The boom stretches from the shore out across the surface of the water and floats on the water. As the tide goes out and the water level drops this boom sits on the exposed bottom. When the tide comes in the boom once again floats. Thus oil on the water cannot get around the shoreline end of this boom as the water surges in and out. Water is the common type of ballast used in this boom.
Examples are curtain boom and fence boom.
In general, curtain boom is used in rougher offshore areas and fence boom is used in areas closer to the shore or inland. These oil booms serve the standard purposes of containing, collecting, or deflecting spilled oil. Used, as the name implies to contain oil while it is set on fire and burned. Thus fire boom must have features that permit it to endure under extreme temperatures for a period long enough to serve it's purpose. This boom is constructed of fire resistant materials such as ceramic textiles and stainless steel mesh.