Love the film. Only one puzzle: Is Darby drunk when he dies?

I dislike movies that have too many cryptic plot points and too many unknown explanations for why characters do stupid stuff. This movie, however, explained every nuance to my satisfaction except for one.

When Darby shows up at the Hall family home late at night, apparently hoping to become intimate with Beau, is Darby drunk?

We know that during the car accident, the aftermath of which we see in flashback, Beau was drunk. Most likely, Darby gave him alcohol illegally. Beau is underage. Darby is an adult who likes to drink.

If Darby is drunk on the dock next to the Hall family home, that would make his accidental death very convincing. He impales himself on an anchor while Beau isn't looking. Beau isn't looking because Darby has become mean and violent and is chasing Beau.

The editor of this movie cuts away very quickly from the moment in which Darby impales himself. I had to rewind and review the fleeting image. The editor and director give you much more time the next morning to follow Margaret as she examines the dead body, the broken wood and the metal anchor, and her facial expression indicates she is deducing what happened.

For the remainder of the movie, Margaret never speaks the truth about Darby's death based on her being the only person who saw the dead body before she staged the scenario of drowning.

Therefore, I wondered how a physically fit young man could chase someone and then, while standing or walking, how he could impale his torso on a sharp metal object. I wondered that for a few minutes, then I decided, "Being drunk is a sufficient explanation for me." Any thoughts on the presence of alcohol? Thanking people in advance