europoean, Chinese, and Indian systems will all be coming fully on line, and modern chips are already on the market that take advantage of the combined sattelite system, making a global threat to sattelite navigation almost unfathomably unlikely.

The USN Acadamyalso spends a good bit of time practicing how to respond to a chemical weapon attack. Do you carry gas masks and fully body suits, and time yourself getting into them?

rognvald · 24-09-2016, 12:01

Quote:

Originally Posted by lordgeoff

I could not think of anything more terrifying than knowing all the boats sharing the water with me were being navigated by people with sextants, watches and paper charts....

And the assumption is that they are incompetent? You apparently are unaware of the history of navigation for the last 600 years. I'm hoping your remarks were intended to be humorous. Good luck and safe sailing.

barnakiel · 24-09-2016, 12:42

Quote:

Originally Posted by Our Tyme

I just remembered a point to ponder. The navy stopped teaching celestial a while back. But now I hear they are teaching officers hands on and QMs at least theory. Hmmmmmmm

Ken

http://www.naval-technology.com/feat...large-4809513/

Meanwhile HM Navy re-introduced astro navigation to the cadet courses.

Horses for the courses. ;-)

b.

barnakiel · 24-09-2016, 12:49

I do not care if people around me use paper or electronics. You cannot tell this anyways by looking at a random boat approaching you on a collision course and taking no action.

From looking at why accidents happen, they all navigate fine all right, just a pity they spend all their sailing time down below watching TV and chatting on their smartphones, while the day outside is so nice and lovely. If only they popped up in the cockpit now and then, there could be far fewer crashes!

b.