I take my 798 in the house to do that stuff.You don't have to have TD attached.It does like to have the gps working for some reason.Do the transferring with sd card.Go to nav menu and should see all new waypoints in the waypoint section.
Bob
Sorry Bob you've missed the point, I already do that (from above):
I have HumminbirdPC etc but my only problem is that I've got hundreds of waypoints, now that I've re-named them the only way to check the thumbnail image is either while the unit is on, or if I've been lucky enough to store an image with the coordinates showing (note this is obviously slow!).
So I need power to the unit to check the waypoints that don't have co-ords on them. So I'll have to look on the chartplotter screen, as in HumminbirdPC you can't check the waypoint snapshots, except in the snapshot folder but you need the co-ords to be saved on the screen as mentioned in my post, and as I've got 348 snapshots now that's a lot to look through.