Computer Breathes New Life Into Scuba

Computers like those in new car engines will help Navy divers swim deeper and stay down longer without telltale bubbles.

Experimental diving gear incorporating a microprocessor is under development at the Naval Coastal Systems Center and should be ready for use by early 1993, said Steve Gorin, project manager for what is dubbed the EX-19.

A diver using ordinary gear can stay down 100 feet for about half an hour. “With this system . . . we can get in excess of six hours at in excess of 300 feet,” said Tony Ramey, head of the center’s diving systems branch.

Just how much in excess the Navy won’t say.

Workers at the center have been told not to disclose specific uses for the EX-19, although they could say it will be the first equipment used by all three types of Navy divers: fleet, explosive ordnance disposal and special warfare.

With regular scuba gear, known as an open system, a diver breathes air from a tank and exhales it into the water, creating the bubbles. Most of the air is wasted as the body consumes only a small portion of the oxygen in each breath.

The deeper a diver goes, the more air is wasted and the harder it is to breathe with an open system because air becomes denser. The diver has to breathe more air to get the same amount of oxygen and suck harder to get the dense air.

The EX-19 is a closed system that recycles air instead of letting it escape into the water, Gorin said. It uses two tanks, one with pure oxygen and the other with ordinary air or with a helium and oxygen mixture for depths greater than 150 feet.

A scrubber removes carbon dioxide from the used air and additional oxygen is injected as needed before it is breathed again through oversize hoses. The diver breathes as he normally would on the surface, Gorin said.

The Navy already uses re-breathers and at least one is available commercially, but the EX-19 advances the concept by using the microprocessor to control the recycling operation and handle other data. The diver wears a liquid crystal display unit on one wrist to read depth and tank pressure.

If something goes wrong, “idiot lights” like those on the dashboard of a car flash inside the face mask and an alarm, attached behind an ear, goes off.

Members of the development team are civilians but many, including Bill Gavin--lead mechanical engineer and a record-setting cave diver--and Gorin, have had Navy dive training that lets them participate in testing.

“It’s really strange to get into it because it makes no noise,” Gorin said.

Gavin, also a frequent user of open system gear, said he had developed habits he didn’t know he had until he tried out the EX-19. “When you get into a rig like this you have to almost re-teach yourself. Your ingrained training says you should breathe a certain way . . . and you don’t have to do that.”

Scuba divers can fill their lungs, increasing their buoyancy, to stop a descent or hover, or can exhale to sink, but those tricks don’t work with a closed system. “When you inhale you are simply transferring volume out of this rig and into your lungs, and your net buoyancy doesn’t change,” Gavin said.

Open-system bubbles can scare fish away, but they’re less frightened of the re-breather, Gavin said. For that reason and its other advantages, re-breathers are used by some research scientists, but their civilian application is limited by cost. A commercial unit goes for more than $20,000, and Gorin estimated the production version of the EX-19 will cost about $30,000.