Thanks for your comments. I used a german glue called "Bindan Propellerleim". Its waterproofed and the name says, that props of aeroplanes are glued with it.
I read in Germany that some bowyers use it. Another good german glue is "Ponal blau". I have used this too, but the propglue seemed to be a little stronger by name. So I used it. I think that this bow needs a strong glue, because of its highly stressed construction.