Hi Sam

Have a look at my web site for Sea fishing boats and equipment under Fish
finders
http://fishing_boats.tripod.com/

I have put an article on there which helps explain single and dual
frequencies.

Regards

Dave


"Sam Matthews" wrote in message
om...
Hello all,

I'm new to the world of fish finders. I used a simple one on a couple
of trips, but the more I stared at it the more I realized I had no
idea what it was trying to tell me.

First of all, I coudn't for the life of me understand why everything
was *always moving*. Even when I brought it ice fishing, and put it
on the surface, it showed the bottom as if I was wizzing by in a speed
boat. After many months I realized the mistake I was making.

The temptation with these things (and I hope I'm not the only one) is
to look at the pretty picture, and imagine that - "this is what the
bottom looks like". However, it is not like that at all. It is not a
"snapshot", but is really a graph, a log, a history of signals passing
across the screen.

The new unit I just got (Humminbird 565) has helped me to understand
that. It has, along with the graph, a "flasher" type reading to the
far right. It is easy to tell from this - where the historical
reading is comming from, that which is always panning accross the
screen.

One of the reasons I got this unit is - I do a lot of shallow water
fishing (rarely over 20 feet). I thought this unit would be ideal,
for the wide coverage that it gives. The narrow beam covers 20 deg,
and the wide beam covers 60 deg.

What I am now wondering though is - and the real subject of my post is
- can I really make use of it?

Lets say I'm sitting in 20 ft of water - perfectly still - and
suddenly a fish enters the wide beam of the transducer. Regardless of
where that fish enters the sonar circle, I'm going to see it show up
on the right the screen - and pan left. What do you do - start
casting around like a mad man? Are there any tricks to determining
*where* a fish is?

This unit says that - it will show a fish in the wide beam as a
"hollow" symbol, and those in the narrow beam as a solid symbol. So
at least you have a guess....I guess.

Why is it so hard to show a real-time "snapshot" of what is going on
down there - like a camera. If a fish swims in from the left, you see
it on the left of the screen - not on the right and zoom across. I
understand that if a fish sits directly below the transducer, it will
show up as a black line all accross the screen.

Thanks,
Sam Matthews