Wooden ships back during slave trade were crowded with bodies and were still heavy with ballast because flesh and bone are relatively light.
No case for a real boat, an Ark, can be argued on any grounds. It is a symbolic story that Jesus referred to as being the same as His experience. You will note that there were no global floods in Jesus day.
Don't believe me believe Jesus. Nature could not rebound from such a flood for hundreds of thousands of years and the natural order that returned would be nothing like it once was.
It just didn't happen as a literal event as described.
