You just described an average day on Mythbusters.

They don’t put the life vests under the door in the movie, which is the key detail tested by the Mythbusters.

Idk why you’re being downvoted. They did, and you’re right. A door of that size made with accurate wood could hold two adult men out of the water when they removed their life vests and put them under the door.

If Jack and Rose had done the same, they would have increased the chance of survival for both of them by both being out of the water and having double the body heat to warm each other.

“Lolz, what union?” - My Boss

Simps. /s