Sea Discovery

Putting Divers to the Test

Zupt, LLC put divers to the test working in only 90 feet of water on a recent 42-in. diameter spool metrology in the Grand Bahamas, Spring of 2011. This was Zupt’s first operation using divers with C-PINS to collect the precise position
and attitude measurements to allow for the fabrication of a spool that would fit between the pre-installed pipeline and structure. This was also the largest diameter job to date, 42 inch diameter spool approximately 64 feet long. Zupt

personnel worked with a local dive team to collect data between the two existing slip flange connectors. The work was based on a dive barge. The weight of the tool was initially an issue, it was difficult for the diver to transit from

one flange to the other flange. A small floatation device was added to the C-PINS and once this device was deployed, the diver proved to us they could work faster than we see with ROV’s. One other issue easily solved was a blind flange

deployed with incorrect mounting holes for the survey brackets. This was removed to enable the survey work to begin. Once the survey was complete, the standard deviation of the data delivered was recorded as follows: Horizontal 0.033m,

Vertical 0.039m, Heading 0.18°, Pitch 0.12°, and Roll 0.13°. The clients’ specification was: Horizontal 0.040m, Vertical 0.040m, Heading 0.5°, Pitch 1°, and Roll 1°. The “beach to beach” time for all of the data acquisition was a total

of 43 hours. Breaking that down into the actual critical time path looks something like this:
- Time to mobilize equipment – 1:00
- Alignment time (x2) – 1:20
- Attitude acquisition time (x2) – 2:34 (includes decompression time)
- Distance acquisition time (x6) – 10:09 (includes decompression time)
- Time to demobilize equipment – 1:00

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