Sextants : Waking up!

[Ivan Cloherty]

US Naval and Merchant Academies stopped teaching the use of the sextant in 2006, it is now being reintroduced this year in all academies, because so many ships have experienced electrical failures for a variety of reasons, even one ship forgetting to fill generator tanks. Many could not effect repairs before battery power ran out and some ships had a bridge full of navigators who had no idea of celestial navigation or horizontal angles. However the deciding factor was a Navy ship running aground on a reef and becoming stranded as they relied soley on electronic charts and GPS, both of which had been wrongly programmed and not one navigator bothered to take bearings of three lighthouse visible from their navigation area. In a statement the Defense Dept stated that it was essential for all vessels to know where they are at all times and especially in areas close to Iran, Iraq and North Korea and the Chinese coast.

Remember the time when we had to carry our own, a bloody nuisance when joining a ship already trying to juggle with a suitcase and kitbag full of uniforms and working gear (including oilskins) for all weathers

Common sense it seems has prevailed

[Jim Brady]

Ivan I watch a lot of antique shows on the TV such as Flog It sextants often come up for sale and they don't bring any money atall.The other day there was what looked to me a very good one in a box it struggled to reach £60.00.
Regards.
Jim.b.

[Ivan Cloherty]

Ivan I watch a lot of antique shows on the TV such as Flog It sextants often come up for sale and they don't bring any money atall.The other day there was what looked to me a very good one in a box it struggled to reach £60.00.
Regards.
Jim.b.

A sad fact of life Jim, people just don't know what they are and that they were the only thing that has little changed since the late 1600's, I purchased mine second hand so guess it had travelled the world before I| got it, it circumnavigated the world with me, even used on the coast for horizontal angles, doubt I could do it now though!

[j.sabourn]

Of Course you could Ivan, it never leaves you. The Sextant is the instrument for measuring any angle in any plane, either vertical horizontal or oblique. It is based on two main optical laws 1. the angle of incidence is equal to the angle of reflection and 2, If a ray of light suffers two successive reflections by 2 plane mirrors in the same plane then the angle between the first ray of light and the second ray is equal to twice the angle subtended between the inclination of the mirrors. That's from 60 years ago and any navigator that didn't know that does not deserve the title. It is hard to believe that the modern navigator doesn't know. I suppose the same applies to the basic principles of signalling and the morse code. God help Britain if it ever had to fight a sea war without the aid of modern electronics. One of the basic questions for 2nd. mate and would of been out the door if didn't know. Cheers JS Even remember most of the formula which used daily. Hav ZX = Hav LHA Cos Lat Cos Dec + hav( lat diff Dec). And many more. JS

[j.sabourn]

Another good one for the layman who wants to know how far the visible sea horizon is, 1.15 times the square root of the height of eye ( in feet) equals the distance in nautical miles. JS