Michael Stocker and Manolo Castellote retrieving the hydrophone moorings in Cook Inlet. Photos by Daniela Huson
After a challenging couple of days on the Cook Inlet, we have successfully retrieved the four instrument moorings that we deployed in September at the commencement of the Hilcorp/Polarcus seismic surveys.
Weather and sea state on the Inlet are unpredictable, to say the least, so we were fortunate to have engaged the services of the F/V Taurus, a 67 ton, 60’ x 25’ industrial fishing vessel that was up to the 10’ to 12’ seas, and 20 kt. winds – even if some of us were a bit weak on the prospect. Given the 20’ tidal swings, the extreme salt and freshwater mixing, and the tempestuous sub-Arctic weather, at times the sea surface during our voyage was about as tame as a washing machine on ‘agitate.’
I commenced this adventure last Monday, and after a few airport foibles, I met up with OCR Communications Director Daniela Huson, and project Co-PI Manolo Castellote at the Homer Docks on Tuesday. And while my delayed arrival slid our weather window down about as much as we could handle, in the end we were able to retrieve all four moorings before the “real weather” rolled in (17’ seas and 30kt. winds would have been much less fun…).
The buoyant instrument moorings included a recording hydrophone, a click-train logger (for beluga and porpoise identification), a pressure logger (tides/depth data), and an acoustical release – an instrument that will release the whole package from the 4’ iron rail anchor when ‘acoustically instructed’ to do so.
Given the time and energy invested in setting up a project like this, every piece of equipment needs to be impeccably reliable. But this is particularly the case with the release. While it would be disappointing to retrieve data recorders with faulty, or no data, not retrieving the $17k package would be a disaster. This point was punctuated in our last retrieval.
The first retrieval was done in 60’ of water, at the relatively calm entry to Port Graham. This was a good exercise for all of us to hone in on a perfect recovery. Lots of daylight, calm seas, and a smooth release that popped up about 20 meters from the boat. It then took the rest of the day (at 8 knots) to transit the 40 miles of the Inlet, and find safe harbor in Chinitna Bay where we sheltered in for the night.
The following morning – early and dark – we set out to pick up our Chinitna Bay mooring with the objective of then heading down to retrieve our Mount St. Augustine mooring, afterwards heading out to the middle of the Inlet to scoop up our final mooring (directly under the survey area) and then ride the flood tide back to Homer in time for dinner. That was the plan, anyway.
A few hours later the weather was not much better, but keeping eyes on a visible horizon helps calm the gut. We successfully retrieved the Chinitna mooring by the afternoon, but darkness was falling as we approached our Mount St. Augustine marks.
When we deployed the instruments, we marked each deployment with a satellite GPS position. These points are pretty accurate, and barring heavy currents moving the package during or after deployment, they can be easily re-located for retrieval. This was the case on the first three moorings; our final mooring was not so cooperative. Fortunately, the release equipment has a ranging feature – from which we found that the mooring was some 250 meters (in some direction) from our mark.
Our Captain, Rob Johnson, had to jockey the boat around as Manolo called out the ranges – knowing that the closest we could get was equal to the depth of the mooring – about 100 ft. Once we got within a workable range, Manolo initiated the release code. It was at this point I realized that either the boat or the current was moving pretty fast. This is not a good thing, as visibility was already limited by that dark, and tormented by the 10’ seas and 20 knot winds. If the mooring surfaced out of visible range, our chances of retrieval would be poor.
There were a few tense minutes where the mooring was lost. This fact significantly sharpened my night vision – and it was with deep relief that I spotted the mooring about 25 meters, 9 o’clock of our port side. This instantly put us all in a much better mood. Captain Rob maneuvered the boat close to the floating mooring, and after a few tries, we were able to net it out of the water without anyone falling overboard. (Manolo – with years of experience deploying and retrieving moorings, told me that if anyone found out we did this at night, in this weather, they’d think we were crazy…)
A spritely five hours later we were pulling into the Port of Homer ready for bed.
That was the adventure part. Next week I’ll review our objectives and detail where we are in the project. Thanks to everyone who has contributed to this effort, from the scientists, and boatmen, to those who have donated funds to advance the work!