Just a quick update, some photos and video from our practise day at Vobster.

In the end 5 members of DIR-UK team turned up to run through survey techniques and generally have some fun in preperation for the summer's revisit to the unkown sailing ship.  Alastair shot some video and had some fun editing it  -you can see it here.

Practice of survey techniques comes in useful in other arenas too so was worthwhile - as well as getting together with some nice guys and going diving!

Dive 1 we had two teams. Team 1 was myself & David - who layed a line course which David then surveyed. Joe played sheepdog in team 2 while Marcus and Alastair surveyed.  David Martin and I first laid some line which the teams could survey - both a mainline and cross over lines as in wreck surveying running lines off to othere areas of interest is pretty useful and we need to be able to track these positions on the survey map.  Each time a wrap is made a 'station' is formed where depth and distance can be recorded allowing usa to make a stick map of the site.   

A little debate ensued as to how to reference cross lines but we decided to form stations at these junctions by dropping markers which could be referenced in notes. On dive 2 we again had two teams and Alastair spent his time switching between the teams while shooting video. Team 1 was Joe and David who surveyed the line but this time took a measuring tape to see what improvement of accuracy we got compared to the survey on the first dive. Joe ran the survey while David used the tape. Team 2 was me (survey) and Marcus (tape).

I felt we learnt several lessons which will help on the Unknown Sailing Ship dives later this year. First off was that the cave survey sheets while good had boxes to allow you to indicate the size of the cave passage. We might be better off using a slightly different format to more easily identify wreck features.

Secondly we seemed to find that any point where we created an intersection with another line with a line arrow we were best off treating that as a new station on the survey. It would lead to less confusion when it came to mapping.  A couple of the others commented on having their hands full so I think the idea of the compass mod Al has done prove to be useful as shown below

The principle is that by making the pencil and compass one item underwater then it's easier to manage taking the survey points, entering the data and keeping moving. The pencil just pulls out of the cable ties so you can stow it separately.

David’s work knotting line at 1m increments was very successful and did seem to offer us enough accuracy combined with estimates to let us produce a solid map. If needed though we can take the tape measures on a dive.

Alastair and I spent both dives on the RB80’s which was good opportunity to keep building the hours on the units and expose a few more members of the team to diving with RB80s as we will be mixing teams later this year.