I currently have an inexpensive fish/bottom finder with a 20deg cone angle
and am having very much trouble locating "obstructions" on the bottom where
I fish (in the gulf out of Pensacola). Many of these were points were
converted from Loran to GPS and only go to 2 decimal places, or within
52.8ft. My GPS might be within 10-20ft and the 20deg cone, at 50ft, if my
trig is right, is just over 18ft. Most of my fishing would be in the 40 to
100' depths.
In short, it takes a lot of passes to locate a car body or even a larger
object such as a sunken tug or barge.
I think the Hummingbird Matrix 37 with a 90/20 dual cone or the Eagle
Trifinder with up to a 150deg cone would help locate these wrecks.

Is my logic good? Am I missing something?

If you wore shoes that were 10ft square, would you feel a small hole?
The first thing the "ping" hits returns an echo.
If you have a 6ft "hit" on the bottom & you go over a 7ft hole you will get
an echo from the bottom of the hole.
If you go over a 4ft hole you won't see it.
That's my understanding anyway.
BruceM


"LD" wrote in message
ink.net...
I currently have an inexpensive fish/bottom finder with a 20deg cone angle
and am having very much trouble locating "obstructions" on the bottom
where
I fish (in the gulf out of Pensacola). Many of these were points were
converted from Loran to GPS and only go to 2 decimal places, or within
52.8ft. My GPS might be within 10-20ft and the 20deg cone, at 50ft, if my
trig is right, is just over 18ft. Most of my fishing would be in the 40
to
100' depths.
In short, it takes a lot of passes to locate a car body or even a larger
object such as a sunken tug or barge.
I think the Hummingbird Matrix 37 with a 90/20 dual cone or the Eagle
Trifinder with up to a 150deg cone would help locate these wrecks.

Is my logic good? Am I missing something?

But will the wide angle see the wreck 30-40ft away instead of my current
"sighting" only 9' from center of the cone 50ft down?
LD


"BruceM" wrote in message
...
If you wore shoes that were 10ft square, would you feel a small hole?
The first thing the "ping" hits returns an echo.
If you have a 6ft "hit" on the bottom & you go over a 7ft hole you will
get
an echo from the bottom of the hole.
If you go over a 4ft hole you won't see it.
That's my understanding anyway.
BruceM

Yes, most definately but you won't see any smaller "ups & downs". Because
you will have such a large "footprint", the bottom will tend to be much
smoother instead of hundreds of "ups & downs".
Have you thought of getting something like a Humminbird Wide eye? The have
two different beams built in & you can have :-
1.narrow.
2. Wide.
3. Both.
You just alter which one you want in the menu.

From your example I'll try to explain a little.
If a wide beam has a footprint of 50ft on the seabed & you go over an object
that is only one foot accross, it will look almost like it is 99ft across.
As soon as the object hits the very edge of the beam, you will detect a
shallower bottom. The bottom will appear to be that depth until you have
travelled over the object until the footprint passes it & "drops" back to
the original bottom depth.
Before all jump down my throat, I just want to point out that I'm not going
into "bottom definition" etc, etc, but am referring to the very basic echo
sounders that most recreational fishers etc have.
BruceM


"LD" wrote in message
ink.net...
But will the wide angle see the wreck 30-40ft away instead of my current
"sighting" only 9' from center of the cone 50ft down?
LD


"BruceM" wrote in message
...
If you wore shoes that were 10ft square, would you feel a small hole?
The first thing the "ping" hits returns an echo.
If you have a 6ft "hit" on the bottom & you go over a 7ft hole you will
get
an echo from the bottom of the hole.
If you go over a 4ft hole you won't see it.
That's my understanding anyway.
BruceM

That helps somewhat. I have access to a Humingbird Wide Eye but the
transducer is missing and its maybe 10 years old and the resolution is
"poor". I just downloaded and read the owners manual but it seems to claim
it can see "fish" out to the sides, not read the bottom out to the sides.
Several units advertise the dual beam and show fish symbols either hollow or
shaded depending on if they are in the center "narrow" beam or the wide
angle. Then there's the Hummingbird Matrix 37 that advertises "quadrabeam"
with a split screen (which I think might be easier to visualize, if it truly
shows the bottom on the right or left or in front??)
Thanks for your input.
LD

"BruceM" wrote in message
...
Yes, most definately but you won't see any smaller "ups & downs". Because
you will have such a large "footprint", the bottom will tend to be much
smoother instead of hundreds of "ups & downs".
Have you thought of getting something like a Humminbird Wide eye? The have
two different beams built in & you can have :-
1.narrow.
2. Wide.
3. Both.
You just alter which one you want in the menu.

From your example I'll try to explain a little.
If a wide beam has a footprint of 50ft on the seabed & you go over an
object
that is only one foot accross, it will look almost like it is 99ft across.
As soon as the object hits the very edge of the beam, you will detect a
shallower bottom. The bottom will appear to be that depth until you have
travelled over the object until the footprint passes it & "drops" back to
the original bottom depth.
Before all jump down my throat, I just want to point out that I'm not
going
into "bottom definition" etc, etc, but am referring to the very basic echo
sounders that most recreational fishers etc have.
BruceM


"LD" wrote in message
ink.net...
But will the wide angle see the wreck 30-40ft away instead of my current
"sighting" only 9' from center of the cone 50ft down?
LD


"BruceM" wrote in message
...
If you wore shoes that were 10ft square, would you feel a small hole?
The first thing the "ping" hits returns an echo.
If you have a 6ft "hit" on the bottom & you go over a 7ft hole you
will
get
an echo from the bottom of the hole.
If you go over a 4ft hole you won't see it.
That's my understanding anyway.
BruceM