I agree, but i think cameron wanted to make it dramatic, and to show off the special effects. I think the real ship didn't cause waves like that, like you said if the ship had caused huge waves, people would have said something. I know the ship had like 66,000 tons water displacement, but the ship had broken up by then and the biggest section(bow) was gone, which left the stern. I have no idea the water displacement for that, but it would be far less than the whole ship. He may have been usinf 66,000 tons when he calculated the wave action caused by the stern. I still find it hard to watch the sinking scene in any movie...just the thought off all those people...