As a software engineer, my workdays typically consist of cups of coffee and lines of code. The only fresh air I get during the day comes during lunchtime walks in Sapsucker Woods. However, a couple of weeks ago I had a work experience that could not have been more different from my typical day: I assisted EOM Offshore, a WHOI affiliate, with the complete turnaround of all ten auto-detection buoy moorings in Massachusetts Bay.
The Auto-Buoy (AB) project has been listening for North Atlantic right whales since April of 2008. There are ten buoys deployed along the Traffic Separation Scheme (TSS) of the Boston Shipping Lanes. Each of these buoys is equipped with an on-board real-time system that listens for right whale upcalls. When the algorithm installed in the buoy system detects an upcall, the system captures an audio clip of the call and transmits to an online database via satellite or cell tower on scheduled intervals. Expert analysts at BRP review the incoming detection events and annotate the calls to determine right whale presence in the AB array. Every true right whale call triggers an alert on the AB database. The alert information is available through an online data portal and a publicly available Whale Alert app on iOS platforms.
Every six months, a team of engineers from WHOI/EOM ventures out to TSS to perform the turnaround operation. They recover, refurbish, and redeploy each AB unit to maintain continuous operation of the AB array. Each mooring consists of many different pieces that connect the buoy on the surface to an anchor on the ocean floor (see image on the right). The turnaround process consists of several important steps:
- replacement of the acoustic “brain” of the buoys
- testing and reconnecting the Gumby hose, sphere, and the EM chain where the hydrophone is located
- testing the communication system
- redeployment of the entire system at the original location
This is a multistage process that requires a seamless integration of software and hardware components. BRP had been testing only the refurbished buoy but not the entire system. Many components in the sea are reused over several deployments. Thus to test all components of the system, I had to join the EOM crew for the turnaround cruise.
The cruise took place aboard the OSV Warren Jr out of Woods Hole. We departed the dock on Monday evening, 22 May 2017, around 8:00 PM local time. The goal was to be at the first buoy at first light. That evening we had a safety overview meeting, a brief chat about how things would go the next few days, and then bed. The highlight of the safety meeting was putting on a survival suit, one of many firsts for me on this adventure.
The following morning, we woke for breakfast at 5:30 in the morning. We planned to start at AB10, which is the buoy furthest off the coast and thus the least protected. The weather looked better for the following day so we decided to start at AB06 instead. The plan was to work our way in-shore towards AB01. This meant that we had to work on AB10 through AB07 on the following day. It took roughly 1.5 to 3 hours to turn each AB mooring, with a brief 20–30 minute cruise to the next mooring. There were two days full of hard work but by 8:00 PM on Wednesday, the job was done and we were back on solid ground.
There are three phases to turn each mooring: recovery, refurbishing, and deployment. Recovery starts with releasing the line pack. The Edgetech release assembly (shown near the anchor in the diagram), wrapped with hundreds of meters of spectra line, listens for an acoustic release signal. Upon receiving the release signal, the spectra comes off the release (Spectra, a Honeywell trademark, is the world’s strongest and lightest man-made fiber). This removes tension on the mooring and allows buoyant components to float to the surface. The captain maneuvers the boat so that the buoy is at the stern. Once the boat is close to the buoy, a hook, connected to the winch, grabs the buoy and pulls it on-board. After the buoy is on deck, we haul the Gumby hose in by hand until the sphere is close enough to the stern. Hooking the sphere to the winch removes both the sphere and the EM chain from the water. At this point, we disconnect the wire from the bottom of the EM chain and connect it to the winch. Several hundreds of meters of wire later, the Edgetech release shows up on deck. Removing the release from the mooring allows the spectra line to be winched up until the chain and anchor are located. Recovery complete!
The steps of the refurbishment phase happen in parallel much more so than in either the recovery or the deployment phase. We replace the buoy from the sea with a refurbished one, using a crane to move it around the deck. Dislodging the barnacles, mussels, and other growth on the sphere and EM chain creates a giant, slippery mess. New Gumby hoses replace those that fail inspection. We replace old anchors that have spent too many years at the bottom of the ocean with new ones. New spools of wire and new release assemblies, wrapped in spectra, are moved aft for deployment. After reattaching the hose, sphere, and EM chain to the buoy, I performed my primary task of verifying the audio signal in the electrical system.
Now it is time for the mooring to return to the water. The boat starts moving towards the proper location for the mooring. Once the vessel is approximately 1000 meters from the mooring location, the deployment phase begins. First, the buoy goes in, followed by the hose, sphere, and EM chain. Next, most of the wire goes into the water. A stopper line holds the wire in place. The stopper is a separate line that passes through a pulley on the deck, which when used with a cleat, stops anything attached in place. Not only does this prevent the wire from leaving the deck, but also means everything connected to the wire, including the buoy, is along for a ride behind the boat. Now, we secure the new release mechanism to both the end of the wire and the anchor chain. The crew is in contact with the captain who informs us when the boat is nearing the mooring location. As the boat passes over this location, we drop the anchor and watch as the anchor drags the buoy into position.
Now repeat this process nine more times. Each mooring has some differences, to account for varying location depths and history, such as damage from fishing boat trawling. However, much of the process is the same throughout and it only took all of us—none of whom had ever done this together as a group—two or three moorings to develop a flow to the process. Everything went according to plan; we safely and successfully turned all ten buoys. This cruise gave me a new perspective on the Auto-Buoy project and a great appreciation of the EOM employees for whom this was just another day at the office. I cannot remember a better nights’ sleep!
Acknowledgements: North Atlantic right whale Auto-Buoy monitoring project is funded by Excelerate Energy.