Robert B. wrote:
> DMS is your friend if you're ever humping around in the woods with
> nothing but a compass and a map.

You must have a pretty fancy compass and an amazing ability to follow a
bearing if less than a degree makes any difference to you in the woods.  I'm
a hike leader with the Appalachian Mountain club, have used map and compass
in the woods on a number of occasions, and have even taught it to beginners
in formal courses.  Plus or minus 1 degree would be amazingly accurate.
Most real hiking compasses aren't even marked that accurately, except the
silly fancy models some stores try to sell to those who don't know any
better.  My compass is marked in 5 degree increments, and that's just fine.

> Dead reckoning (on foot, at least)
> is based in part around the DMS system, and knowing how many "paces
> per second" your stride is.

Maybe if you live on the plains or stick to pavement.  Even on regular
trails, you usually just guess your speed in terms of minutes/mile, then use
a watch to get a rough idea of how far you probably traveled.  Of course
this is all out the window when bushwhacking thru sporadically dense
vegitation.

> IIRC my pace count is right around 45
> paces/second of latitude (also conveniently 45 paces/100 feet).

So you're honestly telling me you count paces to measure arc distance
travelled!!?

> I
> suppose you could do it using decimal degrees as well, but trying to
> compute that in my head would be a little tough.

Even if you did this, it would only work when going north or south, unless
you want to do the mental correction for the shortening of longitude
depending on latitude.

> This system translates nicely to GPS, and allows you to go on week-long
> expeditions on a single set of GPS batteries, by just using the GPS
> for checking up on your position.

OK, but you started out saying DMS was useful with "nothing but a compass
and a map".

> Admittedly, the dead reckoning system also uses standard distances,
> such as miles and km.  But these also transfer much better to the DMS
> system (and human memory).  For example:  if you're 1 mile off
> course, this is roughly one minute.

But what does that tell you, when you've got just a map and compass?  "One
mile off course" is already what you want.  What you really want to know is
where you are and where you want to be on the map.  From that you set your
compass to the bearing to follow.  The compass is set by using the lines on
the compass and the lines on the map.  The units the compass is marked with
don't enter in at all except when correcting for magnetic declanation.


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