Thanks for all the feedback!
If it has only been seasoning for a month or so I would dare to guess it is not ready yet. You could rough it out to near bow dimensions and let it season some more by weighing it once per week until it stops loosing weight then you would be ready to finish it. Roughing it out will allow it to dry quicker.
Grady
My plan is to rough it to bow shape to speed up the seasoning process, I won't start bending it for a while yet.
Once it stops losing weight leave it on a radiator for a few days, and put it back on the radiator every time you leave the tillering for a day or two. Ash needs to be DRY as heck. Like properly dry.
Leave it as long as you possibly can to minimise stress across the limbs cos it likes to chrysal. 72" is fine if you're experienced with ash, but leaving it over 80" gives you a lot of breathing room and if you want you can pike it once the tiller is good. Depending on how crowned the stave is, either trap it or leave it crowned, because ash is stronger in tension than compression.
You could heat the kink up and straighten it, rather than trying to work around it. If you've not made a successful self bow yet, trying to negotiate a big s bend like that might be tricky.
It looks like a really nice stave, and you'll probably be absolutely fine but ash is fussy and suits certain designs better than others - wide flatbows for instance. If you want a long thin bend in the handle bow you have to fight it a bit and be very careful to avoid hinges before it's too late and they start to chrysal on you!
Ok I'll look to leave it as long as possible, if I go for the kink being the handle I should be able to get it long enough. Will heat treating the belly help? I'm definitely going to go with a flat bow design, I'm just wondering if the stave is thick enough to allow the handle to be stiff, I guess I'll just have to see how it bends.
Yes! You have exactly the right idea! 
That kink is the handle and it can even give you an almost centre shot. Keep the grip about 4-5 long max, leave it full thickness, but narrow it once the bow is almost tillered up to full draw, that way you can line the grip up perfectly with the string line .
Hopefully you can keep the back as the underbark surface and just work the belly. keep plenty of width to minimise the stress on the belly and avoid chrysals. (If the draw weight is too high you may need to de-crown the back, but hopefully not)
Go for this sort of style, but a bit longer for safety, you can always shorten it as it progresses.
http://bowyersdiary.blogspot.co.uk/2012/10/bark-on-hazel-finished-pics.html
I'm working on a similar style Yew primitive from a half a log similar size to yours at the moment, so keep an eye on my blog!
Del
(PS. That bow is now with JW Halverson in the US )
That sounds like a good trick, I'll leave the handle area alone for now then. If I de crown the back would I then have to back the bow to stop splinters rising? It does seem very rounded. That's a nice looking bit of yew, I need to make a shave horse like yours soon, that will definitely speed up the process.
Now is that 34" draw on a trad bow or a compound?
It is also heavily crowned. With your draw I'd go 74". Jawge
I've been drawing 32 inches on a board bow I've made, It's the first bow I've ever shot so I don't know if what I'm doing is right but it feel right!
