Building my very own Megalodon.
On December
6th, 2004 I
showed up at Innerspace Systems Corporation for the first day of Meg
building. Leon Scamahorn and Steve Stolen are the CEO and VP of the company, Brian
does most of the sewing and Ruby keeps
the paperwork flowing. This is not a
huge operation, but the numbers keep creeping up and it wont be long before
there will be a need to be in a larger building. The month of December saw 15 Megs go out the
door, pushing the total to around 160 units in service.
ISC was in the
process of earning ISO certification for their manufacturing and as of this
writing it has been completed. The first
time they were audited, they passed with an unprecedented 100% perfect
rating. The auditor was very
impressed. Frankly I expected it, when Leon puts his mind to something it will get
done. The care and expertise that goes
into the design and build of a Meg rebreather is nothing short of
astounding. In the past months I have
spent around 4 weeks at the ISC shop (working on my Meg technician) and have
learned plenty about how the units are put together. An example might be the wiring. Most places would be satisfied with crimping
the tiny wires into Molex pins and then snapping them into the plugs. These plugs are used on the O2 sensors, the
battery packs, and in the handsets, all dry places (excepting the
sensors). ISC assembly instructions specifically
require that these wires be measured by ruler, the ends stripped of insulation
to specific lengths, crimped to the pins, then hand soldered before being
inserted into the plugs. This extra step
of soldering ensures that the connections will remain tight, even though it
takes much more time to do it. I have
spent several hours doing exactly that, under magnification. In building 20 sensor carriages, I cut,
stripped, crimped, soldered and clipped 120 pieces of wire. Every one of them must be perfect, not only
was I working on my own rebreather, but other customers units too. All this time I was under the watchful eyes
of Leon and Steve.
Dutifully hooked up to a static grounding
system, I assemble my head plate to the electronics pod and handset
cables. Before touching anything
electronic in the shop I had to take a short course in static control.
When Leon told me I was going to spend a whole week
building my meg, I had trouble believing him.
I have been building things with my hands all my life, my skills were
aplenty, I could solder, use hand and power tools, and knew things about
electronics that most never learn. It
still took a week. By the end of the
week I had learned a lot. Mostly that
there are three ways of doing things.
The right way, the wrong way and Leon’s way, which is better. There is a reason that the Meg is the finest RB on the market, (IMHO) also one of the most expensive. That reason is summed up in the word
“meticulous”. Even after each Meg is
complete, it goes through a 43 point checklist, every function is tested, valve
actuated, and button pushed.
Here I am standing next to my very own meg,
rigged and ready for my first pool session.
That pool session lasted 4 hours, it was like a gym circuit course,
three of us students swam around the perimeter of a pool, at each corner we
preformed a skill, Boom scenario, flood drill, gas loss drill and more. Buoyancy control was mandatory, and we heard
about it if we bumped off of the bottom.
Steve Stolen, the electronics brain builder,
is the father of the Apecs II electronics setpoint
controller. He is retired from Boeing,
where he worked on embedded software for airplanes. The Shearwater electronics system for the Meg
was designed by Bruce
Partridge and
shows up at ISC as assembled boards, ready for testing and potting. While we are on the subject of electronics, I
should mention a bit about ISC philosophy.
Redundancy is the watchword. The electronics systems used in the Meg
consist of a primary system and an secondary system. The Apecs II has
two handsets and an optional HUD, (although almost all units go out with it)
the electronics boards are completely separate, although potted into the same
physical block, the only commonality is the sensors themselves and even those
are electrically isolated. Two battery
packs, separate circuit boards, and separate handsets ensure that even if one
handset is destroyed, flooded, or even cut off, the second system will continue
to work. The wire the handsets are
connected with costs $16 per foot. It is
military spec wire that will not transmit water through its length, so even if
the handset gets flooded, it will not introduce water into the head of the
unit. The Shearwater is designed the
same way, but only has one handset and a standard HUD as a secondary. If the primary system fails (which controls
the solenoid) you may still fly the unit manually using the HUD to monitor your
PO2 levels.
The HUD is simplicity
itself, a single tricolor LED sits in a sealed housing, just in the lower
vision of your right eye, attached to the DSV.
It blinks a pattern to let the diver, or his buddy, know what the PO2 is
in the loop. For 1.0 it blinks orange,
three times, once for each sensor, then a pause, then three blinks again. For any value above 1.0 it blinks green, for
example, at a 1.1, you would see three green g,g,g,,,g,g,g,,,
blinks, for 1.2 you would see three sets of 2 blinks, like this gg,gg,gg,,,gg,gg,gg,,, and so on, at 1.3 it would be ggg,ggg,ggg,,, with the ‘g’s being green flashes and the
comma’s being pauses. This would
continue to be true until the PO2 reaches 1.8 where the LED goes solid green,
so G,G,G,,,
For values under 1.0,
the LED blinks red for each tenth of a point under 1.0. So .9 would be r,r,r,,,r,r,r,,,
.8 is rr,rr,rr,,,rr,rr,rr,,, any value below .2 the LED goes
solid red, R,R,R,,,R,R,R,,,
I have the Shearwater
electronics and I have to say it is a nice bit of kit. The software works as well as any product I
have ever owned, never even a hiccup or weird screen, the setpoint stays right
where it belongs and the deco info is very consistent and stays very close to
my VR3’s information, even if they cannot agree
on stop depths. I follow the most
conservative unit during my dives, which is usually the VR3 because I keep the VR3
setpoint on 1.2, the Meg on 1.2 also, while I fly the unit manually a bit
higher, which the Shearwater is aware of and the VR3 isn’t. Calibrating the unit is
very easy and if you trap the O2 into the head, with a dust cap and a cap on
the scrubber end, it removes the necessity of flooding the entire loop with O2,
thereby saving gas and getting a more solid calibration.
I really like the
ability to plumb additional gasses into the Meg, there is an option to add in
another gas injection valve and I highly recommend it. This puts an injection valve in your exhale
counterlung where you can plug any cylinder that has a LPI hose into it just
like a drysuit valve. This allows
jacking into a sling bottle of trimix, or a buddies off board gas, or even an
open circuit divers air supply in a pinch.
For long excursions a diver can change out sling bottles, or change out
mixes for different depths of the dive.
The only limitation to length of dive is now thermal, or scrubber
size. The stock scrubber that comes with
the Meg is a 4-6 hour unit, depending on how cold the water is. Recently
ISC has signed an agreement with Bill Stone, the inventor of the Cis-Lunar RB, to begin building the famous Cis water tolerant scrubber for use in
the Meg. This is an 8 hour radial unit
and Leon is also working on a 10 hour unit for the
really serious players. There are some
cave divers who are side mounting two megs with separate loops for total RB redundancy in those really deep penetrations.
Part of my Meg
technicians course is oxygen cleaning.
No stranger to O2 cleaning myself, as I do it with all the fill whips I
make and the thoroughness that ISC is famous for continues here. Every fitting is taken completely apart,
springs, o-rings, lock circlips, even things that will not come into contact
with O2 are ultrasonically cleaned, rinsed with filtered hot water, dried off
with “Safeair”, examined under UV light, put into plastic bags, sealed and labeled until use. Even the Apeks
regulators are taken apart and cleaned before being installed onto a Meg.
Ok, I took a break
from writing this and am now back at it, today is 23DEC05 and a few things have
changed. ISC is no longer offering the
Shearwater system and only offers the Apecs 2.0. There were some problems with a few
Shearwaters and Leon is taking care of the owners of those units. Mine is still working ok except a couple
dives the depth sensor did some weird stuff, not properly tracking my depth and
causing excessive deco compared to my VR3. It has since been acting fine. I have also taken a head plate and built a
COPI head out of it. What COPI means is
Constant Oxygen Pressure Injection, basically its like the KISS system but
replaces the solenoid with an orifice, caps the first stage of the oxygen reg
to provide constant IP to the orifice and I built a Meg handset with three Datel millivolt meters in it with a backlight so it reads
PO2 of the three sensors in the Meg’s head.
This was built as a backup to my Shearwater head if it ever failed on a
trip or expedition. Since I built that
head I met Patti, an open circuit diver who has an interest in CCR’s, I trained her on the Sport Kiss and she was going to dive it for a
while until she could afford a Meg. Well
she came into some extra dough and I ended up building her a MiniMeg using the COPI head and now she is diving that, so
I guess I need to build another head. :
)
At Innerspace 2005 in
Cayman this year I was tasked with showing off the Meg and some new
developments as Leon was unable to attend, I was allowed to bring and dive the
new 7.5 lb radial scrubber pre prototype (no hydrophobic membrane) and showed
off the COPI Head I have been diving and testing. I also showed off and displayed some of my
own goodies like the Draeger Backplate conversion, Fill whips, and CCR Dolphin conversion kit that I still have not put into production
(sigh, I just don’t have enough time in my days)
So, in conclusion, I
can heartily recommend buying, owning and diving a Meg rebreather, the unit is
just solid, well designed and extremely well built, you can make an appointment
and go build your own unit, or just have one made for you if you don’t feel
that mechanical, its not cheap, but rarely is anything of quality. There is a wait time involved but it is down
around 2 months now, there are 3 more employees at ISC now assembling and
testing units so things are happening faster now. Contact Leon to order your very own Meg. The website is www.customrebreathers.com
Here is a Picture of Patti with her new MiniMeg COPI.
Ron Micjan
www.tmishop.com
6MAR05-23DEC05