I have the H2Oc hand held and use it all the time. But you will have to by a navionics chip or the lowrance one to get the depth contour maps of the lakes. That's another $100 or better. For and inexpensive FF the Fishmark 320 is a great machine as far as I am concerned. I've got one on two of my boats. I opted for the separate units as I can take the GPS on either boat or use it while hunting or hiking. If it's just for boating then maybe you would want a combo unit. It would be no bigger than the 320 FF unit. probably the cost would be about the same in the end for a colorunit if you look aroung on the net or check the sales. I believe there was an Eagle combo unit on sale at Cabelas or still is. Now don't forget the downriggers and the leadline rigs. OOps, now I'm running out of room and need a bigger boat.lol Good luck and happy fishing. Hope thi was of some help.