Which Fishfinder for a new Outback??

Just got a new Outback and looking to outfit it with a fishfinder. Any pros/cons on what to get? I've got a Garmin 60s GPS already so I don't need a combo unit. Also does the hobie fishfinder installation kit/batteries perform well all day or is there a better route to take? Thanks for any suggestions...

What kind of water and how deep?

I use a Piranamax tri-beam; but I might have gotten an Eagle Cuda or Lawrance for the ocean.

For example: For narrow rivers and some lakes you might want side-imaging, but in beyond the breakers, Ocean fishing you might want more depth. etc.
I'm near 7 lakes, some you can swim across and they'r 45 feet deep, others are 23,000 acres abd over 100 feet deep and a half-day's trip to cross.

I'll be fishing both fresh and salt water.........deep and shallow.....so I'll need a general good for everthing unit

I am using the Lowrance x50ds I got from my Hobie dealer and the mounting foam transducer pad 72021011 (about $3) and Marine Goop (about $7) mounting it just aft of the sail mast well in my Revolution. I am usually in the ocean where it can get pretty rough at times and have been very pleased with the performance. I did not use the Hobie kit though but purchased a 7ah sealed battery which I recharge with a solar panel (could be easily charged with a small trickle charger). I recharge weekly whether I use it daily or just once and never ran it down. I already had the solar panel ( 5watt) so this was by far the least expensive option for me and very easy also. I just use a velcro strap from Home Depot to hold the battery to the mast well and use a little Superlube (a Teflon lube, could use substitute) on the terminals to eliminate corrosion. The main unit is mounted on a RAM 5 spot mount along with my GPS, a rodholder and marine VHF or multi band ham radio (may eventually add an mount so I can mount both since I have another hole in the 5 spot left).

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Fishing, freediving and SCUBA diving off my Revolution when not just pedaling or sailing

I have an Eagle Cuda 350 map - mounted using a foam transducer puck gooped just fore of the mast insert. I route the cabling up under the foreward hatch, and have the FF unit mounted on a RAM mount with the expanding insert that fits in the mast hole. Battery is a 10 cell AA setup in a watertight box.

I've used it on three beach launches from Pacific City, Oregon, so far no problems that weren't my fault.