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Old 05-01-2020, 02:53   #1
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Help for a navigation noob please

Hi all, I've been perusing this subforum for a while now trying to get my head round the navigation jargon but I'm a bit stumped. I'm planning on sailing up the east coast of Australia and over to Indonesia, in the meantime I'm trying to familiarise myself with charts and routes, only I can't even understand what the different acronyms are
My head is spinning at CM93, OpenCPN, MBtiles, C-Map, Navionics, GE2KAP, OeSenc - what are they or at least what are the important things/differences to know? I'm not even sure which are proprietary names for files and which are formats (or neither).
I'm getting the impression that there are no free charts (outside a few areas like the US), is this correct? Is there no crowdsourced data?
Thanks!
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Old 05-01-2020, 03:50   #2
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Re: Help for a navigation noob please

To cover some of the terms you brought up -

OpenCPN is open source chart plotter software - this will read charts of various types and display them in a coherent and sane manner.

oeSENC is a plugin for OpenCPN which allows you to purchase good quality vector charts. You can purchase those from the oeSENC website. Often these come from the hydrographic offices of various countries and territories. I would recommend picking up a USB dongle to tie the chart licences to as each chart can only be tied to two pieces of hardware, be it a PC or a USB dongle.

GE2KAP is a process (involving software of the same name?) of converting Google Earth tiles to a format that OpenCPN will display. I think this is useful for where there are only old nautical charts available in areas which are constantly changing. Google Earth satellite photos of only a year (or less) old may give a more up to date "idea" of what the shallow areas look like. Perhaps this might be helpful around the reefs?

Navionics is a commercial vendor of marine charts and software - if you don't want to mess around with it this may be the route you go down, but there are sometimes "inconsistencies" that arise. It's pretty straightforward to install the app on your iPhone or iPad and select the area of charts you want to download. I think it can be linked to some instruments if they can be put on the Wifi somehow.

There are some attempts at open source marine charts by the same people who make the very helpful Open Street Maps. However, last time I checked they purposefully don't include soundings, and coverage may be spotty. Personally I would be cautious about solely relying on crowd-sourced charts for navigation, the reasons I'm sure you can understand.

CM93 - it's my understanding that newer versions of the CM93 charts don't work with OpenCPN and the ones that do work may be years out of date. I don't know much about these but you can google for "CM93 OpenCPN" if you want to find out more.

I'm not experienced with anything outside of my area so I'm sure someone will help you out soon with more local knowledge with regards to pilot books etc. In terms of jargon though there is much more to come in terms of actually navigating safely to a destination.

I don't know how much experience you have but it might be worth taking at least a navigation theory course to cover the basics if this is entirely new.
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Old 05-01-2020, 04:15   #3
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Re: Help for a navigation noob please

^ What he said. In Australia there are no free charts available. If you are going to run a PC based system using OpenCPN the OENSENC charts work out the cheapest as they are essentially the Australian Hydrographic Charts at about 10% of the price. Combine with the optional dongle and you can move the charts between devices (with some limitations).


If going with a tablet based solution, there are some reasonably priced solutions if not using OpenCPN but I'm not sure how well they stuck up for large geographical area coverage.



If using a proprietry MFD/Chartplotter then best to search for a package deal although the charts for these can be a bit pricey.


And I'd definitely recommend getting as much nav tuition/experience as you can. It's not quite as easy a driving a car down a highway to navigate on the open ocean!



P.s. your not escaping the law are you? It seems to be a popular route for this activity
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Old 05-01-2020, 09:07   #4
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Re: Help for a navigation noob please

First, you need to get your mind wrapped around the fundamentals of navigation. Navigation is a lot more than just using an electronic chart display system. You won't learn it overnight, either. You must apply yourself. It is roughly the same level of involvement as learning a new language.



I suggest three purchases right off the bat for your self schooling: a paper chart of your area, a kit of instruments containing a pair of triangles with protractor marks, dividers, a quality eraser and pencils, and a globe.


Why a globe? It illustrates in a very clear way the relationship between Latitude and Longitude, and why a degree of Latitude is the same distance anywhere, but a degree of Longitude is not, even though your mercator chart seems to think so. It helps you to understand that a flat chart is an approximation of the real world. It helps you to understand the geometry involved in Rhumb Lines, Great Circles, etc.



The paper chart and charting tools will give you a much more intimate knowledge of how a chart works. It is concrete. Well, it is paper, but it is a real world thing that you can touch and feel and see, and mark with waypoints and course lines and bearings and such. It has no video game vibe to it.



Do not confuse Navigation with Piloting. When you can use landmarks or bouys or daymarks or water color or visible shoaling for determining where you are, you are piloting. When you are out of sight of land and using electronic or celestial means of determining position and comparing them to your DR track, you are navigating.



A good early purchase once you have a handle on charts, set and drift, variation/deviation, etc is a sextant, either used and of good quality, or a new plastic one. Personally I would recommend a used Plath but many here will tell you that a plastic Davis sextant is fine. My reason for going with a more professional grade instrument is that the instrument error in plastic sextants can be large enough to hide small computational or table lookup errors, and you will sometimes not know when you have made a mistake. With a more consistent instrument, small errors stand out like a smashed thumb.



The logical way to LEARN navigation is to learn the basics first. That means celestial. Do not let anybody mystify this for you. It is not black magic and does not require a genius level intellect to understand it. Start with the more primitive techniques. Before there were accurate chronometers and radio time ticks, Longitude COULD be found, but the methods were a bit tedious and required considerable mathematical prowess to pull off. Latitude, OTOH, was pretty simple. At least is was pretty simple once a day. Well, three times a day if you were in the Northern Hemisphere and could shoot polaris. But a noon sun shot taken at Local Apparent Noon is a dead simple way to determine Latitude. Sailors of old would sail to a Latitude and follow it to a landfall, and rely only on DR for approximate Longitude for days or even weeks of passage. And that reminds me... actually your DR is the most basic navigational tool, but that will become quite obvious as you study. Anyway, if you look at your globe and imagine a sun out there you will see how when the globe is turned so that a given point is most closely positioned under the sun, so that the sun is exactly North or South of the position, the height of the sun can tell you your Latitude. So this is obviously the first thing to learn as you dive into the big kid's pool. We call this taking LAN, and it simply means determining your Latitude at Local Apparent Noon, when the Sun is at its highest point. The sextant does nothing except measure the angle between the horizon, you, and the celestial body which in this case is the sun. So actually pretty simple, right? There are some refinements that make this actually work with a practical level of accuracy, but that is the gist of it.


A bit more involved is taking a sight of a body, be it Sun, Moon, Star, or Planet, and reducing it to al LOP, Line Of Position. Still not hard. Anyway at the time of the sight, your position is somewhere on that LOP. If two LOP's taken at the same time cross, your position is where they intersect. You can not, obviously, take two sights at exactly the same time, but you can advance or retard them to a specific fix time, and the intersection is your fix, for that time.


You might ask why one doesn't simply take a sight and solve it for Longitude, and that is a good question. Quite simply, the azimuth/intercept method of calculating and plotting an LOP is more universal and more accurate. When you understand the Celestial Triangle, you CAN directly calculate a Longitude, if you have accurate time. And if you do NOT have accurate time, you can find it, and your Longitude, through methods that take advantage of the different speed of the moon compared to the motion of the stars, to figure out what the time must have been when the observation was made. This is then compared to the time of your clock, and a correction can then be made, so that Longitude can be found. Longitude is directly related to time.


There are tons of books on the subject. I just wanted to demystify a bit and illustrate how much you can do with just the distance above the horizon you observe a celestial body, and maybe an accurate time reference.


Celestial Navigation can be cumbersome at times, yes. But it is the basis upon which all Navigation is rooted. And it is the ultimate backup to electronic methods. The backup function alone is worth the time spent learning it. Sattelite or Terrestrial Systems CAN be hacked or just fail, even though this has (seldom) happened. Your electrical system CAN have a catastrophic failure leaving you in the dark and with no means of charging your devices. And the depth to which you will have learned geography/cartography/geometry will give you an entirely different perspective on what your little electronic gadget is telling you. If all you know is to turn on a screen and follow the arrows, you are no navigator and you do not know navigation, and you are not properly prepared for an ocean voyage. Period. OTOH, if all you have onboard for determining your position is a sextant and tables, you are not being very prudent or practical. As long as it works, and GPS and other systems pretty much always do, it is usually accurate, often within FEET, not miles. Sometimes that doesn't matter at all, and two mile accuracy is quite good enough. Sometimes it matters a lot, though if it is that critical, maybe you are skirting a bit too close to danger. You should ideally be in pilotage mode by the time your position is that critical. Anyway, the complete navigator is comfortable with both Celestial and electronic navigation, and always keeps a DR track on a paper chart, paper plot sheet, or electronic chart display, preferably both paper and electronically. Small boats have little space for spreading out charts, but once you understand Navigation, you can easily and quickly construct a plot sheet for your Latitude on any size paper you like, even standard printer paper, and keep your DR on that. Your DR is your absolute fallback system. DR is Ded Reckoning, short for Deduced Reckoning. You take your course and speed and time and construct a track. Simple. When you have a fix, you can compare and see what your set and drift are, and correct for it. If for some reason you cannot get a fix, you have a fuzzy sort of idea of where you are and where you will be an hour or a day from now, and it is a lot better than just guessing.



The most basic universal law of Navigation is that you never rely solely on one means of determining your position. The prudent mariner simply does not do that.


What they said about oeSENC and OCPN. Good system, flexible, not hardware dependant or OS dependant. You can run OCPN on your WinDOHs desktop, your Ubuntu laptop, your Android tablet or phablet. And it just works. Did I mention it is free? That should count for something, especially if you already feel bullied into dropping $400 on a used Plath sextant LOL! A pity the whole world doesn't recognize the public benefit of universal free charts. The thinking of most governemt hydrographic agencies is that the user should ultimately pay for the service of surveying, compiling, and publishing charts, but it is IMHO in the public interest that mariners know where the hell they are, especially in relation to ecologically sensitive areas or reefs where vessels can wreck and spill oil, stuff like that. Well, I can't argue with governments that do not give me the power to vote, so nothing I can do. The US does have free charts for all US waters and that is one thing that I can praise the powers that be for using common sense. Anyway, yeah you are kind of stuck with paying for your charts in Australian waters and you are just gonna have to suck it up.



CM93 is a valuable tool, but of course out of date and therefore unreliable in very near coastal or inshore waters. It is good for voyage planning. It is good for ocean passages well away from islands or reefs. It is widely available for download and yeah it is copyrighted, but because it is out of date and has limited utility, the owners don't seem to be going after folks who will after all, be exposed to the product and maybe become customers. It will also give you something to play around with while you learn to use electronic chart display systems such as OCPN, which plays this portfolio quite well.


GE2KAP is a great toolset. Sometimes a Google Earth shot reveals shore and bottom structure that is not obvious on official charts. When you can create your own chart from such images, you have another great tool at your disposal. As an example, look at the available chartage for San Pedro Entrance, through the Belize Barrier Reef. There are no permanent markers showing the channel. Not on the charts, not in reality. Sometimes you can eyeball your way in pretty good. The channel is about 200' wide, for small boats, but there is a hard turn just inside the barrier reef, necessitated by another bit of reef, and if you turn too soon or too late, you are screwed. You can start in with the sun high and at your back, but find that once inside, you can't see the bottom very well, and there are a few deep coral heads that will fool you and make you think it is time to turn NOW... A georeferenced Google Earth satellite shot in OCPN is a valuable backup tool in shooting this inlet. (JUST DON"T STAY GLUED TO THAT SCREEN!!!!!!!!!!!!) And there are countless other spots where a God's eye view in full living color lend an extra perspective to the official charts. Also, if you find yourself with out of date and uncorrected charts, (Really... what yacht skippers actually update their charts with official corrections?) bars and banks can move. A lot. Especially when there has been a hurricane or tsunami or similar catastrophe.


The crowdsourced movement has a lot of potential, but it hasn't really taken off in a big way yet. When EVERYONE pitches in with a system that automatically records hydrographic information and submits it to a central database, we will be on our way. Right now, we don't really have that. So data is spotty, and nearly useless. Right now for practical purposes I would say it is nothing more than a REALLY GREAT IDEA that I would love to see become a thing.
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Old 05-01-2020, 10:13   #5
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Re: Help for a navigation noob please

Given the plethora of good cheap tablet based navigation programs and cheap accurate gps/Glonass receivers why would anyone take the time and trouble to learn celestial navigation in 2020? Or even bother with paper charts? If you are worried about losing your navigation system get a backup system. We have 6 tablets and phones able to run Navionics and AquaMaps, three handheld Garmin gps units and a Furuno MFD Navigation system. We also have five GPS receivers onboard to feed them all including those built into various devices. The chance of being without accurate position and navigation data is vanishingly small.
If you want to use a sextant and reduce sun or star sights, you had better be good at number-crunching or have a calculator or two or three or more onboard to help out. Don’t forget to bring enough batteries too. A small math error can have huge implications.
I am sure the traditionalists will pillory me for stating the obvious, but this works for us as well as tens of thousands of others worldwide. If you are going to make your departure dependent upon your complete proficiency in celestial navigation you may be waiting a very long time.....
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Old 05-01-2020, 12:09   #6
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Re: Help for a navigation noob please

GE2KAP has been replaced by Sat2Chart and can create both mbtiles and kap charts from Google earth, SasPlanet and Geo-Referenced Images. You can download the latest verion here:

http://gdayii.ca/Downloads/Sat2Chart.V8.0.9.6.exe

There are sources of free charts for the areas you asked about including Australia. I'll ask my friend Valahalla to post a link to all his charts.
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Old 05-01-2020, 13:36   #7
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Re: Help for a navigation noob please

Quote:
Originally Posted by Woodland Hills View Post
Given the plethora of good cheap tablet based navigation programs and cheap accurate gps/Glonass receivers why would anyone take the time and trouble to learn celestial navigation in 2020? Or even bother with paper charts? If you are worried about losing your navigation system get a backup system. We have 6 tablets and phones able to run Navionics and AquaMaps, three handheld Garmin gps units and a Furuno MFD Navigation system. We also have five GPS receivers onboard to feed them all including those built into various devices. The chance of being without accurate position and navigation data is vanishingly small.
If you want to use a sextant and reduce sun or star sights, you had better be good at number-crunching or have a calculator or two or three or more onboard to help out. Don’t forget to bring enough batteries too. A small math error can have huge implications.
I am sure the traditionalists will pillory me for stating the obvious, but this works for us as well as tens of thousands of others worldwide. If you are going to make your departure dependent upon your complete proficiency in celestial navigation you may be waiting a very long time.....

I thought I explained that already. But to spell it out for you, it all depends on electricity. If you have none, but all of your various redundant navigational systems rely on it, you not only have no redindancy, but you have no navigational ability at all once your batteries are dead. Why are you opposed to learning, anyway? Plus until you truly understand the concepts involved, you don't understand navigation. Do you know how to set up a rhumb line or a great circle route, or a composite route? Oh yeah, simple. Let the chart plotter do it LOL. Okay, fine. And yes I applaud the "competition" to GPS that gives us more dependable satellite navigation, but that still does not constitute full redundancy. The fact is, celestial navigation is not that difficult to learn by the person of even very ordinary intellect. Don't, if you are not up to it. No problem here.



Yes, a computer and/or calculator are very useful for reducing celestial observations to LOPs. However, generations of navigators used plain old pencil and HO229 or other tabular solutions. And if you are keeping a DR, then you usually notice when you have made a mistake. The DR is THE most essential part of navigation.


Paper charts are indeed a hassle on a small boat. But as I said, you can construct a plot sheet in a few minutes on regular 8-1/2" x 11" paper, or you can get pre-printed pads of plot sheets and you only need to set your Latitude. Pretty darn simple and takes up no room at all. If you are a navigator, you can figure out either method, I am sure.
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Old 05-01-2020, 23:59   #8
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Re: Help for a navigation noob please

Quote:
Originally Posted by GrowleyMonster View Post
The logical way to LEARN navigation is to learn the basics first. That means celestial. Do not let anybody mystify this for you. It is not black magic and does not require a genius level intellect to understand it.

Indeed. The methods of celestial navigation have been purposely engineered for the majority of sailors* ... not rocket scientists. It is based on spherical trigonometry - but you don't have to know the first thing about trig to actually do it.


Quote:
Originally Posted by Woodland Hills View Post
Given the plethora of good cheap tablet based navigation programs and cheap accurate gps/Glonass receivers why would anyone take the time and trouble to learn celestial navigation in 2020? Or even bother with paper charts? If you are worried about losing your navigation system get a backup system. We have 6 tablets and phones able to run Navionics and AquaMaps, three handheld Garmin gps units and a Furuno MFD Navigation system. We also have five GPS receivers onboard to feed them all including those built into various devices. The chance of being without accurate position and navigation data is vanishingly small.
If you want to use a sextant and reduce sun or star sights, you had better be good at number-crunching or have a calculator or two or three or more onboard to help out. Don’t forget to bring enough batteries too. A small math error can have huge implications.
I am sure the traditionalists will pillory me for stating the obvious, but this works for us as well as tens of thousands of others worldwide. If you are going to make your departure dependent upon your complete proficiency in celestial navigation you may be waiting a very long time.....

GrowleyMonster did give several reasons why, but IMHO the most important was:


Quote:
Originally Posted by GrowleyMonster View Post
The most basic universal law of Navigation is that you never rely solely on one means of determining your position. The prudent mariner simply does not do that.

You can have 10,000 GPS units on board - but that won't help when someone is spoofing or jamming the GPS/GLONASS/etc. signal. And instances of this actually happening are becoming increasingly common. Or when a direct lightning strike takes out all electronics on board.


It is true that the chances of multiple GPS units all failing at the same time is very small - and I would certainly recommend carrying as many as possible on board. That's just common sense.



As for the argument that "[...] you had better be good at number-crunching or have a calculator or two or three or more onboard to help out", see above: All that's really required is the ability to perform simple arithmetic. No "number crunching" required. Everything required to produce a position fix could be accomplished by an elementary school student who can follow directions.



*This statement is not meant to imply in any way that sailors are not smart. But:


“Think of how stupid the average person is, and realize half of them are stupider than that.” -George Carlin
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Old 06-01-2020, 01:30   #9
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Re: Help for a navigation noob please

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Help for a navigation noob please
Lots on here and other youtube videos >>
https://www.youtube.com/user/penzancesailing/videos
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Old 06-01-2020, 01:57   #10
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Re: Help for a navigation noob please

Thanks so much for all the replies, I have a lot more to learn but at least now I have a much better starting point!
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Old 06-01-2020, 06:43   #11
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Re: Help for a navigation noob please

Great thread. I've been a few years into this now and it's not so easy to become expert, which is why it's fun to do whether you never have a need to use a sextant nor navigate across an ocean.
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Old 06-01-2020, 07:06   #12
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Re: Help for a navigation noob please

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GE2KAP has been replaced by Sat2Chart and can create both mbtiles and kap charts from Google earth, SasPlanet and Geo-Referenced Images. You can download the latest verion here:

http://gdayii.ca/Downloads/Sat2Chart.V8.0.9.6.exe

There are sources of free charts for the areas you asked about including Australia. I'll ask my friend Valahalla to post a link to all his charts.

No Linux version? I am sure it would probably run on Wine, but I don't like Wine and I don't like running any sort of VM on my nice secure Linux machines. I seriously distrust all that winDOHs stuff.
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Old 06-01-2020, 07:20   #13
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Hi all, I've been perusing this subforum for a while now trying to get my head round the navigation jargon but I'm a bit stumped. I'm planning on sailing up the east coast of Australia and over to Indonesia, in the meantime I'm trying to familiarise myself with charts and routes, only I can't even understand what the different acronyms are
My head is spinning at CM93, OpenCPN, MBtiles, C-Map, Navionics, GE2KAP, OeSenc - what are they or at least what are the important things/differences to know? I'm not even sure which are proprietary names for files and which are formats (or neither).
I'm getting the impression that there are no free charts (outside a few areas like the US), is this correct? Is there no crowdsourced data?
Thanks!
This is about the cheapest navigation system on the market and I have been using it for all my trips since 2012..
All you need is a laptop then plug in the USB and your good to go with CM93 world charts.. updates can be downloaded from the site as and when.

Nimble Navigator - Marine Navigation and Charting Software

I am not affiliated or receiving reward for this, just supporting a fellow sailor and full time liveaboard by word of mouth.
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Old 06-01-2020, 07:59   #14
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Re: Help for a navigation noob please

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This is about the cheapest navigation system on the market and I have been using it for all my trips since 2012..
All you need is a laptop then plug in the USB and your good to go with CM93 world charts.. updates can be downloaded from the site as and when.

Nimble Navigator - Marine Navigation and Charting Software

I am not affiliated or receiving reward for this, just supporting a fellow sailor and full time liveaboard by word of mouth.

So you are limited to CM93 charts? No Linux support? Android? Looks very convenient but those limitations are something to think about. Does the software have important features not found in OCPN? Does it cost less than a cheap USB GPS? I think it is a good concept but needs a lot more development. It is kind of hard to beat free OCPN and nearly all the charts in the world including CM93, and a cheap USB puck style GPS. Runs nicely on nearly all serious operating systems, and even runs on the $35 Raspberry Pi. Well, okay yeah you need a screen, too, but a 7" screen is pretty cheap, too. Runs nice on my old Samsung Note 3 as well as my Ubuntu laptops and RPi 3 and 4. Runs on Windows, too, I believe.



When they open up that Nimble system a bit more, and get the price down in the $30 range, it will be a very interesting system. E140 is just waaaaaaaay too much to pay for a very ordinary USB GPS and software that doesn't really do very much.



They charge money for just the software? Tsk tsk.


I will be keeping my eye out for further developments, though. It does have potential.
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Old 06-01-2020, 09:13   #15
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Re: Help for a navigation noob please

Quote:
Originally Posted by Woodland Hills View Post
Given the plethora of good cheap tablet based navigation programs and cheap accurate gps/Glonass receivers why would anyone take the time and trouble to learn celestial navigation in 2020? Or even bother with paper charts? If you are worried about losing your navigation system get a backup system. We have 6 tablets and phones able to run Navionics and AquaMaps, three handheld Garmin gps units and a Furuno MFD Navigation system. We also have five GPS receivers onboard to feed them all including those built into various devices. The chance of being without accurate position and navigation data is vanishingly small.
If you want to use a sextant and reduce sun or star sights, you had better be good at number-crunching or have a calculator or two or three or more onboard to help out. Don’t forget to bring enough batteries too. A small math error can have huge implications.
I am sure the traditionalists will pillory me for stating the obvious, but this works for us as well as tens of thousands of others worldwide. If you are going to make your departure dependent upon your complete proficiency in celestial navigation you may be waiting a very long time.....
In some countries and their merchant navies and military is the the law to have Paper charts available for the reasons stated A POWER CUT and good seamanship. also by understanding navigation on your charts will aid your skills on your chartplotter, which I may add is classified as an assistant to proper navigation.

Sorry (to Wife) I was looking at my blank chartplotter screen as the power went down, and I had no charts to plot my GPS on nor did I know how to take a bearing or understand any of the Cardinal bouys , so I did not see that reef out there
A bit like understanding the rules of the Sea but who cares about them
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