AntarcticPilot
Well-Known Member
AMEN! Oddly, what really drove the intricacies of spherical Trig into me was having to use it in crystallography - the connection isn't obvious!
Why is Ocean Theory so Expensive?
- Thread starter Paddy Layback
- Start date
AMEN! Oddly, what really drove the intricacies of spherical Trig into me was having to use it in crystallography - the connection isn't obvious!
JumbleDuck
Well-Known Member
In maths - which I taught to undergraduate engineers for many years - it is always important to distinguish between "hard" meaning "difficult" and "hard" meaning "complicated". The basic concepts of astronavigation are very simple (ie it's not difficult), and can fairly easily be explained in a few diagrams. Working them out's a bugger (ie it is complicated), though, because, basically, spherical polar coordinates are a pain when it comes to changing axes. Life would be so much simpler if the earth was a cube.
As you say, haversines are just a way of making the calculation a little quicker but they obscure the simplicity of the underlying concepts even more. It's a big like long division, which is only an outdated method of performing certain calculations and not, as too many politicians think, of any fundamental mathematical use or interest. Doctorate in mathematics here, and I've never done a long division in earnest in my life.
Just as calculators have made Napier's bones, log tables, long division and slide rules obsolete, so have all manual methods of reducing sights been obsolete since the first calculator programs (TI57? Casio FX601P?) to do them came out. Insisting on pen and paper methods is bloody minded Luddism. Yeah, I suppose a calculor might stop working (I have a Sinclair Oxford 100 from 1975 which is still going perfectly) but then you might drop the sextant over the side and that would put you just as far up the Swanee.
And relax.
JumbleDuck
Well-Known Member
I used to do a little of that. Miller indices, slip planes, that sort of thing. Very basic, still fiddly.
roblpm
Well-Known Member
Is there anyone under 50 on this thread?
How much longer will people attend these courses for? How much longer will the rya demand astro? Seems doomed to me. People will routinely have 20 gps devices on their boat. And in the future the chips will have galileo and the Russian one too.
How much longer will people attend these courses for? How much longer will the rya demand astro? Seems doomed to me. People will routinely have 20 gps devices on their boat. And in the future the chips will have galileo and the Russian one too.
GHA
Well-Known Member
At a guess it will continue. GPS is unlikely to fail and if it does you might well be better way out on the ocean anyway as it will be chaos. That's not really too relevant. From the point of view of an ocean skipper the instinct is for complete self sufficiency, it's highly unlikely that you'll loose GPS but it might so the feeling of uneasiness that the boat is reliant on something not under your control is a very strong motivation to make sure you've done all you can to change that.
The other side is that a thousand miles from land day after night after day there's something magical about visualising the lump of rock we live on spinning through space among a few billion stars in this galaxy alone.
Worth it for that alone.
Long may it continue that people are interested
.
JumbleDuck
Well-Known Member
Skylark
Well-Known Member
We can't "blame" RYA for including Astro in its Ocean course.
For some, this can lead to a Certificate Of Competence issued by RYA on behalf of the MCA. This can become a professional seafarer qualification hence it falls within the framework of maritime law. The MCA gives its approval of all relevant RYA courses.
Ultimately it starts with the UN with its specialised body the Imternational Maritime Organisation. In the UK, our government as members of the UN delegates the responsibilities to the MCA.
For some, this can lead to a Certificate Of Competence issued by RYA on behalf of the MCA. This can become a professional seafarer qualification hence it falls within the framework of maritime law. The MCA gives its approval of all relevant RYA courses.
Ultimately it starts with the UN with its specialised body the Imternational Maritime Organisation. In the UK, our government as members of the UN delegates the responsibilities to the MCA.
Barnacle Bill
Well-Known Member
For step-by-step Astro instructions, and loads of other stuff that's covered in the Yachtmaster Ocean course, see Reeds Ocean Handbook.
http://www.bloomsbury.com/uk/reeds-ocean-handbook-9781472913067/
By the way, the next GPS 'week number roll-over' event is in two years time, on 6th April 2019; I mention this because on the last one a number of receivers failed, and had to be re-booted.
http://www.bloomsbury.com/uk/reeds-ocean-handbook-9781472913067/
By the way, the next GPS 'week number roll-over' event is in two years time, on 6th April 2019; I mention this because on the last one a number of receivers failed, and had to be re-booted.
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stephenh
Well-Known Member
The US Navy gave up astro in 1997 (?) and now , 20 years later are bringing it back.....
see :
http://www.naval-technology.com/fea...nstated-as-cyber-warfare-looms-large-4809513/
The RN have never stopped teaching it.
[70521]
Well-Known Member
Friends on a well equipped boat, two day out and the electrics go bang. So they pulled out the sextant and tables and continued across the Atlantic. What would you do?
dom
Well-Known Member
....use my phone or perhaps one of the two dedicated back-up GPS machines which live in a Faraday Cage (converted biscuit tin) alongside a few dozen spare batts.
However re the opening question: £450 for a week's high-intensity tuition in a warm classroom seems very good value to me. I think we have to collectively get over the fact that our chosen leisure activity is someone else's livelihood. My squash coach charges £50/hr, whereas my charge-out rate for a mate is £0. No problem there.
JumbleDuck
Well-Known Member
Use the spare GPS? Or the other spare GPS? Or, if setting out to cross the Atlantic, the other spare GPS?
bedouin
Well-Known Member
If a single failure knocked out all navigation equipment beyond repair I am not sure I would call it a well equipped boat
ex-Gladys
Well-Known Member
It may not fit the OP's location, but winter evening course for Ocean at West Mersea is <£100
KINGFISHER 9
Well-Known Member
Is there such a thing as Mathematical Dyslexia? .... that's me! Afraid I'll have to give Saint Thomas de Cunliffe a miss and stick to GPS!
[70521]
Well-Known Member
I am an old fuddy duddy and like the old way of doing stuff, but on the boat that my friends were on the owner cranked up the new fangled radar thingi and and bang, blew all the electrics. I suppose a position once a day would be fine, but how do you charge your phone again with duff electrics?
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[70521]
Well-Known Member
The word you want is dyscalculia
roblpm
Well-Known Member
£10 garmin etrex off with aa batteries ? 5 of them? In separate biscuit tins?
roblpm
Well-Known Member
And maybe i understand the requirement for professionals who are responsible for someone elses potentially very expensive property. But if i am in charge of my own boat when my 10 gps's have died an i am in the middle of the Atlantic i will continue heading west til i hit somewhere?
JumbleDuck
Well-Known Member
OK, sextant fans, you're taking a noon sight, the boat lurches and you drop the sextant overboard. Now what?