1^st Class Navy Diver
UDT: Teams 5, 11, and 13

I recently spent an afternoon with Harold Nething. We talked about his Navy career spanning World War II through the early 1960s. He is such a wealth of information and has so many interesting stories to tell, I could have easily filled a book. However, for purposes of time and space we’ll concern ourselves here with the pure oxygen rebreather he designed and built in the mid-1950s.

In 1943, at the age of eighteen, Harold volunteered for the Navy. After basic training he spent two years in the North Atlantic and the Mediterranean aboard the destroyer Livermore (DD-429). When the War ended in 1945 Harold went to Deep-Sea Diving School at the Naval Gun Factory in Washington D.C. Upon graduation his first diving billet was on the Sperry, a large submarine tender out of San Diego. "They put me in charge of the diving locker right off the bat," Harold said. "This was a great assignment because I was able to do a lot of hands-on work with the diving gear, i.e. maintenance, repair and often some innovative modifications." Harold is really a self-taught engineer. He loves nothing better than improving on an old idea or sketching out some new design and then fabricating it. He’s proficient at lathe and mill operations as well as welding and brazing.

Harold’s diving assignments varied over the next few years. Then in 1953, while in Japan assigned to the Reclaimer out of Pearl Harbor, he saw a notice that volunteers were needed for UDT. Always looking for a challenge and ways to further his diving career he put in for the UDTs. His orders soon came through and Harold was off to Coronado for UDT training. "I thought I was a good swimmer until I joined UDT," Harold said. "Boy, did they make us swim." Actually he didn’t have too much trouble with the training. Harold was in great physical condition after eight years experience as a 1^st class Navy diver, even "Hell Week" wasn’t too bad. "I kept my eyes and ears open and my mouth shut," Harold said.

After graduation Harold was assigned to UDT Team 5. He was soon off to Camp McGill in Japan where he received aqua-lung training. "You’ll have no trouble with this diving gear," the training officer said. "Just breathe through the mouthpiece like normal and swim." He was right: after diving, the heavy MK 5, scuba gear was a cinch. Training continued and Harold furthered his diving skills learning under water navigation and locking in and out of submarines.

Harold returned to Coronado after a year in Japan and was once again assigned to the diving locker. This is where our rebreather story really begins. A new shipment of Pirelli rebreathers had just arrived from Milan, Italy and the Teams would have to be trained in this new piece of diving equipment. Because of Harold’s background as a 1^st class Navy Diver, he was selected to teach rebreather training at the amphibious base pool.

Rebreather training was started and because of Harold’s natural curiosity and desire to improve things, he immediately recognized that the Pirelli might have a design drawback. The Pirelli is a pure oxygen rebreather located on the diver’s chest. The scrubber canister is inside the breathing bag and the oxygen tanks are attached below the breathing bag. This arrangement makes the apparatus front heavy which tends to pull the divers head forward and down when he is on the surface. As often happened in training, the diver would pass out, usually from oxygen toxicity. Each diver has a different tolerance for oxygen under pressure. Because the Pirelli is mounted on the diver’s chest, when he rose to the surface he would be in the face down position. If a rescue diver didn’t get to him in a hurry the diver would drown. Because Harold was instructing, this situation was always on his mind. However, because of a busy schedule there wasn’t much he could do about this at the time.

Rebreather training continued and soon it was time for an ocean dive under more realistic conditions. The decision was made to combine a night dive with a sneak attack to check harbor defenses. "We went in by rubber boat, climbed up over the jetty and began our swim toward Ballast Point,": Harold said. "We’re on the North side of the jetty that runs out from North Island." Swimming toward Ballast Point the searchlight swept the surface of the water. As the bright beam of light approached the divers, they ducked beneath the surface to avoid detection. Harbor defenses were on full alert that night. They were warned of the drill but didn’t know if the approach would be from the land or sea. Finally it was time for the divers to submerge and make the final assault on the Point. Purging their rebreathers the swimmers dropped below the surface and swam on. "We submerged and that’s all I can remember," Harold says. "My swim buddy pulled me to the surface and upon the rocks." What happened? Well, that was the end of the dive for Harold that night. Thanks to his swim buddy he was revived and o.k. But what did happen? Was it equipment failure or oxygen toxicity? One thing was for sure, Harold knew how to use the rebreather. Hell, he was the instructor.

"Doug Fane was there that night, to observe the operation. He was the "Big Dog" in UDT at the time. He found out I had trouble with my Pirelli, and wanted to know what went wrong," Harold said. "He asked me to let him know what I found out."

"After some investigation it was discovered that in the breathing bag where the scrubbing canister attaches to the breathing hose, there’s a fitting that’s sweat soldered on…well, it had parted and failed. Later, after testing all the Pirellis, about 85% failed. The reason I passed out that night was that the canister and my breathing hose had parted and I was just breathing out of the bag itself. My CO2 wasn’t being scrubbed out. It was like having a bag over my head."

"That’s when I got the idea, we’ve got to have a better rebreather, because it’s an effort to breathe. Breathing through the scrubbing canister, you’re breathing against the sea pressure all the time; and if you make it difficult for a diver to breathe. There’s no slacking off period, you’re breathing hard 100% of the time."

"So I’m thinking to myself, ‘Why can’t we have a rebreather that uses a system like they have in "hard hat" with the shell-natron scrubbing canister and a oxygen-helium mixture?’ You could hook that up to a rebreather with a demand regulator and the scrubbing canister in the bag or next to the bag, either under it or over it. I made more drawings that I still have of that idea. I worked on it for awhile then it fizzled out. Then I got to working on it again and I eventually came up with the idea for a strictly oxygen rebreather, but not with shell-natron but with baralyme in the canister. What I wanted to do was put the canister right next to the breathing bag or under the breathing bag on the front of the diver and the oxygen bottle on the diver’s back. This would make a better balanced unit, so should the diver black out his head would be in the up position and out of the water when he was on the surface, solving some of the Pirelli problems. Final design resulted in the breathing bags high up on the chest, scrubbing canister under the bags, and the oxygen bottle on the diver’s back. I started scrounging parts where I could find them and began building it aboard ship. I got hold of an old OBA (oxygen breathing apparatus) and I split the breathing bag in two. In Yokosuka, the town near where my ship was berthed, I had the bags vulcanized. So now I had two bags, one for inhalation, one for exhalation. I made a scrubbing canister out of an old brass voice tube and I modified various valves and fittings to complete the rebreather. Filters were installed in the canister to keep the baralyme out of the breathing bags. Hoses were adapted from a double hose regulator. A demand regulator (U.S. Divers Aqua-Matic) was modified and installed on the inhalation bag. The modification allowed the regulator to operate in the demand mode or the manual mode."

"After completion the Diving Officer said, ‘Harold, bring your rebreather to the pool for testing.’ So we put five divers in the pool, this was in Yokosuka. They all thought it worked pretty well; it breathed easier than the Pirelli. The double breathing bag system seemed to work better than the single bag design, because you weren’t breathing through the scrubbing canister with each breath. You exhaled into one bag and inhaled from another. As you inhaled from one bag and emptied it, the sea pressure would assist and help push the exhaled gas through the canister to the other bag. As you breathed one bag would fill and one would empty; you could see them alternate inflating and deflating. Because the sea pressure would want to equalize the pressure in both bags, it helped more the gas through the scrubber. At the end of the breathing cycle, if you were a little short of oxygen in the inhaling bag you could hear the demand regulator deliver the volume needed by the diver. The hoses were located on the bags in such a manner that if you got any moisture in the system it would collect in the bottom of the breathing bags and not get into the scrubbing canister with the baralyme. Because if the baralyme gets wet you’ve got big trouble, a cocktail you don’t want to breathe. Everything worked out great, including the Healthways (Hope-Page) mouthpiece I modified to be able to shut off."

"Continued testing in the pool worked out fine. When I got back to the States, out of nowhere one day 1^st Lt. Wendy Weber called me into his office and said, ‘Harold, we’ve further checked out your rebreather and the Navy would like to patent it for you.’ – and I turned them down. Why I did that I don’t know. Now that I think back it’s the biggest mistake of my life. But at the time with the aqua-lung gaining popularity, who would want another oxygen rebreather on the market? In retrospect I was wrong because here 45 years later the Navy is still using rebreathers. Anyway, now it’s water under the bridge."

Recently Harold’s interest in diving has been revived; he found a group with similar interest, The California Classic Equipment Divers. These divers collect, restore and dive vintage gear: hard hat, scuba and rebreathers. Harold dusted off his old rebreather and brought it to one of the dive meets, where it stirred up a lot of enthusiasm. Just as the Navy was impressed with it years ago, so were the divers in the CCED. In fact, one of the members has incorporated some of Harold’s designs into his own custom built rebreather. It often seems that a good idea is timeless.

Late last year while the CCED was putting on a dive demonstration at the College of Oceaneering in Los Angeles Harbor, they dressed Harold out in Heavy Gear. Harold took his first Hard Hat dive in many years. "It was like I was back in the Navy Deep Sea Diving School," Harold said. "I feel like I’ve gone full circle."

Today Harold still shows up at the CCED dive meets. He helps tend the young divers and is always ready to pass on what he’s learned over the past half century. The CCED is proud to have Harold Nething as a friend and valued member.

CCED Member - Harold Nething

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