Last Tuesday I selected a less ambitious dive site for an evening dive after work. I loaded the dive gear on my 7.8m RIB boat and it took me less than an hour at 45 knot speed to arrive at a wreck site previously unknown to me. I soon located the freightship with my side-scan sonar and then threw my anchor to the port side of the wreck. I then let the slight stream settle the anchor and 100m of anchor line. Then I noticed that the anchor line lead into the water at a sharper angle than expected and had a different feel to it. Perhaps the anchorline had caught into the superstructure of the wreck.
In advance, I knew that the visibility might be very poor. At the surface, the visibility was 1-2 meters, good enough for me. I donned my dry suit and kitted up with a twinset and a stage tank. Whilst descending, the visibility was lost completely at 15m depth. The water was a thick milky fog. I could not even see the glow of my 2000 lumen lamp if I held my hand straight. I was not too concerned about this due to my cave training and earlier experiences of similar conditions. However, I could not read any of the gauges or my dive computer even if I placed them against my mask.
I felt relaxed and so I continued with my dive. I soon reached the bottom where my anchor line had jammed just under the bow of the freight ship. I released the anchor line and then followed the line to my anchor just to make sure it was secured and could be pulled away later. I then returned back to the wreck and wondered what next. I decided to explore the front section of the wreck by touch only. I followed the gunwale and drew a mental map of everything I could reach and feel. I was cautious in this exploration because I did not want to get entangled. Since I could not measure time nor check my gauges I hesitated to go too far and soon thumbed the dive.
I then followed the gunwale back to my anchor line. Visibility was still absolute zero, i.e. I could not see bubbles, particles or anything else in the water. Whilst ascending I would have no idea of the depth, so, I made myself slightly negatively buyoant and hanged from the anchorline. Then I slowly climbed the anchorline until I reached 15 meters depth with some visibility. Run time so far was 30 minutes, much less than planned. The remainder of the dive was uneventful.
Whilst stowing away my gear on the boat, I noticed how little I had consumed gas. I was a bit surprised that my calculated SAC rate was less than on an average dive. Well, this was a relaxing solo dive. I smiled happily as I drived my boat back home through calm and unpopulated seas. Apart from me and the coast guard vessel, there were no other boats in the growing darkness.