I'm probably not the average Humminbird 997 SI owner but I am probably the happiest. I don't own a big fancy boat but rather have several "fishing" boats. The largest motor I have is a Chrysler 10hp. So - that having been said - I adapted mine to a portable unit and have had it in the water from the 12' deep Caster river to the 210' deep Bull Shoals lake, and mosy places in between. I've owned it for six months and have approx. 300 hours on it. I got the Navionics maps option and the temp/speed accessory. Seperately I purchased 2 SD cards, a 1 gig. and a 3 gig, and a USB port adapter so I could download all my info and screen shots to my computer. Total cost for the cards and adapter was less than $50. First, I took the motor off an old trolling motor and installed the transducer in it's place. I added the Temp/speed wheel 4" above the transducer, and the GPS puck to the top of it. This allows me to mount the unit on any boat that I choose to fish from. It became extremely adjustable in almost any situation. I've had it on a 14' canoe all the way up to a 50' houseboat. I bought a medium size plastic tool box that I mounted the head on, and store the head and accessories IN the box when not in use. Works great. I admit that it was/is a little intimidating at first (it comes with a 143 page instruction book) but I learned ONE THING AT A TIME. Learn one well, and go to the next, ect. Eventually I learned to use it in two modes at once (split screen) and now enjoy the boat ride to and from fishing spots as much as fishing. When on a body of water that the nav. charts cover, I can follow a contour line perfectly for miles, no matter how deep the contour line is. When in uncharted water I can still see exactly where I am and where I've been. The speed sensor is so sensitive that I can troll at any speed and maintain it in 1/10 mph incriments. Walleye at .4 to 1.3, stripers faster, ect. I've found so many "bait balls" and bait balls with fish hanging underneath that I am still amazed. Using the side scan, I can follow submerged roads and see old fields, house foundations, virtually everything on the bottom. I actually found the old road going past Jones school (Bull Shoals lake) and the school foundation. My mother went to school there back in the late 30's. I sorta had an idea where it was and found it in about 1/2 an hour. I could go on and on for a couple hours on the 997's neat things, but the bottom line is "If you can afford one of them - DO IT!". The 997 brought a whole new dimension into fishing for me and wish that I had gotten one sooner. I'm retired and fish as often as you change you're socks, (except MrT, I think he changes them a couple times a day) and this is the greatest thing I have come across so far. I'm in town and out a whole lot but I will answer any questions any of you may have when at home EXCEPT "can you identify a catfish" - NO, but you can identify "A" fish and whether it is large or small and exactly "where and at what depth" and whether it is a single or a school. Experience and habitat knowledge are the only way to do that. This thing does everything else.