First available in ScubaPro’s catalog in 1966, the ScubaPro Automatic Decompression Meter was a break through in diving technology and a forerunner to the modern dive computer. The meter attempted to calculate nitrogen absorption based on dive time and depth. This was done mechanically instead of electronically, and without the benefit of any actual computing. The Automatic Decompression Meter was introduced just a year after ScubaPro’s most successful product – the ScubaPro Jet Fins –  which still remain popular today.


According to the included manual, “The mechanism is a pressure-sensitive sealed bourdon tube in a sealed chamber. The only passageway into and out of the sealed chamber is through a porous ceramic element. The element precisely controls the flow of gas into and out of the chamber. The gas is contained in a collapsible plastic bag which is protected by the stainless steel case. An ambient pressure entry port and the strap slots allow for transmission of pressure to the collapsable bag.”

“On the surface, before the initial dive, both the sealed chamber and the collapsible bag are equalized to ambient pressure. As the diver descends, a pressure differential is created between the two gas volumes. This differential forces the gas through the flow-controlling porous ceramic element into the sealed chamber. As the pressure builds up within the sealed chamber, the Bourdon tube response causes the indicating needle to move in a clockwise direction. This movement simulates the nitrogen absorption by the diver’s tissues. Upon ascending, the process is reversed.”

According to one report done by the Scripps Institution of Oceanography, more than 50,000 units were sold, and the meter “has generally been consisted satisfactory” in terms of safety, but adds “this has recently been questioned”.

Because of their popularity, original ScubaPro Decompression Meters are still available occasionally on eBay and other online sources.