compass variation

benjenbav said:
Tim, I think I'm right in saying that your learned your nav in the world's finest school. Did the RN teach its young gentlemen by methods involving remembering whether virgins were partial to particular brands of confectionary or was it just the spectre of the least appealing of rum, sodomy and the lash being applied whihc assited your mental processes?
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Yes, I did -- at least, some of it.

And I can't remember all the mnemonics they gave us: there was probably even one for remembering which foot to put in front of the other. We certainly had True Virgins, I think we had Error East, and "Rub Your Bicycle With Grease" came in there somewhere -- though I'm damned if I can remember what it was supposed to help us remember!

But the one I always use, even now, for compass corrections was CadET (to get from C to T you ad Easterlies).

But I don't think even the RN thought Midshipmen needed a mnemonic to remember that if you start west and come east a bit, you are less west than you were when you started! :)
 
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kid's inheritance said:
on my day skipper homework, I have to find the difference in variation between two different years.I've poured over the training map ,especially the rose but can't find how to calculate it.Any help appreciated,I don't want the answer but a clue of how to start!
Thanks
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Its 7deg30'W 2005 (8'E), which means the W variation is decreasing by 8'E each year.

So for 2007, it would be 7deg30'W - 16'E
In 2012, it would be 7deg30'W - 48'E
 
timbartlett said:
Sorry, guys, but I really do think you are making this far more complicated than it really is.

If the Variation was Westerly, but it is getting more Easterly year by year, then it must be reducing.

If the Variation was Westerly, and was getting more Westerly year by year, then it would be increasing.

Isn't that easier than trying to remember mnemonics that apply to something completely different and trying to force them to fit?
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Blimey, why on earth dont they teach it that way instaed of all this nonsense.
So, who still makes such corrections onto paper charts and so in their passage planning on their epic trips from Hamble to Cowes ?
 
PaulGooch said:
Who still uses paper charts ?
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I guess I am thinking that its fair enough to mention this in passing on a course, as it could be siginifacant in some world locations, but the amount of time spent on it and on useless test questions was stupifying.
 
I use paper charts, on my knee in the cockpit - coz my plotter is on my laptop in the cabin. But I don't plot a course on them - but then I don't often get the chance to make a passage out of sight of land. SWMBO & Grandkids like beaches more than sailing.

The laptop plotter helps me see my actual course made good & actual heading which is nice in an area of strong tides swirling around the coast.

The whole point of RYA nav course is that if you know the theory & can do it in detail, then you will understand when you can (& can't) cut the corners. Fag packet nav (like wot I do) is only fine if you understand the importance (or not) of the bits you ignore.
 
gjgm said:
Blimey, why on earth dont they teach it that way instaed of all this nonsense.
So, who still makes such corrections onto paper charts and so in their passage planning on their epic trips from Hamble to Cowes ?
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No-one (I hope). But maybe some people have ambitions beyond the visible horizon. I certainly hope so. :)
 
Philiz said:
Nah, just a plotter and a pile of paper charts
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Ah. Plotter first. If it packs in, laptop with handheld GPS. If that packs in, handheld GPS with paper chart. If handheld GPS packs in, handheld compass with paper chart. Any further problems an i know my luck is well and truly jinxed, so i'm jumping over the side :(
 
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PaulGooch said:
It would be, yes. Last resort is the paper charts and magnetic compass. But seriously, in this day and age, what would be the chances of the GPS system being shutdown ?
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Less and less. When we talk about "GPS" we usually mean the American Navstar system. But there is also the Russian Glonass system, the European Galileo system is in build, and the Chinese system which currently covers the Far East is being expanded to provide global coverage.

So before long we'll be less reliant on just the American system, and there is talk of receivers that will be able to pick up signals from different systems, so just one box on board that will give you a position corrected from up to 4 autonomous satellite systems. World economy permitting, of course
 
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