NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Board of Trade exam, 1880s
From: Greg B
Date: 2013 Dec 28, 15:50 -0500
From: Greg B
Date: 2013 Dec 28, 15:50 -0500
Paul,
A good experiment would be to take an existing nav problem someone used to demonstrate a Mq. St. Hil. 3 body fix and
make 3 Sumner lines from it. Its a pain in the neck to do in H.O.229 but I did it once in excel and aside from the time for
making up the spread sheet it took no time at all to generate the 3 Sumner lines. your really just doing 6 time sights; your
solving for longitude twice for each body's Sumner line: using DR (AP) Lat + 10' and DR (AP) Lat - 10' use the same DR Lat
for all problems. Plot the 3 Sumner lines on the same plotting sheet you Plot the regular Mq. St. Hil. solution on and let me
know how you make out the two solutions (Sumner & Mk. St. Hil.) should agree.
~Greg
On 12/28/2013 03:20 PM, Paul Hirose wrote:
A good experiment would be to take an existing nav problem someone used to demonstrate a Mq. St. Hil. 3 body fix and
make 3 Sumner lines from it. Its a pain in the neck to do in H.O.229 but I did it once in excel and aside from the time for
making up the spread sheet it took no time at all to generate the 3 Sumner lines. your really just doing 6 time sights; your
solving for longitude twice for each body's Sumner line: using DR (AP) Lat + 10' and DR (AP) Lat - 10' use the same DR Lat
for all problems. Plot the 3 Sumner lines on the same plotting sheet you Plot the regular Mq. St. Hil. solution on and let me
know how you make out the two solutions (Sumner & Mk. St. Hil.) should agree.
~Greg
On 12/28/2013 03:20 PM, Paul Hirose wrote:
Greg Licfi wrote: > Do you by > any chance have the details of the > problem-so I could try it out? No, I didn't notice any sample examination problems in the book, but I haven't looked through it thoroughly. The old navigation texts online have examples of "old school" (latitude or time sight) and "new navigation" (Sumner) problems fully worked. I think these would be typical of what you'd encounter on a Board of Trade exam. --
