What research for Suunto's Vytec DS Algorithm?

[BigTuna]

I've been looking at Suunto's Vytec DS (deep stop) computer. As the following quote from the on-line manual says, the deep stop algorithm sets the first deep stop at 1/2 max depth below a 10-foot ceiling, the second at 1/2 the first stop's depth below 10 feet, etc.:

The Suunto Vytec allows the user to choose a deep stop algorithm
instead or the traditional recommended safety stop. Deep Stops are
decompression stops that occur deeper than traditional stops, with the
purpose of minimizing microbubble formation and excitation.

The Suunto RGBM model calculates deep stop iteratively, placing the
first stop about halfway between the maximum depth and the ceiling
depth. After the first deep stop has been completed, another deep stop
will be prompted halfway to the ceiling, and so on until the ceiling depth
is reached.

The deep stop length can be set to 1 or 2 minutes.

Enabling the Deep Stops disables the Recommended Safety Stops, but
the Mandatory Safety Stops due to e.g. continuous ascent rate violations
are still prompted.

This differs from all deep stop ascents I've read about, which add subsequent stops at 10-foot increments above the first deep stop, which is placed at 1/2 max depth. So I'm wondering if anybody can direct me to research supporting the Suunto algorithm.

Incidentally, It would seem that the algorithm requires at most only 4 stops for recreational dives. If the max depth is 130 feet and the ceiling is 10 feet, they would evidently be at 70, 40, 25, and 18 feet (it's unclear to me whether a stop would also be required at 10 feet).

The total stop time can be made to be about the same as for conventional deep stops, however. The total stop time for the 130-foot dive would be 8 minutes for 2-minute stops, and 4 minutes for 1-minute stops. For a series of 1-minute stops every 10 feet from 60 feet the total stop time would be 6 minutes. This sort of relationship seems to occur for a 70-foot dive, too. For comparison, the half-time for neurological tissue, which some think is most vulnerable to DCS, is about 12 minutes.

Do you have an informed opinion on the algorithm?

 

[Dr Deco]

Hello BigTuna:

I do not have any information on the Suunto deco programs. It is my understanding that they came from research by Dr Weinke to develop deco procedures for a government antiterrorism detachment. Since this is most likely a clandestine group, the details are sketchy at best.

The algorithm was developed from numerous actual dives (not laboratory dives) and the parameters for the model were determined from an analysis of parameters to produce a best fit. That is my understanding from talking with Dr Weinke and others who have worked with him.

I do not make decompression procedures fro divers any more and do not have any opinion on the positioning of the deep stops. Sorry.:huh:
Dr Deco :doctor: