NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: the answer...?
From: Joe Shields
Date: 1998 Sep 29, 07:59 EDT
From: Joe Shields
Date: 1998 Sep 29, 07:59 EDT
I agree, "around noon" the sun's altitude is changing relatively very little, so you can get a good latitude fix even if the timing of your observation is off a bit, but all attempts on my part to determine longitude by pin pointing the exact time of meridian passage has been a lot of work and squinting for dubious results. Better to catch the sun near rising or setting for a good longitude fix. Of course my experience is just with a cheap Davis sextant using an artificial horizon. Ocean navigator wannabee -- Joe Shields ---Russell Sher <rsher@XXX.XXX> wrote: > > You can keep the armour off for my answer Joe, perhaps just move up to give > me a place to duck behing your shield !.... > > I can identify with your comment - perhaps our more experienced navigators > would not agree, but yes, I have found that it is often subjective - even > standing in the garden trying to shoot a LAN sight onto the garden wall > (just for "finding highest-altitude" practice) can be difficult and this was > in an ideal environment. > > regards > Russell > > > -----Original Message----- > > From: Jim Manzari [SMTP:manzari@XXX.XXX] > > Sent: Monday, September 28, 1998 8:13 PM > > To: navigation@XXX.XXX > > Cc: Russell Sher > > Subject: Re: [Nml] the answer...? > > > Jim wrote... > > > ...I consider myself to be a reasonably experienced (celestial) > > navigator, but I am puzzled by the problem. The only explanation that > > I can think of, is that you were on a heading directly opposite to the > > sun (I confess that I am not familiar with the geography of the area > > between Mauretania and the Schedlt) and thus the sun appeared to be > > decreasing in height but still approaching your meridian. > > > > And now, I have to add a bit of my own opinion regarding the noon sun > > shot. Before I commence, put on your armour, get your daggers > > ready for I am about to utter a bit of heresy. > > > > The noon sun shot is overrated. It's beauty lies in the simplicity > > of the calculations required to obtain one's latitude, but that is > > where it ends. One can easily take a few quick observations at > > "around" noon hour, reduce the sight as normal and plot the resultant > > east-west LOP on your chart to obtain your latitude. This method is > > particularly useful at high latitudes where the trajectory of the sun's > > passage tends to be fairly flat and determining the exact moment at > > which the sun reaches its maximum height can be somewhat subjective. > > In the winter time here in Iqaluit, I have sat outside, freezing my > > tail off, for up to 45 minutes, waiting for the sun to reach its > > maximum height of 3 degrees above the horizon. > > > > Even in the mid-latitudes, I have seen people up on deck taking > > observation after observation, trying to determine the exact moment of > > meridian passage, and even after all of that, there is no guarantee of > > a satisfactory result; I have rarely seen two people obtain the same > > numbers. I am not suggesting that the noon sun shot should be > > discarded - I still like to perform the operation - but it is not the > > be all and end all. > > > > Ok, allow me to put on my bullet-proof suit....fire away folks! > > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= > =-= TO UNSUBSCRIBE, send this message to majordomo@XXX.XXX: =-= > =-= navigation =-= > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= > _________________________________________________________ DO YOU YAHOO!? Get your free @XXX.XXX =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo@XXX.XXX: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=