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 lb Boulder Bag gets its total lift in less than 3 feet of water, whereas the 2000 lb Open Bottom Bag required almost 8 feet of water. These bags are very durable and have been used as air jacks capable of exerting several thousand pounds of force over a large area. Please see the table below for sizes.