How I draw feathers (and something else for fun)

For fun, the magnets on the side of my fridge, they're not on full display as normally the kitchen door is open against the side of the fridge. The magnetic calender with one of Ferret's nudes arrived in today's post.
I start by outlining the area I must not go outside. In this case a 6" square. Then I draw the spine, followed by a rough guideline for where I want the lobes of the feathers to end.

Then I start by drawing the first lobe at the bottom on the right hand side (this one is the most difficult to make elegant but don't worry you can redraw it later if it really ends up badly) Each lobe starts from the spine. If I were left handed, I'd start on the other side of the spine.
When I get to the end, I do a final lobe but this time I start this final one from near the top of the preceding one. Instead of taking it back to the spine, I take it nearly to the spine then continue down nearly parallel to the first line. This gives you a nice double spine. Then starting at the bottom again, I draw the first lobe. I draw the next and all the following ones, not from the spine out but from near the tip of the lobe before it.
You can see I've gone outside my rough outline near the tip of the feather. This is OK, it's only a guide and when you reach somewhere where the rough line looks wrong, then go with what 'feels' right.