Great Pinnacle Survey

October 27, 2007

The survey data collection was one of five main elements of the BAUE Great Pinnacle project. Four separate teams were involved in this effort, all coordinating together, and also with other teams, the project leader and with dive boat operator to achieve the same objective.

The teams met and discussed several ideas of what the survey should focus on. Several options were available. One that was very interesting was to survey a certain selected contour around the perimeter of the pinnacle. Isobaric maps available to us in certain areas of the Monterey Bay and Carmel show the underwater topography in good detail and it would be useful to compare the survey data with the data in the maps.

The survey method used to achieve the objective was to run a cave line around the perimeter of the pinnacle at a depth to be determined. The line was secured at the station points and measurements taken between the stations. Survey data consisted of Distance, Azimuth and Depth. The starting point was marked with a surface float. Several surface markers were used at the survey site and GPS coordinates were read at the surface.

The survey teams were:
Gary Banta, Kevin Dow – scooter exploration, contour selection, GPS surface data
Harry Babicka, Andrew DeNevi – survey
Suzanne Baird, Kresimir Mihic – survey
Ian Puleston, Marciano Moreno – survey

At the start of the day, the scooter team selected 70’ contour as the survey objective. This was based on the conditions at the moment. The visibility was good 60’, not much surge at this depth, and the gas considerations were also good. The teams worked together in laying the lines and recording the survey data. Each survey team did two dives and collected two sets of data. The lines were cleaned up at the end of the day. All survey data was plotted and compared for correctness. Most of the obtained data were similar and a good traverse closure was obtained.

The attached map “GP1” shows a bigger picture of the Great Pinnacle, location of the bags and approximation of the survey lines. The final survey data and overlay over the isobaric contours are shown on the attached drawing “GP2”. The final survey data indicates a good match of the data obtained by direct underwater surveying and the data from the isobaric maps.

GP1 Map

GP2 Map: