Poseidon Discovery MK VI - Software Test 48 m Trimix
The Trimix 48 m Firmware for Poseidon's eCCR Rebreather Discovery MK VI has been available for some time now.
Unfortunately Poseidon only provides vague information regarding the underlying computer model,
which complicates the preparation of suitable deco and emergency plans.
For this reason Georg Mück and Sven Böckelmann, both i.a.c. Reabreather-Trainers from the College and Center for Rebreather,
ventured a test dive at the GETASAMED pressure chamber in Dorsten (Germany).
As Rebreather-Trainers it is essential to them to be able to plan and perform authentic dives with proper gas and decompression evaluations.
The test run in the pressure chamber was planned and conducted at 48 m with 60 min. bottom time.
60 min. bottom time was chosen because Poseidon specifies a total dive time of at least 180 min..
Nevertheless members of the College and Center for Rebreather have already carried out cave dives at shallow depths that lasted more than 6 hours.
The intention behind the pressure chamber experiment was to determine the total ascent time and deco stops required for this kind of dive.
Due to the insights gained, future Discovery MK VI Trimix courses can much better focus on certain key aspects.
Another interesting finding was that some tek dive computers are suited very well as backup computer for the Discovery MK VI,
at this kind of dive others just dropped out completely.
For the ascent a runtime with dive profile was provided to Dr. Berndt who was the responsible medic on site.
This runtime was laid out more conservative than the results expected from the integrated computer of the Discovery MK VI,
leading to longer stops and a longer total time to surface, but still very close to the data on the dive computer.
According to the integrated computer of the Discovery MK VI the expected total time to ascent was 83 min. without gas switching.
In consequence of the fullyclosed, fullyautomated design the breathing gas provided was close to best mix for the entire duration of the test dive.
Therefore only relatively short stops and a relatively short time to ascend were required.
The original runtime was calculated based on the experience gained during many dives with the Discovery MK VI.
As a result the total time to ascend was assumed to be 103 min., effectively the ascend in the pressure chamber took 105 min.
For comparison: Using an open circuit system without gas switching a total time to ascend of 409 min. would have been necessary.
With gas switch and EAN 50 a total time to ascend of 119 min. would have been required.
At a respiratory minute volume of 20 l/min about 8000 l Trimix and about 4000 l EAN 50 would have been consumed for this dive.
The gas consumption for the Discovery MK VI Rebreather is about 700 l Trimix and about 300 l Oxygen at a respiratory minute volume of 20 l/min.
These figures do not consider an emergency plan.
About 700 l Trimix and about 2300 l EAN 50 would have been required as bail-out with the eCCR which could be easily carried in a 7 l and 12 l stage.