Why is Ocean Theory so Expensive?

[dom]

Some people attending these courses endeavour to grasp the concept to bring about a real understanding, rather than blindly following the old boy and his cartel, mickey taker colleagues. Understanding the spherical trigonometry and demystifying the concept can bring a good deal of pleasure to some and, I suspect, helps significantly in the application, especially when the almost inevitable school-boy errors of "Chosen Position" or "Same or Contrary"for example, are made.

Hmm, solving spherical polygons is a fairly tricky process which typically revolves around solving a set of differential equations using some sort of iterative method commencing with estimated latitude and longitude as starting values. I would have though that few RYA courses get into this level of detail, but could be wrong.

 

[lpdsn]

... as we found if you can sail a dinghy you can do any type of sailing.

Exacly. Has the added advantage that you can use the reservoir wall as a horizon for your sunsights if the real one isn't available. But do you not find your sight reduction tables get a bit wet?

 

[Skylark]

Hmm, solving spherical polygons is a fairly tricky process which typically revolves around solving a set of differential equations using some sort of iterative method commencing with estimated latitude and longitude as starting values. I would have though that few RYA courses get into this level of detail, but could be wrong.

Fair point. But just as school kids solve basic trig using Tables to derive, say, angle, using Sin, Cos & Tan arguments, the Ocean course teaches the student to derive Hc and Z from Declination and LHA arguments from within AP3270 Table.. More "O" level maths rather than degree, to offer an analogy?

My point was that understanding this is likely, imho, to lead to less mistakes when reducing a sight and deriving a PL as opposed to blindly following a Template or, even worse, using a PC algorithm to do it for you. Each to their own. There's no right or wrong intended.

 

[laika]

You've obviously not been on any course I've run then & many needed the full time.
The RYA state 40hrs, certainly the Ocean course takes all of that.

Obviously I haven't. That would be 9-6, 30 mins for lunch, 15 min tea breaks morning and afternoon with strict start/restart times? Never done an RYA or MCA course that approached that. Interested to know what the experience of others is. Your course sounds like the punter gets more for his or her money than elsewhere.

Some people attending these courses endeavour to grasp the concept to bring about a real understanding, rather than blindly following the old boy and his cartel, mickey taker colleagues. Understanding the spherical trigonometry and demystifying the concept can bring a good deal of pleasure to some and, I suspect, helps significantly in the application,

On the ocean theory course I did, I have no doubt that the instructor was a good practical navigator and there was nothing wrong with the "this is what you do..." instruction but with the exception of the fact that he brought in a couple of different sextants to play with (very worthwhile) it was little different to reading the cunliffe ocean sailing book: The instructor's practical knowledge was not backed up theoretical/mathematical knowledge

 

[Tranona]

Jane and chartered yachts two or three times a year for 20 years and then bought a boat to go long disatnace sailing and had no RYA qualifications. Jane had sailed dinghies in Gibralter, where her father was based, and I bought and sailed a Sheerwater cat, as we found if you can sail a dinghy you can do any type of sailing.

Not sure how being able to sail a dinghy helps you understand the subjects covered in Ocean Theory. The question is not about whether it is necessary, but how best to learn - and whether a structured course is good value.

So your contribution is absolutely useless to the OP.

 

[AntarcticPilot]

Were there not some youtube vids?
IIRC the Cunliffe book is not too bad.

A lot of total beginners seem to get stuck on the very basic principle.
Which is imagining a cone formed by a circle on the globe and a point a long way above it.
So far away that the cone is effectively a cylinder.
Measuring the angle of elevation between the surface of the cone and the surface of the globe defines that circle.
So if you know that angle, you can put yourself on a circle.
Draw 2 circles and there are only two solutions to your position where they cross.

A good teacher who can understand why you don't understand is a real bonus.
I think the bloke who taught my class also taught cse maths to prison inmates.
Much better than having a rocket scientist who can't relate to the mathematically inept.
Even if you understand, you still have to sit through them beating it into someone who doesn't.

I prefer to think of it this way:

There is a point on the Earth's surface which is directly beneath the celestial body you are observing. This is the nadir point. If you measure the elevation of that body, you are measuring the angular diameter of a circle centred on the nadir point of the body so you are the elevation converted to minutes of arc (= Nautical miles) away from that point. This is very simple to visualise if you think of a cross-section through the centre of the earth, the nadir point and your position.

 

[dom]

I prefer to think of it this way:

There is a point on the Earth's surface which is directly beneath the celestial body you are observing. This is the nadir point. If you measure the elevation of that body, you are measuring the angular diameter of a circle centred on the nadir point of the body so you are the elevation converted to minutes of arc (= Nautical miles) away from that point. This is very simple to visualise if you think of a cross-section through the centre of the earth, the nadir point and your position.

All true, even if it's hard using words for such a visual thing. Here is a very clear visual explanation right up to and then deftly jumping the tricky trig equations bit:

http://onboardintelligence.com/CelestialNav/CelNav4.aspx

 

[Paddy Layback]

Sure I never meant to start an argument. Keep it going lads, a few more of these posts and I wont even need to take the course

 

[Wandering Star]

Not sure if he's still around but there used to be a chap who ran practical courses from on board the Santander ferry. I think his name was Stokey something or other. I imagine that would be a great way to learn and to gain practical experience too.

 

[RobbieW]

Not sure if he's still around but there used to be a chap who ran practical courses from on board the Santander ferry. I think his name was Stokey something or other. I imagine that would be a great way to learn and to gain practical experience too.

'Stokey' Woodall, https://www.internationaloceanservices.co.uk/ - met him in Horta a few years ago

 

[lw395]

I prefer to think of it this way:

There is a point on the Earth's surface which is directly beneath the celestial body you are observing. This is the nadir point. If you measure the elevation of that body, you are measuring the angular diameter of a circle centred on the nadir point of the body so you are the elevation converted to minutes of arc (= Nautical miles) away from that point. This is very simple to visualise if you think of a cross-section through the centre of the earth, the nadir point and your position.

I see that as one step on from what I was trying to say.
Once you've sussed that the elevation defines the circle, the above starts to explain how the circle can be drawn.

I've seen YM instructors struggle to get much simpler concepts into other people's heads.
E.g. adding up a bunch of vectors.
Or tying a bowline.
One acquaintance went through more than one RYA course, forgot how to tie a bowline before getting off the premises.
A few years later a teacher friend got the message through over a pint and the knowledge stuck.
I think Ocean is a hard course to teach.
Then you have the fact that a lot of instructors have zero actual training and little experience in teaching.

 

[bedouin]

I agree that astro is very hard to teach well. If you go into the maths you have to teach about spherical geometry that many people won't have met before (I doubt if it is even on A Level courses these days). That is both hard to teach and hard to understand.

Otherwise you teach it along the lines of "you put that number in that box" which while very easy and reliable does not give any insight into how it all works.

 

[RobbieW]

I agree that astro is very hard to teach well. If you go into the maths you have to teach about spherical geometry that many people won't have met before (I doubt if it is even on A Level courses these days). That is both hard to teach and hard to understand.

Otherwise you teach it along the lines of "you put that number in that box" which while very easy and reliable does not give any insight into how it all works.

I'd argue that, for a navigator, astro is simply a variant on a transferred position line / running fix. I didnt feel the need to really understand the mathematical theory involved in taking a bearing from a celestial object when I took the course, and still dont. I found that creating my own proforma for the steps involved helped me to understand the process - and I think it is the process that is the key to using the technique.

 

[lw395]

I did my course some years ago and haven't used it in years.
The knowledge of how to turn the handle has faded, the understanding of the basics remains.
I've forgotten what all the little corrections are called and so forth.

To use it for navigation, you only need to get the handle-turning right.
Same as using a GPS, you don't need to be able to build one from transistors.
But having the understanding from the course, I reckon I could re-learn the detail very quickly.


Also one thing I do remember from the course is that it's not just astro nav.

 

[GHA]

Also one thing I do remember from the course is that it's not just astro nav.

Out of interest - how much of it is astro anyway?

Sailing oceans is quite a subjective thing, IMHO, most of it anyway. Two boats could mean 2 very different experiences with what works for one boat being a very bad idea on another.

Would you fail if you disagreed with the RYA way?

 

[RobbieW]

Out of interest - how much of it is astro anyway?

Sailing oceans is quite a subjective thing, IMHO, most of it anyway. Two boats could mean 2 very different experiences with what works for one boat being a very bad idea on another.

Would you fail if you disagreed with the RYA way?

From memory (it was 12 years ago) about 60% is astro, it really depends on how well the students grasp the method to produce acceptable results. IIRC we had one or two who were slow on the uptake and our instructor had to move on.

Heres a link to the YM Ocean examiners notes. I dont really subscribe to the 'RYA way' idea at Offshore and Ocean levels, even the sainted Cunliffe suggests that there are many ways of doing most sailing activities but some will get you into trouble quicker than others. A friend, who is a YM examiner, said to me that in the back of his mind, examining for Offshore, was the thought "would I trust this person to take my sister/mum across the Channel" - I think that can be extrapolated out to crossing the Atlantic.

 

[JumbleDuck]

I agree that astro is very hard to teach well. If you go into the maths you have to teach about spherical geometry that many people won't have met before (I doubt if it is even on A Level courses these days). That is both hard to teach and hard to understand.

I would suggest that spherical geometry is actually very simple. It's spherical trigonometry that's a right old bugger.

 

[bedouin]

I would suggest that spherical geometry is actually very simple. It's spherical trigonometry that's a right old bugger.

Ah but trigonometry is just a branch of geometry so the one includes the other

 

[GHA]

Heres a link to the YM Ocean examiners notes. I dont really subscribe to the 'RYA way' idea at Offshore and Ocean levels, even the sainted Cunliffe suggests that there are many ways of doing most sailing activities but some will get you into trouble quicker than others.

This from the notes seems to address it quite well, Ta..

The candidate’s views on many of the subjects in these sections may be totally different tothe Examiner's but they may still be perfectly workable.

 

[AntarcticPilot]

I'd argue that, for a navigator, astro is simply a variant on a transferred position line / running fix. I didnt feel the need to really understand the mathematical theory involved in taking a bearing from a celestial object when I took the course, and still dont. I found that creating my own proforma for the steps involved helped me to understand the process - and I think it is the process that is the key to using the technique.

Horses for courses. For me, doing something involving mathematics where I don't understand the principles behind it is almost impossible. I can't remember things as recipes to follow, only as logical and connected sequences. The latter has the advantage that if necessary I can recover the method by asking "OK, what am I trying to achieve?"

I suppose that I'm lucky in having a very solid grounding in spherical trigonometry, both in education and in my subsequent career. The basics are actually quite simple, though - there are only two "rules" underlying the whole thing - the Sine rule and the Cosine rule. Know them and you've got the whole of spherical trigonometry at your fingertips. Things like Haversines and suchlike are only there to make the computation faster and more reliable at the expense of obscuring the actual method.

I'm no mathematical genius, and my need to understand the theoretical basis of what I am doing can be a hindrance - I never came to terms with Quantum Wave equations and suchlike in Chemistry! The problem there is that there isn't a good visualisation of what you're doing, and you really do have to accept the maths "as is"; understanding it is reputedly beyond even the greatest physicists!