If the Trojan construct were a boat, that would make no sense at all. It was believed to be empty. So, the residents and military would not examine below decks to see if a boat were empty?
A boat would have to be wheeled (which again makes no sense for a city next to the sea) or floated. Meaning there would have to be a water channel into the city, which would be and extremely vulnerable point and the city would have fallen to siege MUCH sooner than it did.