Visibility in the Channel

We got up this morning and loaded the boat, excited about what the days diving had to offer. The sea was very calm, although once we left Portland Harbour, the fog was causing a little concern.  It was warm already, so we figured it would burn off in due course.

We arrived on site at about 1130, and Smudge got the shot in in good time. Rich and Os planned a longer bottom time, so jumped in first to find a surprising amount of surface current. After a brief rest on the surface they descended the line and found that the shot had been pulled out in all of the exertion. It had fortunately left a nice deep score in the seabed though, so after tying in a line, they swam up current and connected with the wreck making the next teams job a little easier.  This was also done with 1-2m visibility and no ambient light, so the dive was starting to get difficult already.

The second team, comprising Paul Burgess, Michael Puz and Darren Morley soon arrived on the line but were unable to find the survey lines from our dives in 2010 and 2011. These were in place in 2012, so this was a big disappointment, as they make navigating the wreck so much easier. They headed off to work out where they were, soon arriving on the bow, and realising that this was not where they wanted to be as their job was to survey the break in the hull.  Turn around and head the 70m back.

Rich and Os' job was to look at the bow section and work out whether any vehicles could be seen from the entrance, as we've not managed to get inside much in the past. There was definitely a way on in this area and Rich tied in and started moving in, at which point his light failed.  In 1m visibility, inside the wreck. Os helpfully handed him a backup light and a few minutes was spent peering around to see what was going on. Access into further areas is very likely possible, and Rich fancied that he say a truck tyre at the end of his light beam.  Maybe, maybe not. Either way, they turned tail and fled as it was too far inside a wreck to be messing around on a back up light in poor visibility.

Heading back along the wreck, they passed the LCVP davits, propellors and engine. LST531 sank so fast that she was unable to deploy her LCVP's as lifeboats.  A large hole in the hull was also spied, which hadn't been noticed on previous dives. Paul, Michael and Darren had also come across the same hole, and it may well be the site of one of the torpedo strikes.

The poor visibility had made any kind of quantitative survey impossible, so unfortunately both teams returned with little more than stories and observations. No sketches, but despite that, we have been able to put together a small sketch of the site.

We were very privileged to be joined by Stew Waring from the SHIPS Project in Plymouth.  These guys have some very clever tools and techniques for surveying shipwrecks, and Stew was kind enough to share some insight and give us some advice on how to conduct or survey work.  After our discussions back at Scimitar Diving, we now have a decent strategy for surveying the break, looking in more detail at the torpedo hole, and also to photograph one of the 2.5 ton trucks.

Distances are one of the things we haven't paid enough attention to in the past, and most of are surveys are very qualitative. We aim to rectify this, and one strategy we use is to lay line, knotted at 1m intervals. Boring job, so we made Os do it.

Tomorrow, we will be joined by a handful more divers, and we will hopefully be more productive.

A great day, and more fun to come tomorrow!