>>2443371My prediction is whomever is crossing the river by pulling himself along the rope in an inner tube or whatever, is going to die.
This will happen because you al have no experience with river rescue and your only instruction in the matter is this infographic you've posted. The rope will sag badly, it will be far more difficult to make his way along it than anticipated, and tying off the stuck boat will be about impossible without getting washed down river.
Depending on the flow and features downstream he will either break both his legs and both arms before his head is bashed apart, meaning he will die in excruciating pain, or his head will go first and he will die only in terror. In both cases the meat will be ruined due to his endocrine response before death.
So you have to decide whether going after the stuck boat is "worth it". You aren't getting it back regardless. All you'll get is a dead friend. But you will have. story to post here as follow up.