Last time I checked, Noah's Ark was not a submarine barge. And it is my understanding that people have build replicas of the ark and these boats float. That can't be said for Joseph Smith's Jaredite vessels.
Here’s a link to the atheist page on which his analysis is listed ... he rips into Jesus and the Bible pretty hard as well.
Packham came out of Mormonism and became an atheist. It is my understanding that, unfortunately, the same is true for the majority of those who leave the cult.
Last time I checked (admittedly a few years ago), his site contained arguments that were debunked decades ago. Christian apologists such as Lee Strobel and Josh McDowell have written extensively on the topic and are worth checking into before you or anyone else make a final decision.
Check Noah’s Ark again. Look at the specs. The “Arks” that have been built aren’t to the specifications laid out by God.