The Monument mapping

We went to map the monument site yesterday as part of our Dive Master course. We have done 2 previous familiarization dives on the site and we sat down to plan the best method of mapping the site.

Due to various circumstances there were only 3 of us available to map that day so we had to dive as a group of 3.  My dive buddies were Gemma and Garth.

The whole dive plan took well over an hour but after a great deal of discussions, scribbling, head scratching, crossing out and redrawing we eventually came up with a plan that we all agreed would work. The plan was to descend in about 3M swim North until we dropped over the wall, then swim to the deepest part of the map and drop a buoy. We would then swim perpendicular to the wall away from the buoy for about 7M with a rope and drop it weighted at that point.
We then planned to swim back to the buoy and swim the length of the wall while Garth counted his fin cycles. When we reached the other end of the wall we would repeat the same procedure with a second buoy. This would give us a 7M x dive site length rectangle to map.
The plan was then to set of on a compass heading + 90 degrees from the perpendicular bearing ..... You can see why we had a lot of discussing to get this plan together.
We would take depth and geographic references every 2M and swim the rectangle in a 'U' pattern.
Finally  we would ascend at the first buoy and take a surface bearing on the 2 buoys to measure the angle of our map in relation to the compass.


View The Monument dive mapping in a larger map

Anyway we got in and were nearly swept out to sea in a 7 knot current and quickly called the dive off. We realized there was no possibility of being able to map the site today with the strength of the current. Apparently there was a king tide or something similar and the volume of water leaving the bay 30 minutes after high tide was incredible. We had to hold onto rock just to maintain our position and it just wasn't practical to try to swim against it.

We plan to try again on Good Friday.