Its pretty difficult as nothing can be proved, my guess is the most likley cause of failure is something fouled on the prop, I have direct knowledge of a gearbox pulled off of a 1000hp engine and P bracket pulled out of a steel hull from fouling, so the forces are huge. The coupling could possibly have been the weakest link.
Any insurance claim against a company or product needs proof that it or they were at fault, but it could be worth checking with your insurers, I was covered on damage caused by debris on my last boat.