Astro nav advice wanted, and which Atlantic Chart.

[newtothis]

I didn't realise that it couldn't be downloaded on that site. If anyone can direct me to a reliable and free PDF host I would be no end pleased, this Calameo site is my third. In the meantime PM/DM me your email addy and I will send the PDF directo, gratis, free, and for nothing.

If you have a free Google Drive account you can just put it there, make it available to anyone with a link, then share the link.

 

[Frank Holden]

If you have a free Google Drive account you can just put it there, make it available to anyone with a link, then share the link.

Thankee, maybe I should get out more as I had never heard of that before. However PDFhost is working again so I'll just leave it there. Docdroid was good until they started wanting money as I could see views and download numbers.

 

[Skylark]

Thank you for your response, never expected a YM examiner to reply! Really useful info, thank you.

Prep & management of boat and crew I am fairly comfortable with having done a few longer trips, Certainly need to focus on the detail there, but the Astro nav is totally new, and somewhat scary!
To be honest, in 50k miles of sailing, including several longer passages, I have never used it nor seen it used properly.
So it’s somewhat a case of learning how to pass the exam. (Yes I don’t doubt it’s handy if all the satélites fall out of the sky or your electronics explode & the iPad dies) but I guess I’m looking for the most idiot proof way to get the desired results.

I signed up to an online course, but find the content difficult to digest. Thanks for your recommendation of Tom Cunliffes book, he has a style of passing on information that makes sense.

Will get the full nautical almanac, thank you.

And are any of the apps worth getting?

Thanks.

Where are you based?

It’s not unusual for people to struggle with the online course. There’s a lot of fog to a newcomer and perhaps a day spent one to one with an instructor would help to demystify it. Once the penny has dropped, it really is quite straightforward.

An up to date RYA G158 Yachtmaster Syllabus and Logbook is a worthy investment as it gives full details of course content plus prerequisites for the exam.

With regard to Charts, I create my own plotting sheets from plain A3. It’s 7 or 8 sheets stuck side by side for a typical east to west crossing. Easy enough to then plot the fix on to the Imray Atlantic Passage Chart, 100. Nice to see the daily slow but steady progress.

There can be long days during a crossing. What better way to pass an hour or so practicing the gentle art of celestial navigation.

 

[zoidberg]

While 'tombuoy2' doesn't reckon on finding much future use for astro, there's a growing number of pros now uncomfortable with the extent of GPS/GNSS signal interference these days to persuade them to scrape the rust and cobwebs off their sextants and dust down their skills 'Just In Case'.

There's likely benefit to be had by 'tombuoy2' by taking his sextant down to a south-facing harbour on a clear day - where his position is known within a 'smidgen' - and practising the various simple sextant-handling techniques/procedures until they are easy and familiar. Record the Heights and Corrected Times, take them home, and plot them out. Merchant cadets got plenty of 'handling' practice before they started trying to take, record, resolve/'work up' a sight and then plot it.

It's asking a lot to read a few pages of Cunliffe/Blewitt, set off across a bouncy sea, and expect to get it right first time, straight out of the box.

There are many, many ways of 'reducing a sight' to something that could be pencilled onto a paper chart ( my old copy of 'Bowditch - An American Practical Navigator' - lists over 55 of of them ) and the RYA's preferred 'Air Tables' procedure is sufficiently close to idiot-proof that the RAF/HMQueen used it in training their Vulcan bomber navigators how to find places with accuracy and reliability. After all, they did manage to find the Falkland Islands....

I myself used the Reeds Astro Tables ( used to be called 'Cdr Harry Baker's Heavenly Bodies' until we all went woke and prissy ) on a Qualifying Passage from Liverpool, outside Ireland, to La Coruna using only astro and other trad-nav practices. We managed to find Europe again, more or less where we expected it to be.

And you will, I really expect, take pride and satisfaction from plotting your own astro fixes 'close enough for government work' aka your GPS fix.

 

[Red Panda]

Timely thread. I did the RYA theory course a few years ago, but life intervened and I never put it into practice. I’ve been thinking I need to buy a sextant, find my course notes, and try to remember how it all works.
Thanks Frank Holden for putting up the PDF, I’ll have a look at that later.

 

[Frank Holden]

...
There's likely benefit to be had by 'tombuoy2' by taking his sextant down to a south-facing harbour on a clear day - where his position is known within a 'smidgen' - and practising the various simple sextant-handling techniques/procedures until they are easy and familiar. Record the Heights and Corrected Times, take them home, and plot them out. Merchant cadets got plenty of 'handling' practice before they started trying to take, record, resolve/'work up' a sight and then plot it.
....

I had never handled a sextant before the day I took my first sight. OK I had an old vernier one from the 1890s given to me as a pup that my dad had picked up at the local auction rooms that I would play with in the back garden. But apart from that. A couple of years at sea, bound from 'straya to the UK. Cochin for crew change , Aden for bunkers. Now my father was a tanker master and his ship had called at Aden a week earlier. He landed his 1950 Plath with the ship's agent and it was delivered to my ship with much pomp and ceremony when we arrived.
First day at sea on the way up to Suez, 'here is an A5 sight book, rule it up thus, stand with me on the bridge wing, put lower limb on horizon and wobble it side to side a bit, when I say 'STOP' read altitude orf arc. Come into chart room and copy what I do with almanac and Nories'.
And that as they say was that.
I can teach any mug punter bright young man how to take a sight in a forenoon. Sadly most keep asking 'but why is it so??' That slows things up a bit.
Story about my astro PDF is maybe interesting to some. As a side hustle I was a feature writer for the Australian sailing mag 'Cruising Helmsman' through the 1990s . Mainly cruising ground articles, a bit of technical stuff, a few product reviews, etc. Asked to write the astro nav course. Ok. Summary of what each month would be about required ! I have no idea!! And for the next 12 months I just winged it from there. I believe 3500 signed up for the course which simply involved taking out a year's subscription to the mag.
I'm currently translating it into spanish for some Chilean chums.

 

[BobnLesley]

I found Mary Blewitt's book (I think called just Astro or perhaps Celestial Navigation) inexpensive and easy to follow; it certainly did the job for me.

 

[Tombuoy2]

Hi, OP here. Back home from the aforementioned trip. Many thanks to you all for some great advice. We had a great trip, left Tenerife 11th November to get ahead of a big low which gave us the somewhat unusual start of 3 days beating down towards the Western Sahara coast. The trades kicked in near Cape Verde and we had a super ride with low seas and just enough wind all the way to Grenada, arriving on 1st December.

I took a variety of Astro nav literature advised in here and as well as reading it myself, shared it with my more learned mate. This was key as he could explain the bits that I struggled with. As advised by John Morris on here, we ended up using Tom Cunliffe’s book in conjunction with the full nautical almanac. We took loads of sights and spent hours reducing and plotting, and did get a buzz when the majority of plots agreed (close enough) with the gps track.

So thanks to advice from you guys, Cunliffe’s easy style of explaining, and my mate’s guidance, I have gained a basic understanding in a subject that initially seemed impossible to me. Thank you all.

 

[Leslie frank]

Good evening, newby to the forum so please go gently! I am hoping for some advice from those more experienced than I.

I have foolishly agreed to join a mate in trying to obtain YM Ocean qualification. Having happily sailed for years with just an ICC, we did the YM Offshore recently, and now face with the prospect of Astro navigation. Problem is I am not the most academic at the best of times!

Realistically, this Astro nav bit is a means to an end for me, I just need to learn enough to take a few sights good enough to pass the exam. I doubt I’ll use the Astro nav in the future, as on my previous 8 transatlantics we have been happy enough with navionics etc.

So what do I need to cover the basics? I’m thinking sun sights only.

I’ve picked up a secondhand Sextant & ordered the RYA Astro navigation handbook.

Should I get Tom Cunliffes book too if it makes it easier to understand?

Was going to order Reeds Astro Navigation tables 2025, is that the most convenient?

Are any of the apps worth considering?

I’d like to plot the sights on a chart. Seen Imray chart 100 but it has a conical projection, is that ok or is Admiralty chart 4012 more use?

Is there anything else needed?

I’m helping a friend take his boat from Canaries to Caribbean next month, so hoping to learn the basics and use the trip to get the necessary sights.

Any advice gratefully received! Thanks.

I really rate Tom Cunliffes little book. Then I use the large imray plotting sheets which have good proformas on the back for noon sights and sight reductions. Then transfer the plot onto your nav chart of choice. I do a fair bit of astro as it helps fill the long days of a passage.