Topic: tried out my new 798 ci hd si unit today

[sdinkler1]

Tried my new 798 out today and love it so far   I do have one question, im having a little be of trouble actually seeing the fish on the side imaging view.  I know they show up as white specs as I have a DI unit on the bow, im sure I went by some fish somewhere today just didnt really see anything that  I know for sure was fish.  here is a screen shot that I took today does the image look close to what it should be as far as clairty etc.?  thanks in advance

[C. Corner]

Looks good, wish I could figure out why mine won't work.

[sdinkler1]

I seen the pic of your installation looks like it should work to me.  I purchased a 570 di unit last spring and had an issue with it and bass pro shops replaced the unit for me with no problems.  if you purchase yours recently you may be able to exchange it with them, if not I wouldnt hesitate to send the unit to humminbird they are pretty good about fixing the units and getting it back quickly.

[sonar2000]

SDI, your SI looks pretty normal. seeing a fish on si is not quite the same as a 2d. These are two different elements in the transducer.
Bait balls show up pretty good and occassionally you will get good returns of fish on or near the bottom.

Unless you know for sure there were fish in the scan area then it may be that on that day they just didnot want to be in your beam..

Keep playing with it as the display does look pretty good..
Set your screen speed to the boat speed and then play with sensitivity....

Chuck

[rnvinc]

I keep the "SI Enhance" window up on my screen anytime I am viewing SI...

This gives the abilitiy to change "SI Sensitivity" setting without (opaquing out) any other split view that I have up at the time...

I use the SI Sensitivity setting as a "brightness" control for my SI image (as different water conditions/bottom compositions will make the image brighter/darker..)

SI Sensitivity up will brighten the image...
SI Sensitivity down will darken the image...

I frequently change this SI Sensitivity setting as my SI image changes in brightness...

Rickie

[sdinkler1]

I will have to try the Si Enhance feature I think that will help a good bit, there was several times the deeper side was so dark that I couldnt really tell was on the screen.  thanks for the tip

[rnvinc]

Also in the "SI Enhance" window is access to the "Contrast" setting, normally at 10.... And the "Sharpness" setting, normally off

Once I get the brightness I want (at any given time) by adjusting the "SI Sensitivity".... I can turn up the "Sharpness" setting to "Low", "Medium", or "High"... This will increase the "graininess" of the image... But it will also make the fish echos "pop" out on the screen...

Here is a screenshot of the "SI Enhance" window overlayed onto the SI image...(this was a mud bottom so I had to increase the "SI Sensitivity" to 19 to get the mud to reflect enough echo to give an acceptable image..)

Rickie

[Humminbird_Greg]

With the Si sonar you are almost always looking at a farther distance being displayed than you would with the Di or 2D sonar.  This will affect how fish and other things are shown on the display itself.  Consider the image at the beginning of the post: when in 27.3 feet of water the Di/2D unit would probably be using a 0 to 30 foot (or perhaps 40 foot) depth scale.  The 570 DI has 640 vertical pixels to use to display those 30 feet.  So 30 feet X 12 inches per foot = 360 inches.  360 / 640 = 0.6 inches per pixel.  The Si unit in this image is using a 0 to 100 foot Si Range scale to display the area.  So 100 feet X 2 (each side is showing 100 feet) = 200 feet X 12 inches = 2,400 inches / 640 pixels 3.75 inches per pixel.  Any fish that is shown with say ten pixels on the Di/2D sonar would only be shown with ten pixels would only be displayed with 2 pixels on the Si view.

Just some rough numbers but you get the idea here.

[sonar2000]

We have the same issue in SAR with SI finding or displaying the target if it is not close to the boat. The farther out and the deeper it is reduces the si display to dots...
It is just the way the HB unit works and is why some of the guys have built tow fish to get deep clarity...
Does not help with side to side distance...

Chuck