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I'm taking the liberty of posting some information about
the new Nemesis II, mostly written by Mike Cochran. It's
not been editing or abridged, and some of it is an
answer to a question, so keep that in mind as you read it:
========================================================
What follows is a partial "feature" list used to prepare the product
advertising.
- Engineered for extended working depths (250' nominal operating depth plus 80'
cushion)
- Engineered for extended tank pressure. (5119 psig)
- True hands free operation. Proprietary inertial sensor accomplishes mode
change with a flick of the wrist.
- Dual programmable O2 blends with automatic tank change sensing (Nemesis II
Nitrox)
- Intelligent deep dive compensation analyzes previous dive data to accomodate
inverted dive profiles.
- Temperature, workload based NDC compensation.
- Ascent rate based NDC compensation for micro-bubble formation.
- Full decompression stops to 60 feet with compensation for extended stop
times. Internal 100 foot model reduces model violation.
- User adjustable conservatism.
- Seamless altitude acclimatization (even when "off")
- Manual AND auto activation.
- Intelligent power management provides extended life from inexpensive user
replacable batteries.
- Extensive user customizable & audible/visible alarms including:
- fixed or variable ascent rate
- 1/2 tank pressure
- five minutes remaining air time
- 500 psi remaining air
- two minutes remaining ndc time
- pre-set depth alarm
- Depth less than decompression ceiling
- computer entering guage mode
- User customizable historical data logging intervals from 1 to 20 seconds.
- Glass-fiber reinforced aerospace polymer cases engineered to withstand the
most extreme conditions
- User selectable Imperial or Metric (Kg/sq cm or BAR) units, depth shown to
nearest foot or 1/10 meter
- Automatic sea water / fresh water compensated depth reading
- Variable profile storage intervals (1-256 seconds)
- Maximum dive summary storage: 3495 hours.
- Maximum dive summary storage: 350 dives
- Custom tunable with the most extensive set of PC interface tools on the
market.
- Legendary Cochran service and reliability.
------------------------------------------
What technical specs do you like about the Air-X? After two years of attempts,
we finally purchased one for competitive study and are frankly, underwhelmed.
We have not seen (in the manual or anywhere else) any written specs on the max
depth or max tank pressure, or any other specs that you can hang your hat on.
You can listen to your dealer, but the one from whom we purchased our Air-X
'invented' a bunch of features which the Air-X didn't have. (He didn't know
who we were.) All we have seen is some expensive ads and marketing hype much
of which is just not true. When the Uwatec ads first started appearing, I
wrote a letter to the President of Uwatec in Switzerland about this, but have
yet to receive a reply.
You have raised some interesting issues, and I'll try to respond to some
of them if you will bear with me. We agree with you that computers should be
able to 'know' many dynamic variables and adjust it's algorithm in response.
After all, we have been producing just such a model for some time now. Our
NEMESIS-Nitrox and the European version of the NEMESIS has pioneered the
temperature and workload compensation of the algorithm as well as the user
setable conservatism, in spite of Uwatecs claim to the contrary. In fact
(unlike the fixed Air-X) the temperature effects can, and should be, turned off
if you are using a warm dry suit. Also, the workload compensation can be
turned off (unlike the fixed Air-X) if the breathing rate will be seriously
affected by factors such as carrying an extra tank or using your main cylinder
to fill a lift bag. In addition, the cylinder size can be entered (unlike the
fixed Air-X) because cylinder size can also seriously effect the workload
computation. These features, and many, many more are also incorporated in the
NEMESIS II which will start world-wide shipping next month.
I would be remiss if the users of Air-X were not cautioned about a problem that
we encountered while testing it. Note that it transmits tank pressure only
once every five seconds. Note that neither the tank unit nor the wrist unit
has a replaceable battery, so we believe that design compromises had to be made
to shut units off quickly to extend battery life. Note that the 'loss of
transmission' symbol is very small and only comes on after a long time. Put
all these together like that Air-X does and you have the scenario that was
encountered. You look at the wrist unit just before a dive and it says 3000
psi of tank pressure. Unknowingly, your tank valve has been turned off, but
the high pressure hose is still pressurized. You jump in the water and
descend, but run out of air after a few breaths. While buddy breathing, you
look at your wrist unit and it still says 3000 psi. After a long period of
time, the little 'transmission loss' symbol comes on, but the tank pressure
still says 3000 psi. What happened? The tank unit detected that there was no
tank pressure and turned itself off, thereby leaving the wrist unit displaying
3000 psi. Now, I'll admit that most experienced divers would never jump in the
water without grabbing a few breaths to ensure that everything is functioning
properly, but it does happen, and I've personally seen it.
While I'm on the subject of the Air-X and tank pressure, I just can't believe
that any modern dive computer requires the user to carry a conversion chart to
convert the displayed tank pressure to actual tank pressure as a function of
temperature. Yeah, thats right! You read correctly. It's actually in the
Air-X owners manual, and they don't even have the courtesy to give you a
waterproof conversion chart to carry.
There is FAR, FAR more that I could go into, but let that wait for a while. In
the mean time, I would like to objectively list the features of the Air-X that
we admire and are, honestly, better than the NEMESIS (II):
1. It's prettier.
--------------------------------------------
* Nemesis 'model' is Haldanean based and has twelve compartments. We have been
producing the NEMESIS for almost two years now and have accumulated an
impressive number of detailed dive profiles and dive summary data. (Remember
that the NEMESIS stores an extremely detailed profile and MUCH data about every
dive.) We encourage users to occasionally send us a disk with their uploaded
dives so that we can add them to our growing library. Anyway, the modiications
and improvements that were made to the basic model were based on this extensive
library, work we did for NASA, and much public domain literature by a number of
authors including Bruce Wienke and Bill Hamilton. The model 'modifications'
were done by our staff here at Cochran Consulting, Inc. You may not be aware,
but we have a very complete and experienced product development staff. Unlike
most other dive computer 'manufacturers', we do the COMPLETE product here from
concept thru software, mechanical, electronic, and manufacturing. Ask Bruce
and Bill, they have both been to our facility.
* The NEMESIS II tank pressure alarms are quite simplistic and are intended to
be like 'Oh, by the way, you are now at 1/2 tank pressure' or 'Oh, BTW, you
have only 500psi of air left' <G>. Not intended to be an absolute indicator
of
your air remaining, or save the diver from stupidity. The NEMESIS II does
display 'Air Time Remaining' all of the time, though. Among other things, it
also lets you know when your remaining air time is within five minutes of your
total decompression obligation.
I did not want to scare anyone with the many features of the NEMESIS II. It is
actually VERY simple and easy to use. It has large, easy to read numbers and
additional information can be seen on an alternate screen by the flick of your
wrist. Let me point out that YOU DON'T HAVE TO USE ANY OF THE ADVANCED
FEATURES OF THE NEMESIS II. It comes preprogrammed for the average diver. If
you wish, your dealer can reconfigure it for you, or you can do it yourself.
We have an addition piece of software (free) that takes the user through a
bunch of very simple questions and automatically configures the NEMESIS II
based on your responses. BTW, this 'configuring' of the NEMESIS II is
semi-permanent. It won't change unless is is altered intentionally. HOWEVER,
as the NEMESIS II comes out of the box it is a 'nice, compact and highly
automated package'. (It's also less expensive than the Air-X.)
To address a couple of your other points:
We have greatly extended the battery life of the NEMESIS II wrist unit to over
two years of heavy use. It uses a pair of inexpensive alkaline 'N' cells. The
battery compartment has a dual o-ring seal, and can be flooded without damaging
anything (except the batteries). The Tank units battery life has also been
extended and uses four 'AA' alkaline batteries in two compartments that can
also be flooded without damaging anything. I just walked back to our Customer
Service Department and asked how many battery compartment floods had they heard
about recently, and they said 'only two'.
Regarding permanently sealed batteries, in my opinion, this an old technology
and scares the hell out of me. Regardless of what any manufacturer says, I
just don't believe battery life estimates. It is too dependant upon a variety
of factors such as:
battery condition when installed
time between manufacturing and sale
the divers diving style
number of audible warnings
temperature.
(We eliminate the first two variables by including a VERY fresh set of
batteries in the box while the NEMESIS II has 'shipping batteries' in it. Our
dealers have instructions to put the new batteries in the NEMESIS II (not the
dealers walkman) before delivering it to the end user.)
Since the Air-X has only a twelve month warranty, I personally wouldn't plan on
the batteries lasting any longer than that. When we bought our Air-X we asked
how can we get the batteries changed, and were told that the unit had to be
sent back to Switzerland. <Scary> Even worse, the Air-X is PERMANENTLY
sealed.
I don't know how they are going to change batteries without breaking open the
case. No one would tell me the cost of battery replacement. <VERY scary>.
I believe that the real reason some dive computers have non-replaceable
batteries is related to the case design. There are two approaches to case
design. The Air-X type is actually a fragile case that is oil (or gel) filled
to sustain pressure that is equally applied around the entire unit. If
subjected to uneven pressures from outside mechanical forces (like on a dive
boat) it can break quite easily. (I wouldn't accidently step on it.) The
other design approach (ours and others) depends on strong structural integrity
which includes the actual design and materials of an air filled case. This
approach results in a very strong case that can withstand abusive environments.
As a test, we took one NEMESIS II wrist unit, its companion Tank Unit, one of
our Commander dive computers, and one of our Captain dive computers and placed
them under each wheel of a company van. No damage to either the dive computers
or the van or the driver. NOTE: This was done by 'professionals' who routinely
drive company vans over dive computers in company parking lots, and you should
not attempt it yourself.<BG>
-- Robert
--------------------------------------------
E-mail: RLaird@pe*.co* (Robert Laird)
Phone : 713-627-4323 Fax: 713-989-3086
Trunkline Gas Company, a subsidiary of
Panhandle Eastern Corporation, Houston, TX
--------------------------------------------
12/19/94 10:29:37
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