@Setanta,
The answers to your questions can be found through the link I gave, as well as google of course.
One of the main differences between the largest ship ever built on record and the ark was at the ark did not have sails to add extra tension/twisting Which could sink the boat. All the ark had to do was float, not sail. It was built 6:1 ratio which is best for seaworthiness. You are comparing apples to oranges when you make such statements.
Ancient civilizations could build things we could not today like pyramids.
As for the life spans of people who lived before the flood, this is just the reflection of the different climate and conditions they lived in.
Take for example before the flood everything was bigger. There was giant insects, giant mammals, giant reptiles giant plant life, giant people....(Because of the different climate in conditions they lived in.)
For example, it is impossible in today’s climate for a bipedal reptile weighing in at several tons To exist, yet not be possible in the past.
Also, the mountains we observe today were just minor Hills if anything before the flood. There have been fossils of sea creatures found at the top of these mountains. There was and is more than enough water to submerge all the dryland on earth if it was more flat, Which it obviously was.
It definitely seems that all the oil fields, and fossils globally our best explained by a global flood.
It seems we did not evolve from Africa, but rather migrated from Africa, from where the ark landed.