Boulder Bags derive their name from gold dredgers and nugget hunters who use them for lifting boulders in the shallow rivers of California's mother- lode country. They are designed to get a maximum amount of lift from a single lift-point in a minimum depth of water. For example, the 2000 pound Boulder Bag gets its total lift in less than 3 feet of water, whereas the 2000 pound Open Bottom Bag requires almost 8 feet of water. These bags are very durable and have been used as air jacks capable of
more exerting several thousand pound of force over a large area. less
