I would stay with the more simple units, like one of the 125-150 dollar units at Wal-Mart. Mine is a portable battery operated Lowrance unit that works very well in all my boating applications. It has a map and plotting feature that I never use. The basic information, ie, range and bearing to a waypoint, are all I seem to ever use. Knowing your true groundspeed is also cool and I think all the basic units do that. (On that subject, the previous owner of my jet skiis swore that they would do 60 MPH but my GPS quickly showed that they would max out at 45 MPH. But a true 45 MPH seems like you are flying over water!!!)

Knowing your altitude is also quite handy for hiking and the basic units give you that too. I also like the portable units because they are isolated from the boat's DC power and are not dependant on it. Most also have plug in 12 volt DC adapters in case the batts go dead, which of course will happen sooner or later.

MB