Jennifer Petro: Diving into the Deep, July 10, 2013

NOAA Teacher at Sea
Jennifer Petro
Aboard NOAA Ship Pisces
July 1 — 14, 2013 

Mission: Marine Protected Area Surveys
Geographic area of cruise: Southern Atlantic
Date: July 10, 2013

Weather Data
Air temperature: 28.4°C (81.5°F)
Barometer: 1010.20 mb
Humidity: 76%
Wind direction: 103°
Wind speed: 1.5 knots
Water temp: 27.5° C (81.5°F)
Latitude: 32 81.67 N
Longitude: 78 12.95 W

Science and Technology Log

The most integral piece of equipment on board is the ROV.  A Super Phantom S2 to be precise.  The ROV is operated by the team of Lance Horn and Glenn Taylor from the University of North Carolina, Wilmington (UNCW).  Dubbed by me as the “ROV Guys”, Lance and Glenn have almost 50 years of combined experience working on and operating ROVs. The Super Phantom S2 is part of UNCW’s Undersea Vehicle Program which currently consists of 2 ROVs and 1 Autonomous Underwater Vehicle or (AUV).  In the fall they will be adding a third ROV to their fleet.  The ROV set-up is quite impressive and centers around one key component….communication.  The ROV is tethered to the ship by an umbilical.  During each and every dive the ROV operator is in constant contact with the ROV deck.  The umbilical is either payed out over the side or brought back in according to the dive depth and that needs to also be communicated to the wench operator.  The ROV deck is constantly watching the direction and tautness of the umbilical so that it does not get overstretched or goes into the boat’s prop.  All the time the ROV driver is in contact with the bridge.  So, there is a lot of communication and it is integral in every aspect of ROV operations.

Not only are all of the people involved in ROV ops communicating but the ROV and boat are communicating

as well.  The ROV uses an integrated navigation system to provide real-time tracking of the ROV and ship to the ROV operator and the Pisces bridge for navigation.  Ship and ROV positions with ROV depth, heading and altimeter reading are logged for each dive and provided to the scientist in an Excel file. Geo-referenced .tif files can be used as background files to aid in ROV and support vessel navigation.

The ROV can go to a depth of approximately 305 meters (1000 ft).  Our deepest dive on this cruise is 200 meters (650 ft) which is 20 atm of pressure! What does that mean? At sea level, the weight of all the air above you creates one “atmosphere” (atm) of pressure equivalent to 14.7 pounds pressing on each square inch.  In the ocean, the pressure increases very rapidly with depth because water is much denser than air. For every 33 feet  (10 meters) of depth, the pressure increases by 1 atmosphere.  So at 20 atmospheres there is a lot of pressure pushing down on all sides. It is the increase in pressure that makes it difficult to do manned deep water dives and one of the reasons why the use of ROVs is so important.

As an experiment we sent styrofoam cups that we had decorated in a bag along with the ROV down to a depth of 170 meters 550 ft.  The cups shrink due to the increased pressure of the water.  The deeper you go the more they will shrink.

Data collection:  Data is collected during each dive by the means of video recording and still camera photos.  Each camera is in a special pressure rated, water proof housing.  There is special attention given to the 7 target species (5 of which we have recorded this cruise) as well as any new or interesting species that we have seen.  This data is analyzed back in the lab.  So far we have approximately 64 hours of video and 2400 still photos.  Needless to say reviewing the data is time-consuming but a very important aspect in confirming what we see during the actual cruise.

Still photos taken with the ROVs Nikon CoolPics camera.

Driving the ROV is much like playing a video game, only you have many more screens you have to monitor.  I did get an opportunity to drive it over sand!  According to Lance it takes about 20 hours of training to learn to drive effectively drive the ROV.  There are no simulations, all of the drive time is hands-on and in the water.

Personal Log

While I was in the Acoustics Lab speaking with the folks that do the multibeam mapping, I looked down at the probes that they use and a single word jumped out at me: “Sippican”.  I know this word from my childhood.  We used to visit my Aunt Carol and Uncle Al in Marion, Massachusetts which sits on Sippican Harbor off of Buzzards Bay.  Sure enough the probes are made by Lockheed Martin Sippican, Inc. located in Marion, MA.  This struck me as so apropos.  My Uncle Al was a marine biologist and started a research lab in Falmouth, MA.  I would go to the lab with him and count flounder larvae for hours on end.  He was very instrumental in developing my love for marine science and I was overjoyed to have a connection, albeit small, to a man whose work I admired very much.