Any tips for shallow water mapping?

I tried mapping some sections of the river last week. Autochart seems to work okay for the deeper sections, but the shallow sections get screwed up (3 ft or less). Some sections that I know are 3 ft, show up as 20 ft deep or more. Is there a setting on my 1198 that I can adjust (or a different beam to use) to get more accuracy? Or is there a way to manually edit an Autochart map after it is generated to correct for errors.

I'm just looking for a way to map out where the deep holes start and end in a river.

Thanks in advance!

Was your 1198 tracking the bottom correctly at these locations or did it start showing 20+ feet deep also?

I figured out a solution here. Basically, there are random errors in the Tracks file when you get too shallow (3ft) or less. So you can manually go into the track (right click a track and select "Trace Route") and edit and delete any erroneous readings.

Thanks for the info.

Watch the sonar data, especially if using Switchfire Max Mode. I would recommend Switchfire Clear in shallow water...sometimes you get very strong returns and wil lget double or triple echos and the Sonar Depth Number will read the multiple return.

I believe increasing your surface clutter in the menu will help with not getting the false reading. I had some 1100ft holes in 3 foot of water. it does make for a cool 3D image.