We all have seen the nice moon HP tables provided by NAUTICAL ALMANAC website, but I wonder if you know that there are two versions... the second of which I can't make heads or tails.

The copy of the Almanac moon HP table - the one with separate lists for upper and lower limbs - makes good sense once you get used to it.  However, there is another version tacked on the end of the Sun/Star/planet increment download that boggles the mind.  Not only are the numbers incomparable with the Almanac HP table, but there are no upper and lower HP divisions - only a single number.  That single number does not compare to UL or LL corrections noted in the Almanac version. 

On the same page with the errant HP table is a Refraction table that I like to use with Gunter shots, and the DIP table seems sound, but that HP table gives me the willies...  Until someone can tell me how to use it so the numbers match the Almanac version Im not going near it.

joe

Anyone who has read Table 4 instructions will agree that they are most confusing... I think I know why - there is an error in the document.

Here is the problem:  Read along if you have table 4 instructions handy.

OT = Jan. 18d 04h - 7h = Jan. 17d 21h.    (so far so good)

Main Table, Jan. 17d OT, E 2 33 (- 5)          Dec. S 20 51 (- 12)    (still good)
Table b for 20h OT             - 4                             - 11             (PROBLEM)

AH- here is the problem; the 20 should read 21 as per the OT line above.  If the OT was in fact 20, the DEC correction -11 would change to -10)?

Jan.17d 20h OT, corrected E 2 29       (SAME PROBLEM)

Here again the 20 should read 21 as per the OT line above.

These small errors made my life a living hell as I tried to figure out from where they got the 20.....  

After realizing the error and a few practice problems I compared the GHA and DEC with an Almanac, I noted only a small difference between the two; less than a minute.  That's not too bad for a few sheets of paper good for almost two score years of Sun GHA and DEC data.

joe

OK, so Im not a big TV fan.  I have not watched TV in many years, but this is not to say i dont like movies. If provoked by a good title or reputation Ill force a DVD into the machine, make some pop-corn, open a cold bottle of soda, and immerse myself into a world designed by some obscure producer. 

A year ago or so I found a movie on the internet made just for me.  Ive probably watched the goofy thing 20 times and I keep going back for more.  The acting is superb, the set is vivid and appropriate, the special effects are adequate, and the music score is pleasant. 

The Movie LONGITUDE  has been my favorite for quite some time now and has displaced THOSE MAGNIFICENT MEN IN THEIR FLYING MACHINES (another wonderful British film) as my go-to video for perennial entertainment. 

LONGITUDE is quite a long movie and seldom, in my view, slows down.  My only weak criticism would be of the actor who plays John Harrison's  son - the eldest. (there are two actors playing the part).  The one who plays the son as an adult is a bit of a ham. Several times he comes close to spoiling what might be one of the greatest made-for-TV movies ever created...  Another great British movie  is called THREE MEN IN A BOAT. 

Watch LONGITUDE on Youtube soon - you wont regret it.  There are several copies of this movie on the internet - I think Ive given you the best one. Its in two parts so when you see the credits half way through dont freak out... the second half of the movie starts almost immediately.

Joe

I have a dilemma... two great looking sextants at good prices (about $250); I don't know which to choose.

The Freiberger Sextant has a lightweight aluminum alloy frame, a 4 x 40mm scope, a wooden storage case with instruction manual.  The horizon mirror is serviceable but needs replacing.
 
The Tamaya 833 has a 7x35 scope and is in good shape, no storage case.

They both appeal to me.

Which is the better sextant?

joe

I am confused as to why there is HP data posted on the daily pages for venus and mars.

If and when, would be my question, do we use this correction???

joe

What exactly is table 5 used for???

Perhaps this subject has arisen before, however it might shed an interesting light on choice.

Given the fact that in this day and age we have the absolute best navigation tools ever devised, we, as purest CN lunatics, long for technology of bygone days -  nevertheless we still welcome the chronometer as a standard piece of gear. 

Granted the chronometer greatly  improved the accuracy of early navigators, Slocum - unable to afford one - used an old tin clock.  So how did he navigate? There was no WWV or radio beacons, etc.  The answer - The lunar method.  He didnt need a chronometer, and although a goat ate his charts, he made the trip without much difficulty.  Of course the lunar method is more cumbersome mathematically than our present day single shot table methods, but he still needed a sextant - and circle the globe he did.  HOW COOL IS THAT?  I once (ignorantly) used nothing more than a road map to navigate the great Yukon River in Canada by canoe.  The HMS Bounty captain, after mutiny, had but a very limited supply of NAV tools to usher his surviving crew thousands of miles to safety - avoiding known islands of inhospitable natives - without chart table or enclosure within to work.

My question for you:  What is the absolute minimum navigational equipment list and navigation technique you might feel comfortable with if circumnavigating the earth solo or with a minimal crew?  (include any and all paper references, tools, recording implements (pencils etc.), space requirements, support equipment (table, chart room, etc), and lighting. Exclude supplemental emergency devices or implements.  

Have fun

joe

When you plot your TOWARD or AWAY distance, do you account for the change in distance between degrees of longitude? For instance, if you were plotting T or A of  10' east to west, do you plot it at the full 10 nautical miles or would you compensate for the narrowing of longitude lines away from the equator? Whereas when plotting T or A north to south you would plot 10' as 10 NM.

I have been using full values when the azimuth is within about 25 ° of E or W and compensating for greater angles. Not sure if it's helping or hurting or even makes a difference.    

I hope the question makes sense, I've had a couple of glasses of wine. :)

The other day I mentioned to my students that before the advent of phones, internet, electronic computers, gps, PACMAN, airplanes, automobiles, household electricity, indoor plumbing, and disposable diapers there was a way for travelers to mark their location on the globe by using celestial navigation techniques - which i explained in the simplest of terms.... The students paid polite attention and only wrinkled their noses at the bigger words, but I dont think they believed me. 

Joe

I have Bowditch Practical Navigators from 1800s.  1807, '39, '41, '54, 1916, '95, and 2003.  They list instruments and nav tools in which I am interested.  The Sector and Gunter scale are two math aids that provided skippers with logarithmic and trig scales to facilitate navigation. 

 If any of you have knowledge or references for these and other old world tools Id be pleased to discuss them.  Other tools might be the Gunter Quadrant, back-staff, octant, plane scale, full circle brass protractor and dividers, barometers, speed measuring devices, depth sounders, even their paper charts interest me ... How did they protect them from damage or rot?   

Everything used from the 1800s and earlier has my attention (no batteries)... i want to learn to use those old tools.  I was interested to find out that they used a depth sounding device made of glass tubing that was painted inside with a material that changed color so that as the water pressure at depth squeezed water further up the tube the depth could be recorded.... soooo cooool   ... Ay?

Those 1800s sailors were not as ignorant as I thought...  Maybe we dont give them enough credit... I know I didnt until I started reading those old Practical Navigators.

joe