Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 13-03-2009, 19:56   #91
Registered User

Join Date: Dec 2007
Location: Brisbane
Boat: deboated
Posts: 672
Quote:
Originally Posted by RBEmerson View Post
Where do you think the C-Map data comes from? It's the same data sources that drive the charts, if not the same basic artwork. Couple that with C-Map's slow update cycle (vs weekly updates for NOAA, and even those lag reality) and "having both on board" is, if anything, worse than nothing if you think C-Map is somehow more right than NOAA. Just because it's on an LCD display doesn't make it right.

And, of course, just because it's on a NOAA chart doesn't ensure 100% accuracy, either. There is room for healthy skepticism when it comes to charts, and navigation in general...
I think your missing the point and that is that everytime something is copied there is room for error.
__________________

__________________
meyermm is offline   Reply With Quote
Old 13-03-2009, 20:10   #92
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Quote:
And, of course, just because it's on a NOAA chart doesn't ensure 100% accuracy, either.
Having a title does not convey perfection. This idea that GPS is so accurate is not anything compared to locating everything accurate relative to everything else. One point is nothing. Charts don't come from one source. It's a blend of a lot of sources merged together so they fit. There is no way to tell what parts are very accurate and which are inaccurate. If it were that easy they would all be accurate. When you are out there at one spot and things don't match all bets are off. Most of the chart can be accurate but not everyplace. Relative accuracy is actually quite good. The process used by NOAA is as good as it gets and they don't have it perfect.
__________________

__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 13-03-2009, 20:47   #93
Registered User
 
RBEmerson's Avatar

Join Date: Jan 2008
Location: SE PA
Boat: Baba 35 - One With The Wind
Posts: 392
Quote:
Originally Posted by meyermm View Post
I think your missing the point and that is that everytime something is copied there is room for error.
Er, I didn't, albeit in different words, say that?
__________________
S/V One With The Wind
'85 Baba 35
"You and I may agree, but we could both be wrong."
RBEmerson is offline   Reply With Quote
Old 13-03-2009, 22:17   #94
Registered User

Join Date: Dec 2008
Location: South-western Pennsylvania
Boat: no boat, I'm a "landlocked" navigator
Posts: 87
Quote:
Originally Posted by RBEmerson View Post
Repeat after me... "We are all a battery failure away from the Age of Sail". Take a lightning hit and the boat goes dark, those paper charts are going to look very, very attractive. (True story: ) Walking up Thames St. in Newport, RI one summer evening, a couple asked us where Armchair Sailor (nautical bookstore) was and if it was still open. It seems their laptop and printer had died, they had no paper charts, and had to get back to New Jersey ASAP. Armchair Sailor was closed. Point made, I trust.

Understand we have two GPS receivers running on the boat and either can drive a latptop with a chart plotter program (Coastal Explorer). Still, we have paper charts on board and once out of home waters, we at least mark our location on the paper chart, updated about every 30 minutes (and often leave nav notes, courses, etc., too).

Finally, don't get trapped by "if it's electronic, it must be really right". "Garbage in, garbage out" still obtains as much as ever.
Re celestial navigation, I'm LANDLOCKED. Having said that, re electronics, and I used to work in engineering design and construction, where CAD had become all the rage, you absolutely would not believe some of the garbage I came upon while working as a drawing checker, checking piping drawings done with Auto Cad. The "cells" or was it "blocks", had been done by kids who were "computer operators", but unfortunately didn't know anything much about the hardware, pipe fittings, they were dealing with. The standard excuse ran as follows. If it came from the computer,it couldn't be wrong. In point of fact, not only could it be wrong, often it was. As the man offered, Garbage In Garbage Out.

Re Navigation, electronics are wonderful, so long as they work, but never forget the KISS Principle. Keep It Simple Stupid. Sextants do not need batteries.The late William F. Buckley, who I believe used electronics in navigation once said something about old fashioned virtues or being somewhat anacronistic, something like that. I believe he never sailed the ocean without a sextant, appropriate tables and a time piece of some sort.
__________________
alan2 is offline   Reply With Quote
Old 13-03-2009, 22:28   #95
Registered User

Join Date: Sep 2007
Location: Colombo
Posts: 1,059
Quote:
Originally Posted by Hampus View Post
I work with theses things.. For a living. You are plain out wrong here. Paper charts will not be illegal. Paper charts are constantly updated, just the same as electronic charts are. All electronic charts are based on exactly the same information as the paper charts, same readings and measurments. If the paperchart is wrong, so is the electronic chart and vice versa...
I am afraid that you are in for a surprise because MarkJ is correct. There are already moves afoot that the increasing coverage of the world with official ENC's will in the near term lead to the use of electronic charts on SOLAS vessels being mandatory as the means of navigation. Many SOLAS vessels are now all electronic (ie completely paperless) and even navies are moving to paperless navigation. All because of the increased safety delivered by electronic navigation.

As far as non SOLAS commercial vessels (generally the commercial fleet under 300grt or non passenger and not making international voyages) in my experience these either mostly use electronic navigation or if they don't and so rely on paper charts alone they don't use them in any serious way because they operate over short routes (eg harbour ferries) or in well known seas (eg inshore fishermen).

As far as pleasure boats are concerned for most (maybe for all for non international voyages???) there is no legislated requirement to carry any charts at all - so for boats required by law to carry charts (the commercial fleet and those very few countries that mandate that pleasure vessels on international voyages carry charts eg NZ) we are definitely heading to the situation where the use of paper charts will be illegal.

At the very least these matters are leading to the by far biggest part of the market for paper charts shrinking markedly with in the main only some pleasure users to be left as the customers, which infers that at least the cost of producing and maintaining current editions of paper charts will increase markedly (as will the production of official raster charts which are scans off them) and perhaps paper charts will only be produced by niche type providers to the pleasure market (rather than official providers) by purchasing or otherwise given access to the official hydrographic databases for that purpose.

Quote:
Originally Posted by Hampus View Post
...Just using electronics is fine, but you should know how to use paper and keep them on board. Anything else is plain out irresponsible.
You may wish to explain that to the increasing number of commercial and naval vessels that are moving to paperless navigation (no paper charts carried at all) for reasons of increased safety.

The above is all assuming official electronic charts (generally ENC's) are used. The comment has been made by others that the information on electronic charts is just the same as on the paper ones. That claim is entirely incorrect. Official paper, official ENC's (vector) and official raster charts are produced from the same hydrographic database but, for example, there is no natural relationship between what is on an ENC (vector) and what is on a paper chart produced by the same nation apart from the subset of data that is used in each case comes from the same wider hydrographic database and is administered under the same quality assurance policies.

In the case of non official electronic charts they are based on whatever hydrographic data the provider has been able to purchase or otherwise obtain from official hydrographic databases and the charts are built under the non official providers own quality assurance policies (whatever they may be). Non official charts of any kind are not authorised as meeting the chart carriage requirments on commercial vessels of most (all???) nations because their quality control is at large - and I know from my own experience with commercial customers that these secondary suppliers make serious slip ups.

So, in the end it will in the near term be the case that use of paper charts for many vessels will be illegal as the means of navigation as they will not meet the carriage requirements legislated. Those among the rest of us who are not yet resigned to the fact that the world moves on will dragged into the 21st Century using them too unless we choose paper for purely historic reasons rather than for pragmatic and safety oriented ones.

As others have said any chart can be incorrect and one should navigate with that in mind - my comments should not be taken to cut across that.
__________________
MidLandOne is offline   Reply With Quote
Old 13-03-2009, 23:50   #96
Registered User

Join Date: Dec 2007
Location: Brisbane
Boat: deboated
Posts: 672
As time goes by things change but they also improve as well. Could you explain how the official Australian charts (paper) showed a well known reef with a name and the electronic did not? Any chart paper or electronic needs a source for the information. Commercial vessels have a vast array of navigational equipment that the average cruising vessel does not. I will continue to carry both and I would guess so will most Blue water cruisers. This is a cruising sight not commercial vessel sight, so what they carry is of no relevance.
__________________
meyermm is offline   Reply With Quote
Old 14-03-2009, 01:14   #97
Registered User

Join Date: Sep 2007
Location: Colombo
Posts: 1,059
Quote:
Originally Posted by meyermm View Post
Commercial vessels have a vast array of navigational equipment that the average cruising vessel does not...
Err, like what? I have been on many commercial vessels that have less navigation equipment than many sail boats I have been on.

Quote:
Originally Posted by meyermm View Post
...This is a cruising sight not commercial vessel sight, so what they carry is of no relevance.
I am not surprised you have that opinion. It is easy to see through those that have a dismissive attitude to facts in order to protect an uninformed opinion one is married to. You know the saying - "Opinions are like assholes, everyone has one so they are not worth anything". Whereas facts are different.
__________________
MidLandOne is offline   Reply With Quote
Old 14-03-2009, 01:34   #98
Registered User

Join Date: Sep 2007
Location: Colombo
Posts: 1,059
Quote:
Originally Posted by meyermm View Post
Could you explain how the official Australian charts (paper) showed a well known reef with a name and the electronic did not?
I have had a quick check and I cannot find anything about this instance. When you say "electronic" I assume that you mean the official ENC as the official raster will be the same as the paper chart.

In which case if you can tell me which of the official ENC cells the error you claim occured in I will try and find out for you.
__________________
MidLandOne is offline   Reply With Quote
Old 14-03-2009, 02:17   #99
Registered User

Join Date: Dec 2007
Location: Brisbane
Boat: deboated
Posts: 672
Quote:
Originally Posted by MidLandOne View Post
Err, like what? I have been on many commercial vessels that have less navigation equipment than many sail boats I have been on.



I am not surprised you have that opinion. It is easy to see through those that have a dismissive attitude to facts in order to protect an uninformed opinion one is married to. You know the saying - "Opinions are like assholes, everyone has one so they are not worth anything". Whereas facts are different.
What is that opinion? That I do not use electronic charts? When I buy a top of the range electronic chart I expect it to be accurate. Fact is they are not always.
__________________
meyermm is offline   Reply With Quote
Old 14-03-2009, 04:46   #100
Registered User
 
Hampus's Avatar

Join Date: May 2008
Location: Sweden
Boat: Between boats
Posts: 463
Images: 6
Send a message via MSN to Hampus
Quote:
Originally Posted by MidLandOne View Post
I am afraid that you are in for a surprise because MarkJ is correct.
No, he's not You are correct in many of the things you write, but some things are speculation. When I said that the same errors exist on both digital (raster or ENC) charts as on paper, I referred to hydrographic data. As for man made errors, they are obviously not the same, but they are there on both.

Yes, there are moves to making ECDIS mandatory, and I have no doubt it will come to that. It is and has been allowed for several years, to sail commercially without paper charts. The requirements for this is that you should have two of eachother completely independent systems. Two ECDIS's, two radars, two GPS etc. Transferres to a leasure craft this would mean two plotters, possibly two GPS's if they aren't built in. Double set och charts (if on memory cards) and two completely different sets of batteries placed in different locations and fed through different distribution boards.

You have been correct this far, now to your speculation Explain to me how making the ECDIS mandatory (and this is just ONE mandatory ECDIS, it is not a mandatory paperless system), would render paper charts illegal. It has been mandatory for years to have a GPS receiver on commercial vessels. At the same time it is still mandatory for vessels not carrying a paperless system to keep a sextant and tables on board. The GPS didn't make the sextant illegal, they are in fact both mandatory. So, tell me about the ECDIS vs paper...

/Hampus
__________________
http://adventureswithsyingeborg.blogspot.com/
On the way back to Sweden.
Hampus is offline   Reply With Quote
Old 14-03-2009, 05:33   #101
Registered User
 
Exocet's Avatar

Join Date: Feb 2009
Location: 49-29 N, 124-44 W
Boat: Beneteau 305
Posts: 69
Some here have expressed the opinion that papper charts will be phased out in the future. If I do not have current charts, updated with NOMAR, and happen to get into trouble, my fault or not, my insurance company does not pay. With electronic charts there will be the questions, did he have the correct chart and was the plotter functioning properly befor the accident, both of which will have to be determined if the boat sank. A papper chart though seems to be the quick answer for the insurance companies. Now with thier money invested in political lobby groups why would they increase thier risk, or work load trying to figure out whether your plotter was working correctly, it's pretty easy for them as it is, you got no chart, you got no insurance. As far as commercial vessels go, kinda like pro hockey and 'AAA' Midget , play on the same field, not in the same league.
__________________
Exocet is offline   Reply With Quote
Old 14-03-2009, 05:44   #102
Registered User

Join Date: Dec 2007
Location: Brisbane
Boat: deboated
Posts: 672
Yes I also found the illegal bit fascinating along with comparing a cruising yacht to a commercial vessel
__________________
meyermm is offline   Reply With Quote
Old 14-03-2009, 07:18   #103
Registered User

Join Date: Mar 2009
Location: Morlaix Brittany France blog: theguerns.blogspot.com
Boat: Colvic Watson/32ft/Feels Good
Posts: 461
Images: 4
Send a message via Skype™ to feelsgood
I use a system that I started when gps first came out and have used it now for about 17 years. I make a note of the lat/long of all the compass roses on all my charts and put them into my H/H gps then when sailing I set the go to function to go to the closest comas rose. This gives me a distance and bearing to that compass rose. At any time I can see the distance and bearing to that rose and then take my piece of makralon (3cm x 50cm) I mark of the distance from the lat on the side of the chart on the plastic. then put the point of the deviders on the centre of the rose and slide the plastic against the devider point and turn the plastic untill it passes through the bearing. then mark the possition from the end of the plastic this gives a possition on the chart. This can be done in about 15 seconds when you are used to doing it. I hope this is clear as I find it easier to show this method than to explain in writinf. I will have to try to make a video of it
__________________
feelsgood is offline   Reply With Quote
Old 14-03-2009, 08:57   #104
Registered User
 
Strygaldwir's Avatar

Join Date: Dec 2004
Location: Deale, Maryland
Boat: SeaView - Privilege 37
Posts: 1,020
Images: 5
I have been very close to being struck by lightening 3 times. First time I was on the hard in the Lauderdale Marine Center. They had put another catamaran right in front of us. It got struck while a tech was working on the sail drive. Knocked him back about 5 feet. Took him to the hospital. He came back 5 hours later to say how happy he was to be alive!!

2nd time I was in the yard at Jarret Bay. Hit "Kardia" while in the yard (4 boats over). Fried almost every electrical device on board. They had to stay in the yard an extra 2 months replacing blown components.

3rd time we were at anchor (okay we were at dragging at anchor) in Oriental, N.C. We got caught in a serious blow. Lightening hit a boat about 100 feet from us. I saw the strike slam into the mast. Sparks were everywhere! I felt the heat. Well, I don't think we was directly struck. But I lost my helm instruments. Had to replace the anometer! I may have been hit, I am uncertain. But, it was enough to effect my electronics to a lesser degree (this included my chart plotter).

So, 1 in a million chance is probably the stats for getting killed by lightening. Situations probably increase the chances tremendously. But the point truly is the probability of losing navigational instruments. Aside from the strikes we have lost our navigational instruments twice and received "no fix" error a number of times. Once was when we blew the main fuse link to our batteries. Once was when a control cable on the inside of our chart plotter came lose and we were unable to turn it on. I still have yet to understand why we get the "No Fix" errors. The "No Fix" has always resolved itself in less than an hour. The other times took extended amounts of time to resolve.

So, now we do a number of things to mitigate this exposure. I carry a spare chart plotter. I friend gave me a monochrome version of a chart plotter that will plug into the connectors for our color plotter. We used this spare when we lost the internal cable. When we lost power it took a couple of hours to find the issue and restore power. We keep a chart book of the region we are in, we have a set of electronic charts that we carry on disk and on our laptop. Every hour and WHEN WE MAKE A COURSE CHANGE, we put a fix in our logs. We put our location, speed (Over ground) our courses (both true AND COMPASS). This lets us smoothly switch to chart navigation when something goes awry. We will get a hand held GPS one of these days as an additional backup. We'll store in the microwave. If we go offshore, we will consider this an essential back-up. Problem will be the charts in the hand-held don't have all the sailing areas and may not give the resolution. Thus the continuing need for paper back-ups.
__________________
Strygaldwir is offline   Reply With Quote
Old 14-03-2009, 12:03   #105
Registered User
 
Amgine's Avatar

Join Date: Dec 2004
Location: Vancouver BC
Posts: 1,384
Images: 1
Quote:
Originally Posted by meyermm View Post
As time goes by things change but they also improve as well. Could you explain how the official Australian charts (paper) showed a well known reef with a name and the electronic did not? Any chart paper or electronic needs a source for the information. Commercial vessels have a vast array of navigational equipment that the average cruising vessel does not. I will continue to carry both and I would guess so will most Blue water cruisers. This is a cruising sight not commercial vessel sight, so what they carry is of no relevance.
Yes, I can explain that error on the c-map. The encoding of the features which had negative depths (baring at low tide) was scrubbed by the data validation routine in certain display units because the data standard for depth has multiple encodings. This resulted in either incorrect data being displayed, or the feature not being displayed.

In other words, a programmer assumed the data was wrong, when it wasn't.
__________________

__________________
Amgine
Blog

On the internet, nobody knows you're a dog anchored in a coral atoll.
Amgine is offline   Reply With Quote
Reply

Tags
charts, navigation

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Paper Charts wanted stillbuilding Classifieds Archive 1 19-12-2008 23:09
PAPER CHARTS ed stewart Navigation 11 19-02-2008 20:23
Used Paper Charts Quercus Classifieds Archive 0 15-01-2008 13:01
Looking for paper charts ess105 Atlantic & the Caribbean 2 12-04-2007 19:15
Used paper charts available Bob Navigation 1 30-07-2003 02:43



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:03.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.