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.
Did they come up with that idea while floating in sub-freezing water, after having just experienced multiple near-death scenarios, while afraid for their lives? The reality is that it’s easy to solve a problem in a lab, not so much under duress.
My favorite episodes are where they’re testing the prowess of some legendary athlete or fighter, and they, being two out of shape nerds, would try the feat, be unable to do it, and be like “MYTH BUSTED!”. I was glad to see when they called in an actual master of ninjitsu to test if a ninja can catch arrows, after they themselves were unable to even get close to catching one. That ninja actually did it too! Snatched some arrows right out of the air.
They have straps to tie them on you. You tie them together and hold them under the door. Or use any of the other crap floating in the ocean. Literally anything could be held in a shirt or pants. You can inflate your pants themselves by tying the legs together and blowing air into the waistband.
They try in the movie and it causes them both to be in the freezing water. It wasn’t about him being able to float, it was about them both not freezing to death.
Because you missed in the same episode during that part where David Cameron said that Leo’s character dying was what had to happen. That was the story. It is a pointless gotcha, based on the movie not spending the time to determine the exact amount of buoyancy of a ship wreck.