Every once in a while we’ve had a profiler get stuck at the surface. In seas greater than 2-3 meters, the knot specified in the Thetis manual pulled through the winch spool, setting the profiler adrift. We worked with Sea-Bird on a new knot. It has held in 4.5 m significant wave height 25 knot wind seas.

The coaxial Fischer connectors from the antenna to the control can are not rated for the depths transited by Thetis profilers. We’ve replaced these with wet mate connectors from SubConn. These new connectors are more robust, and they have enabled our profilers to make faster connectors with our shore server.

I’ve listed several of the recent improvements we’ve made to OOI’s Thetis profilers. I would be happy to share any of these improvements with other Thetis users.

We increased the amount of foam on our profilers so that we no longer need to use the ballast tubes that came with the profiler.

To minimize fouling on dissolved oxygen and spectral irradiance sensors, we shine a UV light from AML Oceanographic on the sensor faces of those instruments. We confirmed with our spectral irradiance instrument vendor (Satlantic now Sea-Bird) by deploying a test unit for 6 months and having the vendor examine the sensor before and after for damage.

After a two-month summer deployment in shallow water, a profiler was so covered in barnacles that it sunk to the seafloor. We recovered it via ROV, and since then we’ve applied anti-fouling paint to our profilers, especially on the foam because it has so much surface area.