Re: Shaking off the rust
Subject: Re: Shaking off the rust
From: Young, Derrick (youngd@XXX.XXX)
Date: Mon Jan 31 2000 - 13:36:40 EST
Bob, At the target waypoint, I would use the DR points from the planning
track. BUT I don't use a GPS so I would have to bow to someone else that
does.
derrick
> ----------
> From: Bob Hendry[SMTP:bhendry@XXX.XXX]
> Reply To: Navigation Mailing List
> Sent: Monday, January 31, 2000 12:28 PM
> To: NAVIGATION-L@XXX.XXX
> Subject: Re: Shaking off the rust
>
> Hello Derrick
>
> On 31-Jan-00, you wrote:
>
> > Rick,
> >
> > The problem is that you use DR for planning purposes. By definition, DR
> > plots do not take into account variation, currents, winds, sloppy
> steering
> > or any of the other items that impact the course that is steered. In
> > addition, according to Bowditch and others, you should plot everything
> in
> > true on the chart. So, you don't plot the course taking into account the
> > variation (local/regional magnetic differences between true/magnet
> north)
> > or deviation (magnetic changes based on your vessel).
> >
> > Now, you can take each of these elements into account and have a revised
> > planned course on your chart. But that is not a DR plot. When you steer
> > the revised plot, you will still have to take into account the variation
> > and deviation, current, winds, sloppy steering and the other items that
> > impact the course actually.
> >
> > derrick
>
> Thanks everyone for your advice - I think the cobwebs have started to
> clear
> away but, there is a hint left so let's state the problem in another way.
>
> (1) - My chart shows "Variation 22 degrees 45 minutes W (1992) decreasing
> 2
> minutes annually.
> (2) - I have a Deviation Table compiled for my boat.
> (3) - I can determine the Lat and Long of a number of waypoints from the
> chart.
> (4) - TVMDC will be used to plot the course from one waypoint to the next.
> (5) - What do I enter as a waypoint position into the GPS? Do I use the
> True
> position as taken off the chart?
>
> StillRustyBob
>
