Equitable compensation on a totaled Sea Doo?

Okay, so I made a lake trip with relatives and one if their friends. In the process, I managed to run dirt and sticks through the intake on the friend’s Sea Doo (a 90s model). It gummed up the throttle, but we were able to flush it out on the beach and restore the throttle to 85–90% capacity.

Thinking we were in the clear, the friend allowed me back out for a while, and I ran it normally, including at full throttle. When I got back, he took it out and ran it normally at full throttle, plus did a bunch of hairpin turns, etc. (ran it harder than I did, let’s say). In the midst of his run, the engine died, and that was the last use on the trip.

The diagnosis was a torched engine, essentially. Probably a cracked cylinder or whatever and the repair bill would have been $4k, so he just turned over the title to the repair shop and said goodbye. Also, he did not carry insurance on the jet ski.

This will be settled civilly and as friends, but I’d like to get a sense from the collective on what’s equitable compensation.