A racking cane is not strictly nessecary for siphoning. However, a racking cane makes it easier to control how much trub is taken from the primary.
Personally, if you're going to buy a racking cane, spend a few dollars more and get an autosiphon. They are really a great way to go.
Jason 'Kornkob' Robinson
I wanna move to Theory. Everything works in Theory.