“But someone considered an expert for his era.”
No he wasn’t at the time. He wasn’t even eligible for command of a ship in the Navy at the time. His political dealings with Seward was the only reason Porter got command of a ship.
I think I am not accurately communicating my point. When Porter wrote that book he was an Admiral. He didn't write it when he was a lieutenant.
According to Admiral Porter, those ships would have been quickly sunk.