Take a look at The THT, Do a search for side scan
LSS-1 Depth capabilities in salt water - The Hull Truth - Boating and Fishing Forum
Lots of good info.
I have a HDS-10 with side scan. They have there limits, The best I've done with side scan is 60' to 80' of water on a calm day. Down scan I've had good results down to 120'. I've posted some screen shots on THT