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This post has several parts so bare with me please.  If these subjects came up before I have not seen them.

1.    I just learned that the 2017 PRACTICAL NAVIGATOR (Bowditch) is available.  I downloaded it here and looked over a few chapters - it's really a wonderful piece of work..  If a young person was only interested in the sea this pub would give him everything he needs to function as a well rounded sailor in several disciplines.  There is so much information the format now includes a second volume.

2.    I know this forum is about CN, but forum members might also be interested in the other arts of navigation as well - I am, anyway.  However, I'm having trouble finding good examples on how to use the Haversin tables.  I know what a haversin is and the actual formula to find distance between two points, but an example of table use has not come to my attention... Has anyone a clue??

3.    I dont know how well I can explain this, but the calculator in my cell phone (CP), which includes trig functions, does not arrive at the same answer as my electronic calculator or trig function tables.  I have been learning, for the first time, how to use these tables as well as log tables with great satisfaction and fun, but my CP calculator really threw me for a loop when the Sin, Cos, and Tan functions spit out different numbers than what the purpose-built electronic calculator or tables say. 

For example:  Sin 40

Scientific Calculator - .64279  (rounded up)
Trig function Table -  .64279
Cell Phone calculator - .74511

I can find no options in the Cell Phone calculator which might give me a clue as to why the numbers are not the same...  Any Thoughts???

4.    I would appreciate if anyone could give me a few plain examples on how to use the traverse tables.  Meridional parts and conversion, Log of trig, and Amplitude tables also give me trouble...  I have no idea as to their use.

I may not be much of a navigator or mathematician, but its not for want of trying... :) My goal is to acquire the same skills as those navigators who plied their trade before the advent of batteries and electronics. Dont get me wrong - I appreciate the modern convenience of GPS and all the other cool navigation stuff, but give me a Gunter scale and some tables to occupy my free time and Im as happy as a sailor with a beer in one hand a cute girl in the other.

Thanks in advance
joe

Joe,

Thanks for telling us about the updated Bowditch.

As to Haversins, can't help you much about that for finding the distance between two points. I use this formula for that;

Distance = 90 – Sin -1 (sin(Destination latitude) x sin(Your present latitude) + cos(Destination latitude) x cos(Your
present latitude) x cos(Difference in longitude between Your Location and Destination Location)

Multiply answer by 60 to get Nautical miles.

The "Sin-1" means arc-sin.

A Casio calculator is the only calculator I use- cellular phone one isn't convenient or easy.

Are you trying to find a Great Circle route and waypoints? Pub. No. 229 presents a way to do that.

As to electronics. Ugh, yesterday I was trying to tighten a bolt on the boat trailer hitch and needed the ol' trusty flashlight. Would the batteries work?! Of course not! I was "on the hard" but was a' cussin' like a sailor.

Lou

(08-04-2018, 11:57 AM)LouisC Wrote: [ -> ]Thanks for telling us about the updated Bowditch.  

 Distance = 90 – Sin -1 (sin(Destination latitude) x sin(Your present latitude) + cos(Destination latitude) x cos(Your
present latitude) x cos(Difference in longitude between Your Location and Destination Location)
 
 As to electronics.  Ugh, yesterday I was trying to tighten a bolt on the boat trailer hitch and needed the ol' trusty flashlight.  Would the batteries work?!  Of course not!  I was "on the hard" but was a' cussin' like a sailor.

Lou

I thought perhaps 2017 Bowditch might be old news.... your welcome

Your formula seems similar to the one for finding Hc.  Ill try it for fun, but I still want to learn the haversin table as well as all the nav tables no longer popular.

As a side note; last week one of my English students volunteered to work long (5 significant digit) math problems by hand while I used the log tables.  I consistently worked the problems in half the time with fewer errors.  The log tables work well.

I read that with distances of <600 miles the difference between the great circle and mercator is insignificant, and even at the longest distances the difference is still only about 4 percent; which might be significant in aviation terms, but to ships at sea very little. 

I laughed at your loose bolt experience; "...cussin like a sailor." 

While in the Navy, especially at sea, I always carried a flashlight on my hip in a Velcro loop holster for emergencies - and I made triple sure it was working (the idea of being caught below decks in a darkened ship scared the bejeezes out of me).  Nevertheless, I went to use the flashlight in my tool box a month ago and it was flat dead... I still haven't replaced the batteries..  Its funny how our priorities change.

joe