This is my first post here after absorbing as much info from you guys as I can. This is a great site!
So, I was out on the lake the other day doing nothing but trying to get familiar with my new 520C unit, with a transom mount. This is my first fishfinder/gps unit. I was marking some spots I was watching on my sonar, throwing a buoy over to mark it, and practicing getting back to it. I could never get back to the exact spot. The "arrival alarm" would go off about a 100 yards or so from the buoy I had thrown to mark the spot. I know these units are more accurate than that. How close should this unit get you to a marked waypoint? Am I doing something wrong?
Thanks in advance for any help.

sent you a pm

Good question texxasguy. I wish we could get some answers. I like my Lowrance, but there's a lot I don't know about it.

You will need to use a few additional features of the unit to get you back on the waypoint - Zoom, EPE (position error), and Steer arrow. EPE will tell you the accuracy using factors such as satelite signal strength, number of satelites in view, etc... For example, if you have an EPE of 30' and the unit says you are on top of the waypoint, you could be 30' off from the waypoint. The steer arrow will point you in the direction of the waypoint and show you how far you are from the waypoint.

While on the map page overlay EPE and the steer arrow using these directions:

Menu --> Overlay Data --> Enter
GPS Data --> Position Error
Navigation --> Steer Arrow

Exit back to the map page. Zoom in is far as possible and use the steer arrow to get you back to the waypoint.

Thanks Pivo, I'll give that a try. I appreciate the help!