Why does Quint blow the Orca's engine in Jaws?

By the time that happens, Quint has become totally obsessed with defeating the shark. His behaviour is initially pretty erratic and he becomes more obsessed over time. Remember he smashed the CB radio, thus preventing any chance of calling for help.

There is almost certainly an element of Captain Ahab from Moby Dick in the character of Quint, a complete fanaticism to kill the shark that prevents otherwise lucid thoughts of survival. In another parallel with Moby Dick and (specifically) Ahab, Quint had previously been traumatised in the USS Indianapolis incident.

From the beginning Quint did things his way, which, on the face of it, were not the most sensible of options. For example, Hooper has a well equipped boat in better condition (and faster) than the Orca - why not use that ?

Quote from Wikipedia:

Herman Melville's Moby-Dick is the most notable artistic antecedent to Jaws. The character of Quint strongly resembles Captain Ahab, the obsessed captain of the Pequod who devotes his life to hunting a sperm whale. Quint's monologue reveals a similar obsession with sharks; even his boat, the Orca, is named after the only natural enemy of the white shark. In the novel and original screenplay, Quint dies after being dragged under the ocean by a harpoon tied to his leg, similar to the death of Ahab in Melville's novel.[80] A direct reference to these similarities may be found in Spielberg's draft of the screenplay, which introduces Quint watching the film version of Moby-Dick; his continuous laughter prompts other audience members to get up and leave the theater

Source

I just watched the scene and looked online to see what people thought. As for the last reply, I don't think he took a gamble at all. He could see that he was blowing the engine, they zoomed in on the tach several times. He intentionally blew the engine, and he could have backed off as it was falling apart. Whether he wanted to die or wanted an 'end all battle' is up to you to decide as the movie doesn't give a definitive answer. I don't necessarily consider this the same as him destroying the radio though. He did that to keep others away from his battle. Blowing the engine cost him the battle, which is why it doesn't make rational sense.

I think Quint wanted to inflict as much pain as possible on the shark, and I believe he wanted to will the Orca to do what it could not do: move at full throttle while approaching land. Quint and Orca were one. He refused to admit that the shark had injured Orca. He wanted to totally defeat the shark, and would only accept full victory. He gambled, and he lost. He felt that Brody and Hooper were collateral that could be lost.

I think he's scared beyond reason in this scene. Survivors guilt is part of earlier actions, I believe, but in this scene he just wants to get back to land and away from the shark. It's like he knows its his destiny to die this way but is trying to outrun it. I think he shows real fear in this scene, and then once the engine blows, there is nothing for it to turn and face his fears.

Basically because Quint is being a hot shot.

In all seriousness I laughed for like a month over this scene. I even drew a comic about it and wrote in clip-lines from this movie although I really embellished them some where hooper kept making calculations of how far land was and how thick the engine's smoke kept getting.

Quint is so dumb here. It's like they've already won the ball game and all Quint needs to do is kneel down on the ball and that's it, but it's like he's going for another touchdown.

That's what makes it so funny. I mean I've never seen anyone act so dumb before in cinema history.