Ascent rate indicator

Invention: Ascent rate indicator

Year	Description
1992	Invention patented by Mark Thurlow on June 28th, 1992. Abstract: A non-mechanical ascent rate indicator for use in saltwater scuba diving. A high density sphere attached by means of a ball chain tether to the gauge, or hose, of a scuba diver has a free rate of ascent of less than 60 feet/minute, the difference in this rate and that of the diver will be shown by the amount to free loop in the tether as it is observed on a horizontal plane even to the diver's eyes. A safe ascent rate will provide a loop of approximately 1 to 11/2 inch.
Source: selected by the editor from original sources.