"Joshuall" wrote in message
...
This is kind of a follow up to Dave McConkey's question about sonar. I use
it, but know I'm only scraping the surface. I plan on ordering the video
from Bass Clazz, but am wondering if someone can answer a question first.
I may have asked this before, not sure.Ok here it is.

So I'm idleing along and watching my sonar graph and see all the fishies
moving across the screen. . . . so i STOP my boat. . . but the screen is
moving. How come? I mean if the boat is still shouldn't the screen show
the same thing over and over again ? For instance if I cross over a brush
pile shouldn't the brush pile just stay there and not move off screen. All
very confusing to my old simple brain, but somthing I've not been able to
figure out and a question many first timers n my boat have asked.

as usual thanks guys.


Hi Josh,
The picture on your sonar is constantly being updated, regardless of the
boats movement. If you are sitting still, and a fish swims under the
transducer cone of coverage, it will then register a fish coming from the
right side of the screen, moving slowly to the left. That side of the
screen contains the freshest data, and is what is currently under the boat
at that given moment. If the fish stays under the trandsucer, it might show
as a line of fish, at a constant depth. this also works to give you a
little history about what you have just passed, vs what is coming up at that
moment.
The movement of your boat seldom equates to what you see on your screen.
When moving quickly, what you may be seeing on the screen is typically long
gone behind you, since the screen needs a little time to update. You can,
on many depth finders, adjust the scroll speed. This will feed you
information about what is directly below your transducer much quicker, but
will still not necessarily keep up with what is going on at a much higher
speed.

Hope this helps a little...
--
Andrew Kidd