Paper Charts Now Unnecessary

[noelex 77]

Originally Posted by Andrew Troup

My estimation of inaccuracy does not itself have to be accurate, provided it's suitably conservative.

I don't know where I am, but I am sure of where I am not.

This is a good principal of DR navigation.

I am still not clear why, other than a an exercise, or practice, why you would not turn on the GPS and find ( within 20m or so) where you are?

[Andrew Troup]

Originally Posted by noelex 77

I don't know where I am, but I am sure of where I am not

That's not fair.

So few words, so much meaning!

Originally Posted by 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

Double not fair. You've clearly forgotten more about man management than I will ever know. Kudos !

If you're thinking of applying for a top post in the UN, I'm happy to be a referee. But it would be a great loss to the forum....

[Andrew Troup]

Originally Posted by noelex 77

I don't know where I am, but I am sure of where I am not.

This is a good principal of DR navigation.

I am still not clear why, other than a an exercise, or practice, why you would not turn on the GPS and find ( within 20m or so) where you are?

Because I'm a lazy, flawed, human being. If the GPS is easily invoked, why would I be doing all this work?

It's a test of character which I routinely fail. I'm not sure I'm alone in this....

In the satnav era, there was still sufficient (demonstrable) unreliability to push me into doing the work to 'keep the technology honest"

GPS is almost infalllible, and to me that perceived infallibility entrains a paradoxical hidden cost.

Inviting gods on board turns out not to make us more godlike, but less.

(ON EDIT I shouldn't say "us" , I should say "me")

[Andrew Troup]

Perhaps someone should make a special GPS for people like me. One with no display, just a personality chip and a voice synthesizer.

"Near enough, champ"

"Try again, grasshopper"

"Woop Woop Woop PULL UP PULL UP !!!"

[kiwitrucker]

In a lot of these post you guys have been using words and phrases, that myself as a newbie, have no idea what you mean. Reading between the lines I am thinking
1 It is a lot of what the skipper understands.
2 It is a lot of what the skipper is comfortable with.
3 If using only electronics have at least one independent back up.
4 have paper charts aboard for emergences.
Am I reading this correctly?

[Rakuflames]

Originally Posted by wolfenzee

I am a poor sailor and can't afford more than Nobeltec 6.5 on an laptop.


This also works for developing your celestial navigation skills or for that matter any form of "analog" navigation.....functional electronic navigation can be very helpful when learning to navigate when the electronics aren't functional.

Exactly!

[wolfenzee]

Originally Posted by Andrew Troup

Because I'm a lazy, flawed, human being. If the GPS is easily invoked, why would I be doing all this work?

It's a test of character which I routinely fail. I'm not sure I'm alone in this....

In the satnav era, there was still sufficient (demonstrable) unreliability to push me into doing the work to 'keep the technology honest"

GPS is almost infalllible, and to me that perceived infallibility entrains a paradoxical hidden cost.

Inviting gods on board turns out not to make us more godlike, but less.

(ON EDIT I shouldn't say "us" , I should say "me")

The key word is almost, electronics are almost infallible and extremely precise.....but the fact that they are not entirely infallible or precise ended a friend of mine up on a reef, he was entering a tight harbor using a GPS. the coral was closer than the variance in the GPS. Electronics are not perfect and should not be treated as such.

[Rakuflames]

Originally Posted by wolfenzee

The key word is almost, electronics are almost infallible and extremely precise.....but the fact that they are not entirely infallible or precise ended a friend of mine up on a reef, he was entering a tight harbor using a GPS. the coral was closer than the variance in the GPS. Electronics are not perfect and should not be treated as such.

Coral grows ... and sand shifts. Makes a great case for getting on the radio and gathering some local knowledge.

[Rakuflames]

Originally Posted by kiwitrucker

In a lot of these post you guys have been using words and phrases, that myself as a newbie, have no idea what you mean. Reading between the lines I am thinking
1 It is a lot of what the skipper understands.
2 It is a lot of what the skipper is comfortable with.
3 If using only electronics have at least one independent back up.
4 have paper charts aboard for emergences.
Am I reading this correctly?

Gotta have a backup. Went on a club cruise on someone else's boat when I first started sailing.

His chartplotter had a black screen. It was coming on but couldn't be read. He used DR to find the sneaky little channel we were going into. He looked around and saw ALL the other club boats in the wrong place. Then they started running aground. They were all following one boat that had the wrong coordinates for the waypoint in his chartplotter.

The next morning he figured out how to brighten his screen which was really useful because this expert (truly) mariner had forgotten to secure the bitter end of his new anchor. But when the chartplotter turned on, he had had "tracking" on, and it showed very clearly where the anchor should be.

He went around in a circle with his dinghy around the area where the anchor was as indicated by the chartplotter with a grapnell and grabbed it on the first try.

[wolfenzee]

Originally Posted by Rakuflames

Coral grows ... and sand shifts. Makes a great case for getting on the radio and gathering some local knowledge.

This wasn't a matter of coral growth, just not taking into consideration GPS error.

[Rakuflames]

Originally Posted by wolfenzee

This wasn't a matter of coral growth, just not taking into consideration GPS error.

What GPS error? Most (can't speak about computer or tablet-based programs, although I just ordered a tablet and will be learning about it shortly) -- my Garmin seems to always match my paper chart.

Just sailed up the Manatee River a couple of days ago, the same river that banged my boat and bent my rudder in rough water five months ago ...

The pilings and channel markers where it happened are just GONE now. Local knowledge told us to go south of where they are on the chartplotter and chart -- point being, both were wrong. That change was due to shifting bottom in the channel.

Did this fellow's chart have different information than his chart plotter? I still get on the radio and look for local knowledge coming into a new channel. Now I think I'll do it for "known" channels too, as I've been up this river multiple times before ...

[wolfenzee]

GPSs say they are accurate to xmeteres, conditions and how many satellites are found changes this

[Ex-Calif]

Originally Posted by Rakuflames

Gotta have a backup. Went on a club cruise on someone else's boat when I first started sailing.

His chartplotter had a black screen. It was coming on but couldn't be read. He used DR to find the sneaky little channel we were going into. He looked around and saw ALL the other club boats in the wrong place. Then they started running aground. They were all following one boat that had the wrong coordinates for the waypoint in his chartplotter.

The next morning he figured out how to brighten his screen which was really useful because this expert (truly) mariner had forgotten to secure the bitter end of his new anchor. But when the chartplotter turned on, he had had "tracking" on, and it showed very clearly where the anchor should be.

He went around in a circle with his dinghy around the area where the anchor was as indicated by the chartplotter with a grapnell and grabbed it on the first try.

Gotta be careful here...

The one boat induced an error with a bad fix. you cant hang that o the gps.

The guy that was using DR was more likelynusing visual navigation. DR would indicate to me he plotteed a course considering current and leeway and followed the resulting mag heading. More likely he was navigating off landmarks - visually.

And to Andrew. For me "set" includes current and wind leeway effects. How far did the boat get set down current and downwind.

I am not proposing reduce everything to numbers, just pointing out one can. You prefer to provide an educated guess on set. If I know that from past experience I get set 1 mile every 5 miles in a 15 knot reach it is simple to calculate CTS to offset the set. Add the current effect (kts X time) and you can calculate the course correction to add or subtract for set.

I encourage folks to practice this often. I see too many skipers sailing a french curve cuz they dont understand set.

Of course the gps does this for you by providing constantly updated CTS.

[Cookiesa]

I love when navigating tight channels etc is brought up and the enevitable story of a bad "gps" location causing someone to run aground.

Bet you the gps is more accurate and the position updated much quicker than anyone doing DR could do it, considering the data is the same, if the location of the reef etc is wrong or marks missing as already discussed then the odds are someone is going to come unstuck. Most sailers I know, regardless of the method of naviagtion they use do as already mentioned, ask for local knowledge, watch for tell tale signs on the water of impending danger and keep a good look out.

Very few would be marking their charts in this situation but rather concentrating on keeping the vessel safe.

[wolfenzee]

The purpose of DR is either to give you some idea where you are until you can get a fix or get you close enough to the coast to be able to recognize landmarks and/or nav markers