Hi All,
Just a quick update on our practise day at Vobster. In the end 5 of us turned up to run through survey techniques.
Dive 1 we had two teams. Team 1 was Clare & David - who layed a line course which David then surveyed. Joe played sheepdog in team 2 while Marcus and I surveyed.
On dive 2 we again had two teams and I spent my 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 Clare (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.
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. A couple of the others commented on having their hands full so I think the idea of the compass mod I posted about the other day would be useful.
Clare and I spent both dives on the RB80’s which was good opportunity to keep building the hours on the units.
Anyway here’s a quick cut of some of the video. It’s the first one I’ve done other than some skill demos so don’t be too critical!
YouTube - DIR-UK Survey Practise April 2008
Cheers
Al