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This could be an interesting thread.  OK, I'll be honest, although I feel
nervous sticking my neck out. Don't expect Navy/Merchant Marine/Coast Guard
nav procedures on our bridge.  No doubt I'll learn from reactions to this.

Recreational boater, coastal marine tidal waters, 30' twin screw family
power cruiser, two helm stations, and usually steer on the flybridge.  We
never travel out of sight of land, unless rain obscures the horizon in
mid-Strait during a crossing.  We do not range more than 200 NM from our
home port.

1. GPS chartplotter and laptop with track recording, supplemented by radar,
sounder and magnetic compass (one at each of our two helm stations).
2. I keep paper charts handy at the helm station, but we do not have a chart
table, so I keep the charts in big plastic envelopes, each folded to the
portion of water we will travel.  I have a dozen such envelopes.  At the
beginning of each summer I preload them with the appropriate charts, folded
to the area we will be cruising.
3. I do not attempt to plot a record of tracklines or draw bearings on the
paper charts, although I do that on the laptop sometimes.  I never draw on
the paper charts.
4. Sometimes I take rough bearings on navaids or landmarks using our
compass-equipped binoculars, then roughly transfer them with the edge of my
hand to the compass rose on the paper chart.
5. I sometimes jot informal notes in a reference binder that I keep at the
helm station, but I do not formally log periodic positions in lat/long
coordinates.  Just, "1015: rounded Cape Bear, winds SW 15, waves astern and
lumpy with ebb, SOG 8 knots, 2600 RPM".  At the end of each day, when we tie
up or anchor, I save the trackline to the laptop's memory.  I can replay the
trackline anytime to show heading, speed and position.

I've taken all the Power Squadron courses, and I was at the Coast Guard
College in younger years, so I understand formal DR procedures.  But they
are not very practical in our kind of cruising, on our kind of small boat.
I keep the parallel rules, dividers, drawing compass and etc on the boat in
a drawer.  However if the electronics go down then I am prepared to start
using them, and as we cruise along I am always "thinking in DR" as a I
gather information from the chartplotter, radar and sounder, and as I
periodically check the paper charts while steering.  The GPS' trackline is
very useful.  I have worked out deviations for our two compasses, but never
have to steer by compass alone.

Most recreational cruisers in our area are not trained in formal DR
procedures, and some do not even carry paper charts for local runs.  Those
that do often seem to use them the way we use roadmaps while driving a car
on roadways.  I don't know anybody who uses parallel rules here.

"Thinking in DR" is an interesting way to put it, I guess.  Having done all
those laborious DR plotting excerises in course work, I find myself mentally
using those procedures when I look at the instruments or study the wind and
waves to picture leeway/current.  The more one knows about DR, the better
one's position sense.

Jim Thompson
jim2@jimthompson.net
www.jimthompson.net
Outgoing mail scanned by Norton Antivirus
-----------------------------------------

> -----Original Message-----
> From: Navigation Mailing List
> [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Royer, Doug
> Sent: Thursday, October 16, 2003 3:15 PM
> To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
> Subject: DR plotting techniques
>
>
> I would like to ask the members of the list who sail or pilot
> power vessels
> how or what techniques they use to find their DR pos. while underway.I am
> only interested in what methods you use and don't wish to get into a
> discussion of accuracy as yet.
> 1.Do you use paper charts,rules and dividers?
> 2.Do you use mathematical methods such as the following:Lat=Lf + -
> e[S/60(cos T*)] ; Lon.=Lon.f + - e[S/60(sin T*/cos Lf)]
> 3.Do you use chatplotters and gps?
> 4.Do you use a computer or laptop with navigation software and gps?
> 5.Do you use gps only?
> 6.Any other method not listed above or a combination of the above.
> Steven,thanks for telling me your training.In future conversations I now
> have a baseline and know how to frame my questions or discussions with
> you.By the way,thanks for the work you did on the Lunar files.I
> hope to make
> some use of them.
> Jared and Dave,I'll get the brand name of the LED nav. lights
> when I get to
> the yard this week to work on the skiff and post that info.
>
>

   

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