So many easy ways to get back on the boat
I thought of these in the first few minutes. I'm sure you did too.
1. If you look at the bow/front of the boat, there's something sticking out that's lower than the sides, where they keep trying to get on. That coud've been grabbed much easier.
2. Making a rope out of the clothes was pretty obvious, and should've been tried sooner. No reason it couldn't have worked -- almost did the one time. (Why couldn't that wuss climb aboard with it?)
3. The life-jacket could've been used as the "hook" of the rope, to catch onto the wires better. The girl could've floated for awhile.
4. Anyone ever vault a child or friend into the air while in the water by cupping your hands and having them step into them, and then vaulting them over your shoulder? Could've easily done this and gotten someone up to the point where they could grab the wires.
5. Have one of the lighter girls climb on the inflatable dolphin. NOT one of the heaviest guys.
6. Finally -- people are naturallly bouyant. Two guys could've filled their lungs and held their breath while a girl stepped on their backs and reached the deck from there. (The deck is only about 4-5 feet over water level.)
This movie could only be credible if the deck was significantly higher than it actually was. Then, none of the above tricks may have worked. As it was, there's no reason most these couldn't have worked. Relatively easily.