NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: What do offshore recreational navigators really do?
From: Lu Abel
Date: 2005 Jun 6, 10:03 -0700
From: Lu Abel
Date: 2005 Jun 6, 10:03 -0700
Joel: What you relate is what a "good" offshore navigator might do -- pre-plan sights, try for a true fix rather than LOPs, etc, etc. But there's "good" and there's "good enough" and there's "common practice." I was interested in the "common practice" end of things. Lu Abel Yourname Here wrote: > Some further comments. > > What I meant to say when I referred to yachties was that a person's > training would dictate how he spaced his sights throughout the day, what > he chose to shoot, and how frequently he took them. > > Also, I failed to respond to the questions about shooting from small > craft. These are not in order of importance, but should improve the > accuracy of your sights from that platform. > > Plan you sights beforehand, and use precalcualted altitudes and azimuths > when appropriate. > > 1. Select a compfortable and secure spot where you are well braced so > you don't have fear of your own safety and be standing. > 2. If possible have a time keeper record the sights > 3. Only shoot from the crest of a wave, never the trough > 4. Take 3 sights in sequence of each body and average the results. > 5. When doing stars, shoot away from a setting sun first in the evening, > and towards a rising sun first in the morning. > 6. Check your index error at the end of daytime sights and before taking > twilight sights. > > In case you were wondering, we did not have a SatNav, Magnavox 4102 or > otherwise on board. > > Joel Jacobs > > > -- > Visit our website > http://www.landandseacollection.com > > > -------------- Original message from Lu Abel: > -------------- > > > > Henry Halboth noted the tradition of 0800, 1200 and 2000 position > > reports to the captain of commercial and military ships, along > with a > > tradition of a noon sun shot. I'm 100 years ago one could also have > > seen several sextants on the bridge wings of any such ship at > dawn and > > dusk, trying to bring down as many bodies as possible to get a > perfect > > "pinwheel" fix. > > > > These navigators had an awesome responsibility of keeping safe a > very > > expensive ship with hundreds of people aboard, so I can certainly > > understand their meticulous behavior. They were also navigating > large > > ships with long turning times and deep draft, so "whoops, there's a > > hazard, hard alee" wasn't an option as it might be on a small! er > > recreational craft > > > > A year ago or so someone told me (and, unfortunately, I don't > recall who > > it was, so I can't go back for more details) that a recreational > sailing > > magazine had polled recreational sailors who had made long offshore > > passages (including quite a few circumnavigators). Of those who > > regularly used celestial, the vast majority reported that they > simply > > took morning, noon-ish, and afternoon sun shots and advanced the > > resultant LOPs. No star shots, no fussing at dawn and dusk, just the > > sun. While I didn't question my friend, I'd assume these folks might > > also take daytime moon shots. > > > > I suspect their theory was that in the middle of the ocean, knowing > > position to a few dozen miles was more than enough. I also note > that in > > a bouncing small craft, taking a sight with any degree of > accuracy is > > extremely difficult. > > *> Comments? Especially from anyone on this list who has made long > > offshore passages on a small craft? * >