What is my desired use and what type of vessel will it be mounted on: the boat is an 18 foot aluminum with a 120 hp motor and a bow mount trolling motor. I want to be able to 'see' bottom structure in lakes where I can fish for trout or salmon (so maybe a max of 150 feet deep - for my use), and to find holes in much shallower bodies of water like rivers for walleye, pike and muskie. I would mostly be using it at a 'trolling' speed, up to 6-7 mph max. It would also come in handy if I am out cruising on a lake at faster speeds, so I am told certain models won't 'keep up'.
I don't feel the need for GPS or a huge screen like some newer models have. I think a reasonable budget for me is about $300 max.
I was shown a model at a local store that was supposed to meet the needs of the average angler with a similar boat and motor package. The unit was an Eagle - a model year old, (I think) 320 x 320 resolution with 1500 watts of power and a 3.5 x 5 or 4 x 6 screen, for about $235.00. It had some limited capability to show thermo-clines (temp variations at different depths), could display either fish symbols or arches, and had some alarms and programable features.
Does anyone have any comments or suggestions about different units?



Any help is greatly appreciated.
Mike