Boat Anchor basic

How do you keep a floating object anchored? One way is to find a really heavy rock, tie a strong rope to it, and throw it overboard. But what happens when you want to leave that spot and go someplace else? Hauling that enormous rock on board may be impossible. You can just cut the rope attached to the rock, but then what would you do if you want to anchor the next night (plus you'd be littering)?

fishing knife cheapest gps gps rental