Are paper charts as a backup still necessary?

[Ip485]

Furthermore I have never in my life been on a ship with no paper charts. If you mean tugs, ferries, oilfield vessels, etc then you may be partly right, but no commercial deep sea ship operates without paper charts.

I dont doubt the veracity.


I am never the less surprised given that aviators do not require the carriage of paper charts (and most dont carry them) while this trend is not taking place in shipping. If nothing else for commercial ops there is a huge cost saving in eliminating paper, which is usually the driving force if safety is not compromised.

[sailingharry]

Originally Posted by GrowleyMonster

Sorry, but the magnetic compass rose will still not necessarily be in agreement with your compass due to deviation. As a professional you ARE aware of this, right? It should be a given that in order to set a course to steer, you will still have to convert back and forth between either PSC and Magnetic, or PSC and True. So, may as well use true on the chart, and calculate the compass heading to steer from True. This allows you to reference the L/L grid with a protractor, too. And anyway, your azimuths will need conversion anyway. And if you do a compass check on a range, it will be in True. Honestly, the only thing in the world that is actually accurately in magnetic is a perfect magnetic compass far away from any wires or electricity or ferrous metals or any magnetic or electrical influence other than the earth's magnetic field. That leaves out pretty much any cruising boats compass, which even if adjusted and compensated can go out of adjustment with little more than a sneeze, at least figuratively.

Yes, I do know the theory of Deviation. Frankly, I've never been exposed to it in real life. I'm sure the Navy ship I served on had a deviation card, but we lived 100% on gyro, so never used it. I've never been on a pleasure boat with a deviation card, the best I've ever seen is well used compensation magnets. But, if you are used to doing the math as a routine on a commercial ship (no gyro?), and have a deviation table, then I guess it isn't a big deal. Of course, when you are done with the math, you are using magnetic for steering, autopilot, bearing shots, etc, right?



It is a big argument for paper charts -- if your GPS gives you true, you go look up Variation, then Deviation -- that's not easy using GPS! Much easier on a paper chart at a proper chart table.



But I still wonder how many "professional navigators" on vessels without a gyro use True as a "standar"

[GrowleyMonster]

There is always a gyrocompass. There is also always a magnetic compass, and if the gyro goes out, the AB on watch hand steers by the magnetic. After every course change when steering by gyro whether in hand or on the mike, he reports the magnetic heading to the mate on watch so he can calculate gyro error.

[SeanPatrick]

Russia blocked GPS data during NATO exercises: Norway


Full story here.

[seadago]

Originally Posted by SeanPatrick

Russia blocked GPS data during NATO exercises: Norway


Full story here.

Well, in the context of this thread, I would then avoid sailing in the north of Norway during NATO exercises, with or without paper charts.

[SeanPatrick]

That's all well and good as long as you don't happen to already be sailing in north Norway ... or anywhere near there.



Of course, the purpose of my post was to point out that GPS signals can be and are interfered with. Just because this time it didn't happen to be where you are doesn't mean it won't in the future. And without advance notice (which I kind of doubt a malicious actor would give), you might not even know it's happening until some time later.



The odds of this happening may be extremely low. All I'm saying is: it's possible.

[roland stockham]

Lots of talk here about lightening strikes, GPS failures and other exotic stuff but for me it is much simpler. The most common breakdown in ALL vehicles is electrical failure. Add salt water and it gets much worse. Could be charging system, batteries or wiring but the most likely reason to find yourself without a plotter is no power. I agree (and carry) a backup tablet with a separate power cell but they are fragile beasts so not 100%. The core wiring and batteries are rearly backed up even once even if the charging setup is. So basic safety suggests being able to run with no, or at least minimal power.

[wingssail]

Originally Posted by SeanPatrick

The odds of this happening may be extremely low. All I'm saying is: it's possible.

It's all a matter of each skipper's personal comfort level, and what they want to spend their time doing while on passage.

Personally I don't choose to spend a lot of time plotting positions and courses on paper, to say nothing of the expense and space used by paper charts, just to be prepared for a really rather remote possibility. I'd rather be sailing, fishing, lounging in the cockpit with my crew.

But if that's what you like doing, and you really like the level of comfort you get from having that level of preparation, then I say, go for it.

[seadago]

Originally Posted by SeanPatrick

The odds of this happening may be extremely low. All I'm saying is: it's possible.

Of course, it is within the realm of possibility. I'm not disputing the pertinence of your post Sean.

The general tone of these discussions ( i.e. astral navigation vs. any other electronic means of navigation) just seems to become ideological very quickly. Most of us in this forum are amateur or sport seamen, not pros, and not bound by methodological constrictions which apply to military or commercial shipping. It would seem logical therefore that we should have a mostly pragmatic approach to figuring out where we are at sea. Doesn't seem to be the case though.

Satellite positioning can fail, of course, for whatever reason. The question is: is astral navigation an operationally viable alternative for us?

If I am in the north of Norway, and GPS fails, for whatever reason, what is the likelihood that I could maintain a consistent and reasonably accurate position by astral navigation alone? Even if I was as good with a sextant in my hand as James Cook and Horatio Hornblower put together?

I've never been in the north of Norway, but I've been in the Southern Ocean, in Gough Island and the South Shetland islands in the summer. In neither occasion did I ever see the sun disk during the day, or the moon at night, for a week. I was on big modern ships both times and, thank goodness, navigating was the job of professionals. But if the weather is in any way comparable in both places, a sextant would have been utterly useless both times. Might as well rely on DR alone to estimate my position.

This is only my opinion, but if I am navigating unfamiliar waters, any waters, and my GPS fails, I would put immediately into the first port I can safely get to, and get the GPS fixed, before continuing my passage. I would not carry on irrespective, relying on astral navigation. No matter how good at it I may be.

I suspect most of us here would do likewise.

[noelex 77]

Failure, or worse corruption, of the GPS signal is a problem both for those using paper or electronic charts.

The significance of the problem primarily depends on the skills of the navigator and the situation.

There is common belief that if a loss of the GPS signal occurs, the chartplotter no longer works. This is not accurate. The charts on the chartplotter still work fine if the GPS signal is jammed. The boat with electronic charts (for example a chartplotter) is really no different from the boat with paper charts that has suffered from the same loss of a GPS fix.

If loss of the GPS signal occurs, paper charts are often easier to use than electronic charts on a charplotter, but the difference is not enormous, and there is no reason why the boat with only a chartplotter should not be able to navigate successfully.

In short, the remote risk of the loss of the GPS signal is no reason why paper charts need to be carried.

[MartinR]

Originally Posted by noelex 77

In short, the remote risk of the loss of the GPS signal is no reason why paper charts need to be carried.

I agree completely!

[SeanPatrick]

Originally Posted by seadago

This is only my opinion, but if I am navigating unfamiliar waters, any waters, and my GPS fails, I would put immediately into the first port I can safely get to, and get the GPS fixed, before continuing my passage. I would not carry on irrespective, relying on astral navigation. No matter how good at it I may be.

I agree. Relying on celestial or DR alone today would be quite foolish.

Originally Posted by seadago

Might as well rely on DR alone to estimate my position.

That's probably what one would have to do in the case of GPS failure. However, cross-checking position with celestial (when available) may indicate a potential problem with GPS earlier - allowing for a more accurate DR. And as noelex 77 points out:

Originally Posted by noelex 77

The charts on the chartplotter still work fine if the GPS signal is jammed. The boat with electronic charts (for example a chartplotter) is really no different from the boat with paper charts that has suffered from the same loss of a GPS fix.

I don't know about all chart plotting systems, but OpenCPN allows for the plotting of celestial observations right on the electronic chart. No need to stop using it because of GPS failure. And it's quicker/easier than plotting one's position by hand.

[roland stockham]

[QUOTE=SeanPatrick;2762374]I agree. Relying on celestial or DR alone today would be quite foolish.


Really, all sailors before the current generation were foolish? When I learnt to sail GPS was not available for smaller boats. I belive it may have just come in for large ships but cost thousands.and I never saw one. Normal nav was by observation DR and celestial. People made passages and arrived where they expected.

[SeanPatrick]

Originally Posted by roland stockham

Really, all sailors before the current generation were foolish? When I learnt to sail GPS was not available for smaller boats.

Perhaps I should clarify:


Relying on celestial or DR alone today, when GPS is so readily available, would be quite foolish.


Of course if you didn't have it you couldn't use it. Don't get me wrong, I love celnav ... but why wouldn't you use a GPS when they're so ubiquitous?

[sailorboy1]

I'm impressed people are still "discussing" this.

I carry paper charts just for ease of looking at the "big picture", not out of any paranoia. If other don't want to what does it matter to the rest of us?