Navigational Aids

Post here about equipment carried on ships
User avatar
Pelican
Posts: 9734
Joined: Thu Aug 09, 2018 10:10 pm

Navigational Aids

Unread post by Pelican »

Having read the following I wonder if use of the sextant is still taught at Dartmouth and elsewhere in the R.N.?

Possibly for the Navi's Yeoman & others interested in NAVIGATION

"Sailors have navigated by the stars since the dawn of time. Now, fifty years after Neil Armstrong first set foot on the Moon in the Apollo 11 mission, we shouldn’t forget that even the Apollo astronauts relied on sextants to navigate to the Moon and back. Not only did a sextant help to get to the moon, but Astronaut Jim Lovell’s use of a sextant would be instrumental in saving the crippled Apollo 13 in 1970.

The Apollo sextant was a modern update of device that sailors have used for centuries. It played a key role in the three-part navigation system in the Apollo program. Much of the navigation was performed using ground-based radar. When that was not available, an inertial guidance system was used. The inertial guidance system tended to drift however and needed to be corrected periodically. To do so, the astronauts used a scanning telescope and a sextant to take star sights. These sights were used to correct the inertial guidance system and to confirm the accuracy of the ground-based navigation system. The sextant was also considered to be a backup against the possibility that the Russians would attempt to jam radio transmissions between Mission Control and the Apollo spacecraft.

“There are thirty-seven stars – and one is the sun,” said Apollo engineer Jerry Woodfill, “that provided an accurate way of aligning the spacecraft’s computer platform to allow the astronauts to steer their way through the heavens.”

The sextant had different uses during different phases of the missions. As described by Astronomy.com:

The Apollo sextant was used in Earth and lunar orbit, as well as while en route between Earth and the Moon. It played different roles in each of those contexts: in orbit around Earth or the Moon, the sextant could be used to compute the spacecraft’s altitude and position; whereas in transit between Earth and the Moon, it could be used to compute the spacecraft’s attitude (orientation), position, and velocity. A proper attitude during the flight to and from the Moon was critical for accurate course corrections and burns to reach the Moon and correctly insert the spacecraft into the desired lunar orbit. The device was used repeatedly throughout the Apollo program across many phases of the missions, up to and including re-entry.

All the navigators on the Apollo missions used sextants. The most well-known example perhaps was by Commander Jim Lovell, and ex-Navy aviator, whose use the craft’s sextant helped bring the crippled Apollo 13 safely home.

On the previous Apollo 8 mission, Lovell made a mistake entering a star sighting into the onboard computer. The mistake caused the craft to rotate approximately 90 degrees. To reorient the spaceship, Lovell used a novel technique using the Earth’s terminator line. The terminator is the line which delineates between night and day on Earth; where the Sun is shining and where it is dark. It worked to reorient the spacecraft, and Lovell became the only astronaut to have used the technique. Two years later, his experience may have saved his life and that his crew on the Apollo 13 mission.

Two days after launch, an oxygen tank exploded crippling the spacecraft. Short on oxygen and lacking the power to run the inertial navigation system, Commander Lovell needed to plot reentry manually. Because of floating debris from the explosion outside the craft’s window, he couldn’t take star sights with the sextant. So, he relied on his experience on Apollo 8 and used his sextant and the terminator line to plot a safe reentry. Without a sextant and Commander Lovell ‘s unique experience is likely that none of the Apollo 13 crew would have made it home.

In 2006, the US Navy stopped teaching celestial navigation to its officers, relying instead on GPS. A decade later, after concerns about GPS vulnerabilities, the Navy resumed teaching its cadets how to use sextants to find their location at sea, just the Apollo astronauts used sextants to find their way in space."

[The attached image shows Cdr. Lovell using the sextant on Apollo 8]
You do not have the required permissions to view the files attached to this post.
HMS Pelican 1938 - 1958 GGCV L86 U86 F86 What I Have I Hold ~ A wonderful bird is the Pelican its beak can hold more than its belly can.
User avatar
ivorthediver
Posts: 3659
Joined: Fri Aug 10, 2018 8:42 pm
Location: Cambridge Shore Battery

Re: Navigational Aids

Unread post by ivorthediver »

Thank you David,..... very interesting article......thanks for sharing it with us :)
"What Ever Floats your Boat"
User avatar
Little h
Posts: 1727
Joined: Sun Aug 12, 2018 6:53 pm

Re: Navigational Aids

Unread post by Little h »

The references in the comments section of this linked item may be considered to be broadly - nay - explicity related to the thread openers post; see:-


HMS SUTHERLAND on Twitter
@HMSSutherland

Even with all the cutting edge technology at the Commanding Officer’s disposal there are some items which have withstood the test of time - this board is used to keep a record of course and engine orders during a Replenishment At Sea (RAS).
#ThursdayThoughts
EATP4yKXoAIsbkS.jpg



----------------------------------------------------------

Whilst the board itself is obviously worthy of note, especially note the comments re. pens V pencils; and the reliability of the sextant!
You do not have the required permissions to view the files attached to this post.
Little h
User avatar
ivorthediver
Posts: 3659
Joined: Fri Aug 10, 2018 8:42 pm
Location: Cambridge Shore Battery

Re: Navigational Aids

Unread post by ivorthediver »

Well Harry Like you i'm the old school .."if it works don't fix it !"....simple is best...... in my book . :)
"What Ever Floats your Boat"
User avatar
Little h
Posts: 1727
Joined: Sun Aug 12, 2018 6:53 pm

Re: Navigational Aids

Unread post by Little h »

Little h wrote: Thu Jul 25, 2019 12:59 pm The references in the comments section of this linked item may be considered to be broadly - nay - explicity related to the thread openers post; see:-


HMS SUTHERLAND on Twitter
@HMSSutherland

Even with all the cutting edge technology at the Commanding Officer’s disposal there are some items which have withstood the test of time -
this board is used to keep a record of course and engine orders during a Replenishment At Sea (RAS).
#ThursdayThoughts

Been thinking about this 'state board' and the associated passage above (bolded by me).

Surely the info on the 'state board' is purely current; and functions as an aid or display of the course and engine orders at a particular point/period in the RAS evolution. I doesn't 'keep (or hold) a record' of anything, that function being fulfilled by the keeper of the bridge log and any other logs being kept by various departments in the ship.
Little h
User avatar
Little h
Posts: 1727
Joined: Sun Aug 12, 2018 6:53 pm

Re: Navigational Aids

Unread post by Little h »

Pelican wrote: Sun Jul 21, 2019 6:15 pm Having read the following I wonder if use of the sextant is still taught at Dartmouth and elsewhere in the R.N.?

Possibly for the Navi's Yeoman & others interested in NAVIGATION

Navigation by the sun and stars for BRNC midshipman
06 July 2017

Young Officers from Britannia Royal Naval College (BRNC) have been learning traditional navigation skills on board a Spanish Navy’s Sail Training Ship.

The two Midshipmen and their instructor spent nearly two weeks aboard the Elcano sailing from Dublin to the Dutch port of Dan Helder.

Working and living in the cramped mess deck alongside their Spanish counterparts, the two Young Officers settled well into life on board the sailing ship.

Their time on board presented both with opportunities that they would not have had at BRNC.

Midshipman Christopher Cotterill said: “The chance to navigate using a sextant and the position of the sun and stars was something completely new for me, and an excellent learning opportunity.

“In the modern world we use traditional methods less and less so to do it for real was a genuine thrill.

“Our time on board has really complemented the Initial Warfare Officer (Foundation) course, and has allowed us to consider the Rules of the Road from a very different perspective.”

The learning was not all one way with the Royal Navy Midshipmen able to pass on some knowledge to the Spanish.

Midshipman Matthew explained: “We were also able to show them some elements of coastal navigation that they had not been exposed to before, which was well received by our hosts.”

The two Midshipmen were not the only Royal Naval representatives on board the vessel.

As well as learning the basics of being a mariner whilst on board Elcano, the third largest tall ship in the world, the two BRNC Midshipmen assisted Sub Lieutenant Hamish Young who has spent the past four and a half months teaching English to the Spanish Midshipmen with lessons on ‘Jackspeak’, the name given to Royal Navy slang.

For Lieutenant Paul White, the instructor from BRNC who accompanied the Midshipman, this was not his first experience of the Elcano. In 2008, he spent seven months on board the ship as Profesor de Inglés, or English instructor.

Lieutenant White said: ‘Coming back to Elcano after so many years has been fantastic, and being able to give the two Midshipmen from BRNC the opportunity to embark in such an important ship to the Spanish Navy has been an honour.

"Hopefully the friendships they have made will endure, and undoubtedly they have learned a huge amount on board.”

Elcano is currently nearing the end of a five-month voyage which has included visits to the Caribbean and New York. She is expected to return to her home port near Cadiz this summer.

The Ship is named after the Spanish navigator, Juan Sebastián de Elcano, who was the first person to lead a circumnavigation of the earth in 1522.

He took over after the passing of the Portuguese explorer, Ferdinand Magellan, who had been appointed leader of the expedition. To date, Elcano has navigated over 2,000,000 nautical miles and rising, since her launch in 1927, more than any other sailing ship.

The Spanish Midshipmen on board were all in their third year of study at the Escuela Naval Militar (ENM) which is in Galicia, northwest Spain.

Source; royalnavy.mod.uk
Little h
User avatar
Little h
Posts: 1727
Joined: Sun Aug 12, 2018 6:53 pm

Re: Navigational Aids

Unread post by Little h »

NavyLookout
‏ @NavyLookout

Maintaining the old navigation skills in case modern technology fails or is jammed - taking a noon sight using a sextant

@HMSQnlz

#Westlant18
DmRWUXjWsAATk_h.jpg
DmRWiG0WsAcL02t.jpg

See also this associated YouTube video
You do not have the required permissions to view the files attached to this post.
Little h
User avatar
Pelican
Posts: 9734
Joined: Thu Aug 09, 2018 10:10 pm

Re: Navigational Aids

Unread post by Pelican »

VMT
HMS Pelican 1938 - 1958 GGCV L86 U86 F86 What I Have I Hold ~ A wonderful bird is the Pelican its beak can hold more than its belly can.
User avatar
Little h
Posts: 1727
Joined: Sun Aug 12, 2018 6:53 pm

Re: Navigational Aids

Unread post by Little h »

HMS SUTHERLAND
@HMSSutherland

·
1h
Old school technology still has it’s place in the @RoyalNavy
. Here’s SLt Mileham RN, one of our Young Officers taking a horizontal sextant fix as we approach #Plymouth Sound.
#FightingClanAtSea
ERJhJElWoAAjIw1.jpg
You do not have the required permissions to view the files attached to this post.
Little h
Post Reply Previous topicNext topic

Return to “Ships/Boats Equipment”