On Sep 27, 4:57*pm, "Capt. JG" wrote:

Sure... explain away!

I'm not a huge fan of radar...

I thought SF Bay was quite foggy. Am I wrong? Back when I was saying
I could do fine without radar in Maine I would also think, "Now if I
was someplace like SF Bay..."

I looked at the small stand alone radars of size and power draw
appropriate to my boat and learned that Garmin has done a clever thing
(muc has it pains me to say since there is much I hate about Garmin in
general). Their radars do all the signal processing up in the radome
and then turn it into a signal that runs along a standard Cat 5
computer network cable like the one that probably is plugged into the
back of your computer. A clever person could certainly hack software
to make it display on a lap top. Most of their chartplotters accept
this signal. So, for less than $200 more than a stand alone unit, I
could buy a radome and a 3205 chartplotter with charts for the entire
U.S. preloaded. I essentially got a second larger and more
sophisticated chartplotter for free and a color display instead of the
BW of comparably priced stand alone radars. Instrument space is
precious on my small boat so it was also nice not to have yet another
box.

The best thing about the set up is that the radar display can be
overlaid on the chart with the GPS position. This is a huge
improvement in situational awareness. You can figure out almost
instantly whether a blip is a buoy or a vessel as opposed to going
back and forth between a dedicated radar display and a GPS or chart
transferring ranges and bearings. When you are sailing single or
shorthanded, these workload savings reduce fatigue and improve lookout
and attention to other navigational issues.

It's very difficult to run a proper radar plot in close, complex,
waters such as along the coast of Maine. Radars of this size are not
very conducive to plotting directly on the screen although some people
do it. There are enough asterisks scattered around Maine waters that
I'm reluctant to clutter up my screen with marks as well. The chart
overlay is a great plotting substitute. You can see by watching
soundings and other landmarks if a target is just wandering around
randomly and is probably a lobster boat or maintaining a straight
course and make a good estimate of speed. If it is close to
maintaining a constant bearing, it will be pretty obvious. Switching
to full screen radar mode gives your all the standard tools which I
some times use but I have to use them a lot less because I can rule
out most targets as a CPA danger just from the chart display.

There's much more of a learning curve than I expected. I spent the
first week or two thinking "Why did I spend all this money?" I
thought the overlay was pretty useless because it was so hard to find
the little red targets in the clutter. The brain trains. Now, I
little red spot pops up and my brain zeros right in on it from six
feet away at the helm. Working with it a lot in clear weather, I
developed enough trust to do my singlehanded radar running on
autopilot trusting to the advance warning. The straighter course the
autopilot can keep, (at least when I'm standing radar watch) makes the
whole picture clearer. I have the dodger in my hand and it only adds
a couple of boat lengths to the distance in which I can spring to the
controls and do a full stop or 180 turn which is much faster in my
boat. As I said, I wouldn't sail without it now.

--
Roger