It is called a Pirate Ship because it resembles a ship. It is not intended to function as an actual ship at sea or lake. The picture on the front cover is the fort that was designed for this plan.
Some modifications were made to simplify this plan for the novice. The original was designed to be a solitary 3x20x7 fort. Other parts were added, such as an optional mast that could reach eight feet or higher. This is obviously optional. It will be easy to add these portions later if you want, rather than build the entire thing at once.
These instructions are a guide to build a three foot wide and 17 feet plus long fort that is roughly seven feet tall to the top of the railings. It has a step unit leading onto the port side. The deck is four feet from the ground and the Aft deck is five feet from the ground. The underground area is four feet from ground.
Cost: The price for the materials to build this project would be dependent upon what material that you purchase. Some lumber is more expensive than others. However, the original structure was designed with standard pine so the general cost would be around $1500, that would include hardware.
Buy on paperback $9.99: http://www.amazon.com/Pirate-Ship-Fort-Guidebook-8/dp/1506132375