T&T: radar return

[Scott E. Bulger]

David, you made some observations and asked some questions.  I'll share my
limited experience, hopefully it will be of some value.  First, my
qualifications are that I've spent about 1,000 hours in the last year using
my radar.  I think I've gotten pretty good at tuning it.  When we started
our trip I couldn't seen pangas off the coast of MX, by the time we got to
Central America I could easily adjust the set to see pangas and other small
craft (dugout canoes included).

You observed:  In the past, such buoys also left a strong signature on the
screen.

Scott suggests:  When you use your RADAR in auto mode the various software
functions combine to attempt to deliver the best overall picture.  If you
were in the presence of rain and other clutter it's likely the auto features
were being brought into play to improve the overall picture, but resulted in
reducing the return of items you previously viewed with strong returns.
This is not unusual, nor is it a defect or problem with the auto features.
It's the result of the software trying to deliver the best overall picture.



You also commented:  In the gathering darkness and keeping my eye on where
we
were going, I did not try to adjust the set. I understand radar theory,
but am no expert on it. We generally just leave the set on the standard
factory default settings and run it on auto mode

Scott suggests:  You made a great decision.  With darkness approaching the
last thing in the world you needed to do was mess around with your radar!!!!
Good choice!  Now that this is behind you, it's a great time to adopt a new
technique, that of using and playing with your RADAR when you don't need it.
The best time to learn the effect of radar adjustments is when it's bright
and clear out, and there is no danger around you.  The worst time is when
you REALLY NEED your RADAR.  

Scott continues:  I'll share what I have learned about adjusting my RADAR.
First I'll say that I'm not expert, I'm only sharing my experience and
welcome others to comment or correct me if I misstate any features or
techniques.

Overall, first I feel the need to comment about some advice given in
response to your question.  The advice included the suggestion to start by
adjusting your RADAR to the longest distance it supported, adjusting the
gain and then reducing the distance without going back to adjust gain.  In
my experience this doesn't work.  There are significant differences in the
impact gain adjustment has based on range selected.  Gain is the one thing I
continually adjust for changing conditions, including the range selected.

Range is in and of itself a big point of question and discussion.  I was
really surprised the first time I crewed for Capt. Mike on a delivery up the
coast.  While I was messing around with the RADAR Mike commented that for
what we were doing at the time, a setting of 3 miles was the farthest he
wanted the RADAR set to.  I was confused, thinking having it set farther out
would be give us much better visibility to things coming close.  He went on
to clarify that he sets the RADAR up so he can get the best visibility for
boats that present the most risk in close quarters.  Remember, he's
balancing additional factors, including crew with questionable experience
and skill keeping a watch at night.  Until he knows the crew's skill level
he has to factor in other safety issues.  Anyway the point he went on to
make was that if the RADAR was set to farther ranges the operator could
easily miss small targets that are in close and need much more attention
from the skipper.  So, in my experience we spent 90% of our time with the
RADAR at 1 or 3 miles.  The most significant exception to this was when we
brought the boat from Panama to FL.  Since we were in the open ocean we
found we could adjust the set to much larger distances and it did a really
good job of painting the ships at 12 and even 24 miles.  In summary, 1 to 3
miles is something you should spend a lot of time getting good at adjusting.

Features,  as you know your RADAR has a number of adjustable features,
including RANGE, GAIN, AUTO, Sea Clutter and Rain.  In addition there are
other features that can be employed to enhance your display, such as ECHO
averaging and strength, Trails, ECHO duration and NOISE rejection.  Here is
where my advice is based solely on experience and I can only tell you this
is what works for me!!!  I'm sure others will disagree.

1.  I first turn on the set and go into setup to select a few features I've
come to know I will use.  I turn ON Noise Rejection.  On my set (Furuno) the
Noise Rejection is a feature that cancels out interference from other
RADAR's transmitting in the area.  It's very easy to see the effect of
having it on or off.  The screen will be covered with specs when off, and
cleared of them when on.  This assumes there are other Radar's transmitting
in your area. As I have been traveling with other boats a lot, this has been
the case 90% of the time.  The manual warns you that this can reduce
sensitivity to small targets, so if you are sure your alone in the area,
turn it OFF.  Next I turn ON ECHO Averaging and set to a value of LOW.  I
use to turn on ECHO trails, but now I just use ARPA to track the targets I'm
interested in.  However for a long time I did like to have Trails turned on.
I set the RINGS to medium brightness so I can easily see the distance
scales.  

2.  Next adjust the RANGE to the range I'll be using 90% of the time, 1 or 3
miles.  I increase the gain to the point where boats, marks, shoreline
features really stand out, BUT you aren't getting spurious returns from the
water or RADAR targets that meld together or aren't crisp.  It's hard to
describe, but you'll come to know when you have too much gain.  

3.  IF there is wind on the water, or Rain I'll next go after the Sea
Clutter or Rain adjustments.  I'll usually only do this after the boat has
pulled away from the land mass, as I've found that adjusting these values
near large land masses, or when 1/3 to 1/2 of the screen is blocked  or
fully filled in results in poor adjustment.  Seaclutter should appear as
arcs to the windward side of the boat.  They usually fan out like a slice of
pie upwind.  By slowly adjusting the seaclutter you should see it slowly get
less and less obvious.  I usually don't try to make it all go away, just
reduce it by 80%.  I then do the same thing for Rain.  Rain is something you
really have to be careful about.  It can obscure real targets very easily.
In the Pacific NW it was a great feature for removing the light drizzle you
get so often, but in really heavy rain, forget it.  Best way to learn about
this is to tell the significant other you have to go to the boat on rainy
days to play with the radar!  A great excuse to boat in the winter!

Finally, there are a number of other things you can play with.  For example,
I didn't discuss that the brightness of the screen is important.  During the
day I set the display brightness to full, at night about 2 or 3.  I also use
EBL, VRM, ARPA and other features.  When in the open ocean I use a separate
Chartplotter N up for following the course and have the RADAR on RADAR only,
no overlay.  In the ICW or close to land I'll set both systems to N up and
turn on the RADAR/Chart Overlay feature.  I do this for redundant position
confirmation.  I've never been one to complain that a RADAR/Chartplotter
display is too busy or complicated.  However, when in the open ocean it is
very nice to only see things on the RADAR if it's the shoreline or a target.
If I'm traveling with other boats, and I know they are set to 3 miles I'll
push my RADAR out to 12 every 15 or 20 min.  If I'm in the ICW and see a
weather system coming from the west I'll push it out to 48 miles and crank
the gain all the way up and you get a great weather picture.  You can see
thunderstorms coming from 40 miles.  

Anyway, I hope this has been helpful.  If there was one thing I'd encourage
you to do is go out and play with it.  If your concerned about getting it
back the way it is, just write everything down if you make changes.  Since
your using Auto you should be able to get back where you are without too
much problem.  Good luck, we are really lucky to have all this great
technology at this time, it sure makes boating safer!

Scott Bulger, Alanui, N40II, Seattle WA
Currently at Liberty Landing Marina in the shadow of the Statue of
Liberty!!!