Did you put the limbs in the water while the water was still cold? lf you waited for the water to boil first, and then put the limbs in the boiling water the limbs can crack. Bring both wood and water up to boil at the same time. And dont give up on making recurves and make flatbows only, this stuff happens. And just how deep are the cracks on the back anyway? lf they're not to deep you can chase it down another ring or so...you got alot of wood to work with from what l've seen.