The original Titanic was about 883ft long and DWT 46,328t. Today, the largest in service ship, in length, is the containership Emma Maersk with 1302ft and DWT 156,907t. But the record is held by the tanker Seawise Giant with 1504ft and DWT 564,763t, unfortunately already scrapped.
Is probably better for you to try to discuss this subject with your professor and findout what he thinks. You can make any design as hard as you want, no matter how simple it might look, but whether you are going to satisfy the demands and requirements of your professor is another story.