Shanahan Crag descent?

Hoping to scramble up this tomorrow with the kids.
Is a rap mandatory if descending to the west from the summit?
If so, any idea how long a rope is needed?

Short scramble off the back

Good beta Mark, thanks!
Although now that I look at some pictures, I'm pretty sure we climbed the SE ridge of the North crag!

I was gonna say: depends which rock you are actually on.  

Mark D.
You would be far from the last to scramble a rock other than the one which they intended.  That area is confusing/hard to see.
I've done 'the wrong rock' more than once up there and I have climbed pretty much everything in the book (below 5.12 anyway), so I supposedly know the area.
Difficult to get on the right rock without starting first on the upper South and working down and around.  

Tony, are you saying that a rap is needed for mortals from the top of the central shanonhan crag?

Brian Asbury wrote: Tony, are you saying that a rap is needed for mortals from the top of the central shanonhan crag?

None of those words seem to appear in anything I said.  Can you tell me how you derived that from a comment about trying to figure which rock is which?