Topic: 150 ft limit of SI

[andrewg]

i read that the limit of 798 si is 150'.  but DI has 1500'
i am using the 798 si to record sonar files to SD card.
my question is

1. how will i know that the sonar will only be recording the DI image
not SI images?

2. are the DI & SI images all contained in the *.son files? or are they recorded in different files?

thanks.

[ITGEEK]

When you record, everything you can see on your views is recorded:
  2d, SI, DI, boat position.

[Humminbird_Greg]

The Di sonar in the 798 units is derived from the Si sonar beams and will have the same limit of 150 feet.  You may get more or less range than that depending on water conditions, bottom composition,…

[andrewg]

if DI & SI have same limit of 150' then what is the 1500' max depth in the specifications on humminbird website?

SONAR
DualBeam PLUS
200 kHz / 20° @ -10db
83 kHz / 60° @ -10db
Depth: 1500 ft.

I just want to know if I will have continuous recording of depth even if SI has reached its 150' limit.
I was testing my unit and funny thing is that my limit in depth is 49 meters or roughly 150'.

[Doc Stressor]

That's for 2D sonar at 83 kHz.

[ITGEEK]

You will always have a continuous depth to the bottom reading,
(recording or real-time), no matter what sonar screen you are on.
That depth is different than how far the SI beams can
shoot out to the side (150' max).

If your maximum depth is set to 150', then set it to AUTO,
or a number that is at least 10 feet greater than anywhere
you will be fishing.

[Bob B]

When you record you are recording the "raw" data......not just what you were viewing.

[andrewg]

thanks for the replies everyone!

[Lake Diver]

I was scanning shipwrecks today with my 798ci SI in 245ft of water using SI.  Could even see them on DI as well.  So I have no idea where they came up with the 150 or 100 foot ranges for the unit.

[Humminbird_Greg]

Water and bottom conditions will always affect how deep any type of sonar will work to.  150 feet deep for the Si sonar is about what most will see as a maximum.  This was derived at after testing at many water locations.

I would love to see screen snapshots of the 245 foot Si sonar readings.

[Lake Diver]

Here is the deep wreck scan with my 798 ci Si.  Shows both SI and DI images of wreck.

[sonar2000]

2d probably works best for larger targets at these deeper depths. DI next might be best and if the target is large such as yours then SI seems good.
Smaller targets such as those in SAR are best with towfish. And almost nil at 100 +...
Good pictures Lake Diver.
Chuck

[sonar2000]

I just thought of something else. With the ability to take out the water column on the display will help in the SI also...Something else to think about is to set the upper depth to 50 feet above maximum bottom depth.  This will reduce some of the screen upper display thru suppression. Something to try the next time out..
Chuck

[Lake Diver]

What is a good system to use to film the wreck at that depth - not an rov, what kinds of drop video systems would work to 250' and also not to costly?

[sonar2000]

LD....Drop cams would be very hard to control at that depth. Any current will move the camera and it is hard to make it do what you want because you are just dropping and not controlling anything but depth. Which is why we use the ROV's. Most drop cams of affordable cost are limited to 60 to 100 of cable.
Chuck

[newkid4si]

Would someone explain to me why the item in the 2D part of Lake Divers image shown at about 160' is not
seen in the DI or SI portion suspended.
Looking at the SI part, I see a shadow to the right of the target that I think
would be in the correct place if the target was suspended as shown in the 2D part,
and not sitting on the bottom.

         Mike

[sonar2000]

Mike, a very good question and one that I have seen before but just ignore as suspended "trash". One item I want to explore now is 2d with and without fish symbols on. The frequencies used and the portrayed view I seem to remember somewhat as different depending on the fish view setting. I may have to play more with this as spring gets here.  We use another brand for 2d display so that I can get the biggest screen display at the same time.  Which means we dont use HB 2d very much..
Chuck