125m TG Walchensee Gallery June 2007

Team: Roland Kring, Robin Sporrer

Saturday, the 23.06.2007

A rebreather-TG at the gallery was planned by us and was successfully accomplished on 23.06.2007. During this dive we will reach a maximum depth of 126m and at 122m we will find the corpse of a sport diver. During this dive we estimated a bottom time of only 10 min at an average depth of 110m due to the current thermocline situation (cold). The descent time was not considered in the bottom time. This TG was performed with RB 80/RB 2000 and double 20 with Trimix 12/75. The back gas in the double 20 served as safety gas and was not used during the TG - except for inflating the wing and for the gas breaks.

The primary gas source for the bottom time beyond 54 m was a stage (80 cbf) with a Trimix 12/75, in addition 4 deco gases in 80 cbf stages were used. Most of these were standard decompression gases (O2, 50/25, 35/35) with the usual MODs and, as an "exotic", a 25/45 with a MOD of 54 m set by us.

As a regular 4th decogas, a Trimix 21/35 is given in the relevant literature and in some TG reports, which is usually used for decompression from 57 m depth. Due to the He- and N2 drop that seemed unfavorable to us when switching from the bottommix (12/75) to the deco gas (21/35 -> 25/45), we decided, after various considerations regarding better deco quality, to use a Trimix 25/45 as the 4th deco gas, which we used starting at a depth of 54 m. In addition, we used this gas to descend to 54 m from a depth of 15 m on the rebreather.

The TG was therefore carried out with 5 x 80 cf stages and a heating tube for the supply of the 80 W or 100 W heating shirts, underwater support was not available.

Initially, the RB 80 was supplied with the Trimix 25/45 as "travel gas" during the descent and the scrubber was first breathed warm at the water surface. Subsequently, the descent OC was initially to a depth of 15 m, there was changed from OC to the RB and after the RB check with the 25/45 to a depth of 54 m, the scree was descended in the direction of the wall. At 54 m we changed to the stage with the Trimix 12/75 followed by the further descent. We passed the usual "sights" on the way down (Paulaner flag at about 80m, car wreck at about 93m, cross at about 100m) and kept descending the scree slope, moving about 10-15m away from the end of the wall. At 122m we sighted the corpse of an unknown recreational diver lying on his side half covered with silt and equipped with a first step and a mono-bottle. We circled the corpse, reaching a maximum depth of 126 m, after which we raised our thumbs and dove back to the steep wall, starting the usual deep stops at 94 m near the wrecked car and initiating the decompression phase. At 54 m, the change from trimix 12/75 to the first decompression gas 25/45 was made, followed by the change at 36 m to the second decogas 35/35, at 21 m to the 50/25 gas, and finally the change to O2 at 6 m depth. In each case, gas breaks with the Trimix 12/75 preceded the gas changes. At 6 m, breaks were performed with the back gas in a 12:6 ratio.

For the TG we used a Bühlmann based profile with GF low 0.1/ GF high 1.2, whereby we decided to cut about 10% of the 6m stop on the deco. The deco worked for us without any problems, unfortunately there was no Doppler available with which we could have objectified this, but the wheat beer and the sausages in the evening tasted good ;-)

Thanks to Holger M, Stefan G, Tibor, Andy for taking the stages and helping out of the water. Really super nice from you

In October 2007 the Kripo was at Roland's house and played him some U/W video sequences they made with the ROV. The police came relatively close to the corpse. It is to be seen on the video e.g. the wire mesh fence on approx.
120m to see. The corpse was max. 3-4m away from the fence. Unfortunately, since they "drove" the ROV in the wrong direction from the fence, they could not find the dead body. Since I knew the place however still very exactly, I could make exact data on the basis the video.

Unfortunately I (Roland) am not allowed to show the video shown to me.

In this sense,

Your Cavebase