This letter is to address your concern about using your Cochran dive computer on Bikini Atoll. The operators there claim that all of our computers used at Bikini have “failed”. We can state categorically and absolutely that this is a lie. Some Bikini divers have sent us their dive computers for us to check after returning from Bikini and NONE of those had failed. Why the dive operators there insist on libeling and slandering us is unknown. However, we are suspicious since they ban just about all brands of dive computers except Nitek, and they only rent Niteks, sounds like a forced market to us. Even though we could not find anything wrong with the dive computers returned to us for checkout, we replaced some with new units so we could keep the ones used at Bikini as evidence.
To demonstrate how wrong Bikini is, here is one independent assessment of our Dive Computers: Some years ago, the U.S. Navy extensively tested their Cochran Dive Computers at the Naval Experimental Diving Unit and followed that up with extensive field testing over several years. As a result, the Navy’s first Cochran Dive Computer was accepted for use by the elite Navy Seals and is being delivered in quantity. The Navy was so impressed with the functionality, quality, and reliability of that product that Cochran was tasked to develop three more Navy Dive Computers for other operational needs. All of these units are now being used by the U.S. Navy. The Cochran Navy units are the ONLY Dive Computers approved for use by the U.S. Navy. Because of our reputation, many Navies in other countries now purchase Cochran Dive Computers. All of our Dive Computers, including recreational and professional, are manufactured in our facility in Texas on the same production lines and to the same quality standards. Cochran is ISO 9001:2000 certified and our products are CE approved.
Regardless of the vitriolic slander from the Bikini operation, please read the following scenarios for some actual dives at Bikini.
BIKINI SCENARIO #1
As in other scenarios, this is from one of our dive computers from Bikini that the dive operators claimed had “Failed”. The Bikini people had ranted and raved about how ALL Cochran dive computers fail, thereby negatively biasing the diver. Upon returning, the diver was concerned about his unit and sent it to us for checkout. We could find absolutely nothing wrong with his unit. He was using an older Cochran unit that had a “Gauge” mode when a deco stop was ignored. (For many years now, our units have not had a “Gauge” mode.) The following information is based on actual uploads from the dive computer that was on Bikini and interviews with the diver.
The diver begins a typical set of repetitive decompression dives at Bikini Atoll. Based on the diver’s information from Bikini, the dives are generally in the 120’ to 160’ range using air (21.0% oxygen) as a bottom blend and a surface supplied decompression blend ranging from 50% to 80% oxygen.
Looking at the dive computer configuration for dive #1, 2, and 3, the diver programs the unit for 10% conservatism. What he has actually done is told the computer to make every calculation 10% more conservative. What will happen during this type of decompression diving profile is that the diver will have reduced bottom time and increased decompression time. Internally, our dive computers will now calculate an additional 10% nitrogen load for each tissue group and this will catch up to the diver later.
The diver also decides to not change the blend #2 setting which is set at 58.0% oxygen even though the boat will provide 69.0% oxygen for decompression on this dive. Why he did this, we do not know, but this will also catch up to the diver later.
Our computers will do what they are programmed to do, but the diver will complain about too much required decompression compared to his buddies unit. His buddies unit does not have the ability to add conservatism. The diver also told the computer the wrong decompression blend.
This has not only caused an increase in decompression time, but the actual residual nitrogen which the computer has calculated the diver absorbed is based on these inputs. From this point on during this “Dive Day” all NDC, Decompression, and tissue loading factors the computer is calculating are very conservative, even though the computer is functioning correctly based on what it was told. During dive #2 and #3 the diver does not change the computer configuration. Unhappy with its performance, the diver still continues to dive the unit. By the end of repetitive decompression dive #3 the computer has calculated so much residual nitrogen, because of the 10% conservatism and incorrect settings of the surface supplied decompression blend, the unit is now asking the diver for significant decompression time. Furthermore, on this older unit, the decompression obligation is displayed using blend #1 oxygen percentage. If the diver had programmed the correct decompression blend the time would have actually dropped faster than the displayed time once he switched to the decompression blend. However, the diver ignores the conservative decompression obligation, caused by incorrect settings, and goes to the surface causing the computer to go into Gauge Mode, because of the violation of a ceiling. This example is not uncommon when divers do not understand or are not willing to take the time to configure the computer correctly for the type of diving planned. The diver complains the unit failed, when in reality the unit performed as it should with the configuration it was given. This will happen with ANY dive computer, even the one brand that is allowed. The Bikini operators were unwilling/unable to assist.
BIKINI SCENARIO #2
As in other scenarios, this is from one of our dive computers from Bikini that the dive operators claimed had “Failed”. Again, the Bikini people had ranted and raved about how ALL Cochran dive computers fail. Upon returning, the diver was concerned about his unit and sent it to us for checkout. Again, we could find absolutely nothing wrong with his unit. The following information is based on actual uploads from the dive computer that was on Bikini and interviews with the diver.
The diver begins a typical set of repetitive decompression dives at Bikini Atoll. Based on the diver’s information from Bikini, the dives are generally in the 120’ to 160’ range using air (21.0% oxygen) as a bottom blend and a surface supplied decompression blend ranging from 50.0% to 72.0% oxygen.
The diver’s complaint was that the unit was operating normally, but during the final ten foot deco stop it “failed”. During the ten foot stop, the unit was displaying a “10” foot deco stop, and the deco time was counting down to zero. According to the diver, the unit suddenly displayed an 85 foot deco stop, and called for many hours of deco time. The diver, inexperienced at decompression diving, and not reading the manual, misread the display. (Hint: the water temperature was 85 degrees at Bikini). When the decompression obligation was fulfilled, the diver should have noticed that the “CEIL”ing legend had changed to “TEMP”erature, and that the “Deco Stop Depth” was actually the water temperature. Furthermore, the deco time had counted down to zero when the decompression obligations was met, and the legend “DEC” had changed to “NDC” when the display went from a small number of minutes (Deco) to a large number of hours and minutes “NDC” time. The diver complains the unit failed, when in reality the unit performed as it should.
Convinced that his dive computer had “failed”, the diver even took underwater photos of the display where one can clearly see the “TEMP” and “NDC” legends. He was chagrinned and embarrassed when it was pointed out to him. The Bikini operators were unwilling/unable to assist.
BIKINI SCENARIO #3
Upon returning from Bikini, a very experienced diver wrote us a letter regarding that operation and his Cochran Gemini he owns and uses. It was a week of diving with up to 12 decompression dives. He had read some negative remarks regarding Cochran computers and diving at Bikini Atoll and contacted us before his trip. His report states “My experience with your [Cochran] technical and customer support staff has been one of the most pleasant of my rather long life. THANK YOU…”
We quote from his report:
“Bikini Operations: On arrival, we were given a briefing where our general level of training was verified by the Head Dive Master ([name redacted], previously of Dolphin Scuba in Sacramento). He checked our certification cards, and announced that the only certification he personally has any respect for is that of a “Full Cave Diver”. That was rather amusing to me, since there aren’t any caves around here that I know of. He also asked what type of equipment we were using, and noted that those “piece of junk Cochran’s NEVER make it past the 3rd day, and he’d be keeping an eye out for me when it quit”. I find that type of reassurance to be just what someone needs, especially when they’ve paid over $3000 for 12 scuba dives. Oh, well…. Note to Mike [Cochran]…. Did you ever scare this guy’s mother while she was carrying him in her womb?????”
“The other 2 Dive Masters, much younger Americans, seemed to be less doom and gloom about things, but also shared the sentiment that the computers wouldn’t make it. One fellow, [name redacted] ([name redacted] Diving Duds in West Chester Pa.) was very strong in his belief that diving the Cochran computer was pure folly. I found it curious that he would be against new stuff, since I remember diving with his mom about 30 years ago, and she was quite the daredevil.”
“The third Dive Master, [name redacted], seemed to be rather neutral, and stated he didn’t know enough about them to comment one-way or the other, but couldn’t see it causing any problems.”
This diver goes on to report: “In order to ensure safe operation throughout the rest of the trip, I elected to “sit out” your Gemini for the first dive on the 3rd day (the “DAY OF DOOM for the Cochran’s”). My poor old tired [Cochran] computer worked just fine, recording deco stops within 1 to 2 minutes of my dive partner, who was using a pair of Nitek’s (a “3” and a brand new “HE”). This continued throughout the week with us never being more than 5 minutes apart on any stop. I noted that generally the Cochran’s cleared a stop level earlier than the Nitek’s. I would believe this is due to the air data, which is not accessible by the Nitek. The other side of this is that [name redacted] said, “I can’t see any reason why anybody would want to have air data. We certainly don’t need it.”.
Note: This is where we disagree with the diver and Bikini. The Cochran Gemini is an air integrated Dive Computer that accurately measures cylinder pressure and computes gas flow. Based on this information, the Cochran Gemini computes the divers Workload and automatically compensates the Nitrogen Algorithm.
This diver goes on to report: “I returned your Gemini to the operation on the afternoon dive, and noted the appropriate differences between the 2-deco stop requirements. This is to be expected due to the higher nitrogen load recorded by my computer, which was now 1 dive ahead of the demo unit. These differences continued until the 5th day, when they seemed to even out. My dive partner incorrectly set his Nitek-3 to the deco mix of 78% from the surface, which caused the computer to give out continual warnings for high O2 PPO, and then shut down and refuse to work until the next day. I don’t know what the magic is in the hour of 12 midnight, since if you really tried to do 140 feet plus on 78% O2, you’d be long dead by then. With our [Cochran Gemini] gas switching being done automatically, I don’t think it’s possible to have this type of problem with the Gemini??? [He is correct.] Anyway, since he was down one computer, I lent him the demo Gemini to use. He was favorably impressed with the ease of use; given the minimal instruction I gave him. “Hook up the air to the high pressure port. Hang the display on your BC. Do what the computer tells you to do regarding deco stops. It brought him back alive and safe, and with the stops falling within 1-2 minutes of those called for by the Nitek HE.”
“Another of the divers neglected to manually change to his deco mix upon arriving at the “bar”. This resulted in the Nitek thinking he was still breathing air, and leaving him with over an hour of extra decompression. Another problem, which can’t happen with the [Cochran] Gemini.”
“About mid-way through the week, I noticed a peculiar ‘dance’ being performed by all the Nitek divers. Immediately upon returning to the boat, they lined up to use the fresh water hose to wash off their computers. I asked why the concern for the computer, and was told the Nitek sometimes doesn’t know you’re out of the water if there is salt water between the contacts on the face. I thought the computer knew it was on the surface because the pressure/depth indicated it was on the surface??? Just silly of me, I guess. My [Cochran] Gemini only gets rinsed off when I get back to the house/cabin/room, and seems to realize it’s on the surface. I don’t think I’m harming it.” [He is not.]
As a summary, the diver goes on to report: “The Cochran units performed without failure or abnormal indication throughout the entire 12-dive program. My “clearing” and “stop” times were shorter than those of my partner who was using Nitek’s I would expect that due to the air-data being used in the computations. The computer units worked well, with no alteration of parameters by me once on the atoll. Although the deco mix varied between 75 and 79% O2, I left the setting for it at 75%, and did not change it at all. I have supplied the WAN files [from the dive computer] for both units as an attachment to this email, and would appreciate your review and evaluation of them.”
The diver finishes by making some suggestions for the future.
