Topic: help please

[Hutchy]

Hello  all I am a newbie. I have got  a 798ci si hd. I fish estuary and close inshore ocean. My side scanning doesn't seem to have the detail it should. Cruising through the three bridge crossings and I could detect pylons. Any suggestions. Thanks  for your help.

[Humminbird_Greg]

Try posting a Screen Snapshot of what your unit is showing you.  Most can than make setting suggestions based on what they see.  It would also help to post you Si-sonar menu settings as well when you post the pictures.

[Hutchy]

Thanks Greg for the suggestion, do I take screens shots with my camera phones. If its not seeing bridge pylons, its gotta be in the settings somewhere, yeah?
Rgds
Hutchy

[rnvinc]

Vertical structures such as bridge pilings are a challenge with SI technology...

The first thing to understand is that the SI sonar beam is very thin front to back..(less than 1 inch at the xducer)...

Then consider the speed at which you pass by the vertical structure...

Taking those 2 points to mind...it is very likely that there are actually very few sound wave "pings" that come into contact with the vertical structure to be reflected back to the xducer...

Just for explaination sake let's say you are SI scanning by a bridge piling that is 3ft wide...
Let's say the boat is travelling by the piling at 3mph...

This scenario only allows very few sound wave "pings" to reflect off the piling...

Then, when the unit plots those very few "successful pings" onto the SI image screen ...it's just not going to show very wide on the SI image...

Even if it amounts to 10-20 successful reflected "pings"... That's not going to plot very wide on the SI image

There are 2 ways to overcome this scenario...

1. Slow the boat down to allow more "pings" to hit the piling...
2. Speed the chart up to stretch the few successful pings out across the SI image...

Rickie

[Humminbird_Greg]

Take the Screen Snapshots with the Screen Snapshot feature in your 798ci HD Si unit Hutchy.  Look for the Accessory menu tab in the main menu system of your unit.  Open this up and look for the Screen Snapshot menu and set it to “On”.  Install an SD or SDHC memory card into your 798ci HD Si unit.  Each time you want to save an image of what you are seeing on the display of your 798ci HD Si unit, just use the MARK button.  This will make a Waypoint at that location and also save the image to the memory card.  These are *.png files and can be posted on most web sites and viewed by the standard picture viewing programs on most computers.

[Hutchy]

Thanks for the information Rickie and Greg. Very generous of you to give your time to sharing some knowledge.
I will put you advice to work
Rgds
Hutchy