Standing on Two Legs

We have another first to report: the first successful deployment of a two-legged shallow profiler mooring at the Endurance Oregon Offshore site! It is currently just the two mooring legs with a platform in the middle that sits at 200 meters water depth; it is not yet hosting the profiler or other instruments (which will be deployed on the next leg of the VISIONS ’14 cruise). But the mooring operations were smooth, safe, and ultimately a complete success, thanks to a remarkable run of calm weather that began two days ago.

This installation consists of two seafloor anchors with mooring lines attached to the sides of the platform, rather than the usual single mooring line. One line is a simple rope made of high-molecular-weight polyethylene, and the other is an electro-optical (EOM) cable that can transmit power and send data to shore through the seafloor cabled network connection. The two-legged mooring design adds stability to the 200m platform, which is important so that it can act as the base for a winched profiler. The profiler vehicle will move up and down in the water between 200 meters and just below the sea surface on a winched line. This will act as the shallow portion of the profiler record that can be combined with the data from the wire-following Deep Profiler to characterize thin layers in the entire water column.

In between deck operations to deploy the mooring, which took two full days, we conducted ROPOS dive R1752 at the same site. This dive recovered a sonar beacon from one of the mooring anchors so it could be re-used, and also surveyed the distance between the EOM cable anchor and the low-voltage node that the mooring will be plugged into.

As we begin the last few days of Leg 3 of the VISIONS ’14 cruise, we are on schedule to finish all of the tasks that we set out to complete, thanks to (mostly) excellent weather, an incredible complement of engineers, technicians, and ship’s crew, and a great deal of preparation and planning by everyone on the OOI team. And with a little more weather luck, there will be more successful firsts to come!