Main Page | See live article | Alphabetical index Wooden ships used to have their hulls waterproofed using tar. To facilitate this, a square ballast pond was built in the water with an entrance port on one side. A ship would enter the ballast pond and be tied to one wall. Then on the low tide, the ship would lean on one side to allow the tarring. On the next tide, the ship would be tied to the opposite wall to complete the job. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.