The Battleship was a construct created using Floating Spider silk. So, it was capable of levitating in the air automatically. And, if it wasn't chained down, it would float into the skies until the limit of its levitation was reached.
This was why all the web-worlds created by the Floating Spiders had a sturdy central rope that trailed from it and was attached to the ground. This was to prevent it from flying into the space, leading to the death of all the Floating Spiders that lived within.
The Floating Spider silk had incredible uses. Therefore, when Jyorta used it to create the Battleship, he obtained a mobile fortress that was capable of carrying the weight of him and his teammates without trouble.