Paper Charts Now Unnecessary

[Rakuflames]

Originally Posted by Andrew Troup

Wolfenzee

thanks for that, I should have been clearer. I was talking about using a chartplotter (rather than a paper chart) to plot bearings and courses originating from human input, not from digital input.

That's not what they do. There may be a computer program that does it, I don't know.

[wolfenzee]

If a GPS says that (due to conditons) it is accurate to 30meters the computer will not draw a circle with a 30 meter radius (have seen as much as 245meters and no less than 5meters) but put your location in the center. Chart platter direction is based on the direction you are moving not the direction you are pointed otherwise current software could figure out the effect of the current, no piece of software can figure in the effect of the wind because of the variables involved a person can only do it with an in depth knowledge of and experience w/his boat.
A friend of mine ended up on a reef because he was relying solely on what his GPS told him

[wolfenzee]

Originally Posted by Andrew Troup

Wolfenzee

thanks for that, I should have been clearer. I was talking about using a chartplotter (rather than a paper chart) to plot bearings and courses originating from human input, not from digital input.

If all input is manual than the only differance is the fornat of display

[Ex-Calif]

Originally Posted by wolfenzee

If a GPS says that (due to conditons) it is accurate to 30meters the computer will not draw a circle with a 30 meter radius (have seen as much as 245meters and no less than 5meters) but put your location in the center. Chart platter direction is based on the direction you are moving not the direction you are pointed otherwise current software could figure out the effect of the current, no piece of software can figure in the effect of the wind because of the variables involved a person can only do it with an in depth knowledge of and experience w/his boat.
A friend of mine ended up on a reef because he was relying solely on what his GPS told him

Not sure what you mean by no computer can figure out the effectis of wind? If the data can be collected the computer can calculate it. Faster and with higher accuracy than a human.

[wolfenzee]

Originally Posted by Ex-Calif

Not sure what you mean by no computer can figure out the effectis of wind? If the data can be collected the computer can calculate it. Faster and with higher accuracy than a human.

to figure the effects of the wind you have to factor in the characteristics of the hull, rig. sails, waves action, wind speed and angle as they apply to your individual boat....these can only be know through experience with that particular boat

[Ex-Calif]

Originally Posted by wolfenzee

to figure the effects of the wind you have to factor in the characteristics of the hull, rig. sails, waves action, wind speed and angle as they apply to your individual boat....these can only be know through experience with that particular boat

I don't disagree but how is this used in navigation?

If I am reading right there is a question that says basically, I am here, in the future I will be in this cirlce of error based on wind, waves, nav error etc. Is the wind error what we are saying the computer cannot predict or calculate?

Because if you can reduce the effects to mathematical constants or even a combined factor one should be able to...

[wolfenzee]

Originally Posted by Ex-Calif

I don't disagree but how is this used in navigation?

If I am reading right there is a question that says basically, I am here, in the future I will be in this cirlce of error based on wind, waves, nav error etc. Is the wind error what we are saying the computer cannot predict or calculate?
because the plotterr does not use magnetic compass inut we are talk
Because if you can reducing about urrent and wnd errice the effects to mathematical constants or even a combined factor one should be able to...

Dead reckoning is figured by taking into account last known position, compass heading, speed, effects of wind and current to come up with your actual bearing and new position.
Because the computer does not use magnetic input we are talking about current and wind error...because the computer figures bearing from cumulative GPS fixes the error doesn't matter

[Andrew Troup]

Originally Posted by wolfenzee

If all input is manual than the only differance is the fornat of display

Well, yes, that's the point of my question. How much can I draw, at my discretion, and how easily?

If I'm using a paper chart, and I read in the logbook, after a rough night watch, that crewman "X" reckons he's been trying for 185 but only made good 192, I might draw two lines on the chart, one at 190 and one at 200. (This may include an allowance for leeway based on conditions and past experience). I might shade between the two lines to make it clear what they represent, especially if sharing the nav duties with another.

(If it was crew "Y", they might just log that they always make good the course ordered. I might however know from experience they don't do even as well as "X", at least, not on this trip.... in which case I'd draw a wider wedge after their watch. I'm not needing any help from the ship's computer on this, because as far as I know, the computer doesn't know about Y's marriage difficulties )

If there's a current, I'll do the vector addition to one of the lines, but then slew them both.

Then when we cross an ocean ridge at a suitable angle and the soundings give me a rough distance along that wedge, I draw a rough box or ellipse on the chart to cover the whole range of our probable positions. Or I might get a bearing on a distant lighthouse, which I know might be plus or minus 3 degrees out: similar sort of process (a wedge of two lines crossing the first wedge, and the ability to selectively shade or somehow indicate the resulting position box)

If I don't get a better, tighter fix, the worst position in that moving, growing box, in respect of any danger, is where I will assume us to be when planning when to come onto a new course to clear that danger.

Now, earlier in this thread the assertion was made on several occasions that this type of manual-input navigation was easier and better with a chartplotter than with a paper chart.

If that was not the case, then this thread becomes somewhat pointless, because it becomes a subtopic of a higher level "Should we place sole reliance on GPS and forget about navigating and pilotage?" topic.

If the answer to that question is "No" (and for me it is) and the answer to my question about plotting evolving uncertainty of positions on a chartplotter is "No can do", then for me the answer to the question "Are paper charts now unnecessary has to be a resounding "No".

[wolfenzee]

Here, as with all threads...to each their own, I just hope people listen carefully enough to what other people are saying to be able to complement their own opinions and/or practices.

[Lagoon4us]

Our system onboard is a E120 Raymarine using Navionics Gold Charting.

We are considering getting a program to run on our MacBookPro that can connect to the above system. We would want to install a stand alone aerial to allow this to run separately once info has been exchanged. There is a Sealink USB Serial Adaptor wired into the Raymarine system also.

One such system i've found is PC Plotter, any advice or suggestions?

Is my thinking correct?

Cheers Frank

[carstenb]

Andrew

Your methods are inpeccable and worthy of imitation. However most "sailors" today simly look at their chartplotter and say "we're here". If they only have a HH GPS they they simply plot the point the GPS tells them on the chart.

Many coastal sailor have no working knowledge of concepts like current, windage etc. The chartplotter shows actual course over ground and so they don't need to do anything else. In a pinch they move the cursor to the harbour they are trying to reach, the plotter tells them the bearing and then they steer that. Every now and then they repeat the excercise and get a new bearing. That will nullify the effects of windage and current.

And yes, I do know "sailors"who sail like that.

[noelex 77]

Originally Posted by Andrew Troup

Now, earlier in this thread the assertion was made on several occasions that this type of manual-input navigation was easier and better with a chartplotter than with a paper chart.
.

For full time "traditional" navigation like this I would much prefer paper charts.

However there is no great difficulty doing what you want on most electronic charting systems. Some of the techniques will be different, shading for example is not possible but there are other ways of doing this such as using different colours etc that are not possible on paper chart.
If you have a particular requirements the talented people in the open CPN forum will write a program so it will do just what you want.


On comment I would make is I think it's much better to use the technology, for example using a GPS position to determine what the true COG has been for the watch will help your helmsmen in the future to estimate more accurately what course they have been achieving, even if they have marriage difficulties

[Ex-Calif]

Originally Posted by Andrew Troup

.

Now, earlier in this thread the assertion was made on several occasions that this type of manual-input navigation was easier and better with a chartplotter than with a paper chart.

If that was not the case, then this thread becomes somewhat pointless, because it becomes a subtopic of a higher level "Should we place sole reliance on GPS and forget about navigating and pilotage?" topic.
".

If plotter is failed all that makes sense.

if plotter is not failed you know exactly where you are at the start of every watch.

And my nav program (navionics) has a projection line extending out in front of the boat. You can put the projection line on a mark and forget all about set drift etc. because, who cares?

In addition we've discussed inn the past, with boat speed, SOG, trua and apparent wind - lots things can be calculated.

Should be no disagreement that one must know one's own boat to understand what the set will be in various conditions. Useful when ded reckoning.

[Andrew Troup]

n77: Thanks for taking the time to understand what I was asking, and your answer is encouraging.

Is this true for most standalone chartplotters? (I've only used systems running on a laptop, and certainly they could do some of what I wanted, but I found it a bit laborious...

(incidentally, some people do use colour pencils for paper chart work -- I prefer not to, but only because it's harder to erase - electronic linework has the opposite problem: it's too easy to erase!)

Originally Posted by noelex 77

..... using a GPS position to determine what the true COG has been for the watch will help your helmsmen in the future to estimate more accurately what course they have been achieving, even if they have marriage difficulties

Hmmm... therein, it seems to me, lies a wee problem in man management.

Why would such a person strive to perfect their estimation of CMG , knowing GPS was on the case, and could be pretty much relied on to demonstrate their estimate to be inadequate.

Lets face it, it's not what a guy with marital problems needs. He already knows exactly how inadequate he is

In a motivational sense, it's like requiring the crew to bark when they know there's a genuine dinkum dog on board.

Being serious for a moment, I find it disappointing how hard it is to use GPS as a sort of talisman/guardian angel.

In an ideal world, I'd like to navigate the human way as well as I knew how, then from time to time use GPS the way a schoolkid uses a teacher, to mark their work.

The aim being to improve those skills, ending up with the best of both worlds: maximum benefit from GPS, with minimum reliance.

However that's a test of character I only rarely manage to pass.

I'd almost rather keep a handheld GPS sealed away in the snatch kit, to be resorted to in only in dire need.

I say this because not having it on tap would help me keep up skills which I find add a great deal to my satisfaction, and whose continuous exercise helps cue me in to the nuances of the interplay between conditions and progress.

[noelex 77]

You could assign the the crew member with the marital problems to monitor the GPS. He could look over your shoulder while you doing the DR plot, and say "so you you think we are, that's interesting" Think of the boost to his self esteem

If you don't want anyone to use the GPS this may be useful.
http://www.icselectronics.co.uk/site...e/NAV4plus.pdf

It's a navtex receiver but it will print out on paper a position from a GPS every hour.
If the GPS fails there is still a hard paper copy of the last position, without any human intervention.

Personally I prefer the opposite approach I always compare my DR and GPS positions. I find I learn much more that way- maybe the leeway is a bit less than you allowed for- perhaps the log slightly under reads on starboard tack. This sort of information makes you a more accurate navigator in the future.