Sebastien Murat—Interview: Part two
Posted By Peter Scott on 9 November 2002
Freediving Innovation--DRUMS
PS: You take a methodical approach to your own training. And recently, you have applied that same approach to revising the traditional approach to freediving safety with DRUMS (Diver Retrieval Unit and Monitoring System). Explain how the DRUMS works.
SM: The diver is connected by means of a lifeline from the wrist to the surface and lanyard to the guideline, in the case of sled diving, at all times. They can be retrieved at any stage during an emergency at an ascent speed of up to ~2.0m/s, depending on the size and weight of the individual and, power of the topside assistant. The system uses a large diameter, custom-made fishing reel and lifeline. It works on a principle similar to deep-sea fishing. There's no noticeable drag of the line nor is there any tangling. Pre-dive checks of the unit are a ritual; I cannot over stress this point enough.
During the descent the line feeds out freely. With some skilled handling by the dive supervisor it is quite easy to 'feel' for what the diver is doing. In essence, it really is like deep-sea fishing. The specially designed electronic lifeline counter allows us to determine exactly how deep, how long and how fast the diver is moving. With practice it is even possible for the supervisor to establish whether the diver has experienced equalization problems, a blackout or narcosis.
During the ascent the line is slowly reeled in, not so as to aid the diver but only to reel in the slack and ensure there will be no delays in case of an emergency. Of course, during fully assisted variable-weight dives the diver is rapidly retrieved. Control of ascent speed is crucial, especially in the shallow zone where decompression is an issue. The counter is then reset for the next dive at the simple push of a button. The topside supervisor has complete and final control over all phases of the dive such that he may decide, for example, in the interest of safety to abort and retrieve a diver at any time during the dive.
PS: What kind of pre-dive checks do you have to do?
SM: I personally, maintain and check my own gear. Regarding the DRUMS, I ritualistically check it the night before and then again that morning. I check such things as line integrity, reel friction, brake, reel handles, connections, heavy duty velcro wrist cuff, lanyard, reel handle, etc; in short, everything. Paul Murray, the dive coordinator, then runs through his own checks independently.
PS: Is the DRUMS usually mechanized or can it operate by muscle power?
SM: In everything we do we use the KISS method (Keep It Simple Stupid). We've found that it was more reliable to use muscle power. Paul's pretty good for the job of reeling me back in: he's like Tarzan on Energizer batteries, just keeps on going.
PS: Many have voiced concerns over tangling of the line. How do you prevent tangling?
SM: I've never had a tangle; the lifeline is always behind me, dragging. Moreover, it's some distance from the guidelines. We use two guidelines to prevent 'spiral wrapping'. Two guidelines keep me pointed in a straight line.
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