I’m trying to understand the following sentence (the bit in bold is what I’m struggling with):
Schon bei diesem ersten Anprall wären weniger erfahrene und tapfere Seeleute als die der „Argo“ zweifellos zur einen Hälfte über Bord gespült worden und zur anderen in Ohnmacht gefallen.
I think this means (more or less):
Already by this first impact half of a crew that was less experienced and brave than the crew of the ‘Argo’ would undoubtedly have been washed overboard, and the others have fainted.
I don’t really understand the function of the ‘zur’ though.