Learn Turkish: Yaralı olduğu için suda daha fazla çırpınamazdı. - Because he was injured, he couldn't have struggled in the water any more.

It is built on the verb çırpın- (to thrash/struggle). First, the inability marker -a is added. Then comes the negative aorist -maz, and finally the past tense -dı (he/she/it). The combination -amazdı (negative aorist past of ability) expresses a counterfactual past inability: 'he wouldn't have been able to' or 'he couldn't have' done it, even if he tried.

Why do we use olduğu için here instead of just oldu için to mean 'because he was'?

In Turkish, için (for/because) needs a noun or a nominalized verb to connect to a full action. We use the factive participle -dık plus a possessive ending to turn the verb into a noun phrase. So, ol- (to be) + -duk + -u (his) literally means 'his being'. Yaralı olduğu için translates exactly as 'because of his being injured'.

Is çırpınmak the standard word for 'struggle' in Turkish?

Not for all kinds of struggles. Çırpınmak specifically means to thrash about frantically, flap, or flutter. It is the perfect physical word for someone panicking in water or a bird trapped in a net. For struggling with a difficult task, an emotional issue, or a life situation, you would use zorlanmak or mücadele etmek instead.

How does daha fazla translate to 'any more' in this sentence?