A Hard Choice

The Mark V is an awesome dive boat. It is custom build specifically for diving in the cold emerald sea around Seattle. The Mark V is designed to accommodate 14 divers but since this was a tech charter we only had 7. This was my first time on the Mark V. The dive plan was to do Dalco Wall which is off the south east corner of Vashon Island.

Dalco Wall starts at the advanced recreational depth of around 80ft. There are several small shelves as you go deeper. At 130ft Dalco Wall drops off into an abyss. The joke is that at Dalco wall you can go deep enough to see lights just like in the movie The Abyss.

The dive plan was simple, go down to 150ft for 25 minutes and then do about 25 minutes of mandatory decompression. The gas we would breath during most of the dive consists of 21% O2 35%He with the rest being N2. We add He for 2 reasons. First, He prevents gas narcosis. Second, He being a small molecule leaves the body much more quickly the N2. Helium is also easier to breath. We don't worry about O2 from the decompression point of view because O2 is metabolically active; your body consumes it. For a decompression gas we choose to breath 50% oxygen starting at 70ft. The extra O2 in 50% speeds cleaning up of metabolically inert gasses. We can't breath 50% O2 any deeper than 70ft because it is toxic.

The visibility on Dalco was pretty spectacular, at least 50ft. We dropped off right at a point where there are some underwater pinnacles. The dive was spectacular. We even saw the lights!

I was calling deco. Everything was going well until one minute into our 50ft stop. My buddy lost buoyancy control. Visibility was good so I held my stop and then headed to my 40ft stop. My buddy came back to me during this stop so I held an extra minute for his benefit. He popped a second time. This time I could see him at the surface and we didn't look like he was coming back down. We was still swimming so that was good. If we were to get a serious case of decompression sickness (DCS) that would be really bad. People have become incapacitated and even died from serious DCS hits.

My buddy missed 13 our of 25 minutes of mandatory decompression. I was concerned for his safety. I had to make a hard choice. He popped so gasses in his buddy probably fizzed. I had to place myself in a position where I could be the most helpful for him while also minimizing my risk. I monitored him from 40ft then 30ft. I decided to just do minute stops from 30ft. I cut out 7 minutes of deco, but more important, I would be in good shape and be able to help my buddy if necessary. The boat arrived to pick him up and he was already on the boat when I surface. When I was back on the boat he as already breathing O2.

After the dive all 7 of use that were one the boat debriefed about this incident. My buddy took a fairly hard hit and was really tired. I took a slight hit and was really tired by the evening.