Ah Arild.... Are you trolling here or do you really want to know?

Predictor Line:

Has many advantages in ENS.  Aside from those already mentioned here,
one can center the chart on the predictor line look-ahead point.  That's
a great boon.  On a fast moving vessel one of the complaints is not
being able to see far enough ahead on the chart when the vessel is
centered on the chart.  Some folks run two zoom views simultaneously and
switch back and forth.  But changing the chart to be centered on the
predictor moves the vessel to the bottom area of the chart allowing the
full screen look ahead dynamically moving with the boat.

Another is the obvious sound the alarm when the predictor reached the
next waypoint.  When traveling long straight legs it's nice to be
reminded that you are coming up on a turn or change.  This is especially
true if you allowing the computer to steer the autopilot.  IOW, do you
really want to make this next course change that I (Mr. computer) will
do in 5 minutes?"

Another is "sound the alarm when the predictor reaches any barrier".  On
our route planning we put circles around any shoals or rocks close to
our route and barrier lines across any areas where one could go too far
(miss a turn) into shoal waters.  So when the predictor gets to these
dangers 5 or 10 minutes before we do, I am alerted.  Same deal when
entering a narrow passage.  I might put temporary barrier lines up on
each side to insure I don't wander into shoal water.

Sometimes we will put a point on an ENS chart where there is a location
of interest.  When the predictor reaches that point, we pop up the icon
and there I have written a little summary of the reason why this is an
interesting location.  For example, throughout the inside passage there
is a rich history of settlements that are no longer there.  Instead of
passing them by our ENS will beep and I pop up my summary (which
includes book and page number references) and we will have 5 or 10
minutes to dig out the book and decide if we wish to stop, linger and
explore.

So much for predictors.

One of the things I forgot to mention which is another huge advantage of
ENS is the ability to give the helm to an inexperienced driver.  With
the knowledge of the course and heading and an admonition to keep the
boat on the line, one can safely conclude that if the helmsman follows
your instructions, you will not run into shoal water.  You can actually
relax.  You can sit back and use your eyes to look about instead of
constantly checking on your helmsman and estimating position on the
paper chart.

ETA / Fuel Mileage

I think somebody mentioned that it would be nice to have this work
without GPS input.  It does.  After you have entered you mpg at various
speeds and entered you speeds per leg of route the computer will
calculate these figures.  Obviously it cannot adjust for changes you
might make during the route which is the advantage of the dynamic GPS
interface.  It's a simple one click to switch between these modes.

I liked the comment about manually running the boat's autopilot with no
GPS interface at all and just tweaking the course manually to keep on
the route line.  That's the best way to use this in confined areas IMO
and works well on long runs too.  Just set the computer to beep on a
cross track error and tweak the autopilot course knob to get you back on
the line.

Computer Horsepower:

Don't get lulled into thinking you P200 with 64MB of RAM is just fine
for ENS.  Like any high graphics applications, ENS systems can use all
the power you can afford.  I'm not saying they wont run, I'm saying
there's running and then there's singing <G>.  Especially if you start
loading your ENS up with points, routes and location data.  It's easy to
get thousands of waypoints and hundreds of routes.  When you do you may
really see your computer bog down.  If you plan on using the trace route
(dropping breadcrumbs) functions, watch out.  10,000 waypoints can be
added in a short time.  Running multiple charts open simultaneously will
really slow things down too.  It's easy to get a bunch of charts open by
accident all hidden behind each other.  Computers are so cheap now.  A
good P4 x 2 GHz x 256mb of RAM can be had for about $900.00 (note I said
a GOOD computer, not a consumer POS computer).  So why not use that
power?

Finally:

What irks me is the references to fiddling with the ENS systems and not
looking out.  That's baloney.  ENS does not require constant fiddling.
It requires the occasional glance.  In fact, as mentioned many times
before, ENS frees the helmsman and lookout to look out more not less.
The perception that some computer geek would rather constantly fool with
the computer and navigation system while underway rather than enjoy the
journey and keep a lookout is spurious at best.  It goes back to the
same old argument that standing in the rain in a sailboat cockpit and
navigating by feel and thumb is the only "real" sailing and that
somebody sitting in a heated powerboat with a computer navigating the
vessel is not a "real" sailor.  For me that runs right up there with the
argument that putting a telephone in every house would corrupt our minds
(or whatever that argument was when telephones were introduced)<G>

Joe Engel
Marine Computer Services, Inc.
Portland, Oregon

-----Original Message-----
From: Arild Jensen [mailto:elnav@uniserve.com]
Sent: Thursday, March 13, 2003 6:22 PM
To: trawler-world-list@lists.samurai.com
Subject: TWL: Electronic Navigation techniques ( Was Nobeltec / Maptech
$$ value)

-----Original Message-----
REPLY
It seems to be an unspoken  assumption that we all use  the electronic
charting systems in about the same way.

But is that true?  Somehow I doubt it!

cod

(SNIP) This guy literally  tried to program a route from his slip to the
slip at a popular  waterfront restaurant forty miles away. The forty
mile route  required 93 waypoints and some of the legs  were less than
100 yards long through rocky channels  about fifty feet wide. And this
was back before SA was removed. Nor did he have Differential GPS. Just
the plain old kind with a plus minus tolerance of 100 meters ( >300yds)

Sounds like a good "Darwin Awards" candidate to me!

                               Regards.....

Phil Rosch
Old Harbor Consulting
M/V "Curmudgeon" Marine Trader 44 TC
Currently Moored in Fort Pierce, FL

"Twenty years from now you will be more disappointed by the things you
didn't
do than by the ones you did do. So throw off the bowlines. Sail away
from
the safe harbor. Catch the trade winds in your sails. Explore. Dream.
Discover." - Mark Twain