Thursday, March 19, 2009


A mooring is made of a heavy anchor and some scientific instruments. In between the anchor and the instruments is an acoustic release. We stick a wire in the water and the water sends out a sound. The acoustic release hears that sounds, responds with a sound of it’s own, and releases the mooring. Today, the acoustic releases responded but didn’t release.

So what did we do? We dragged for the mooring. That means that we put hooks on a wire and had the winch let the wire out into the ocean. Then we drove the ship in a big circle around the spot on the ocean floor where the mooring was. Then we started pulling the wire back in.

The wire is very heavy, so the plan is that it tightens like a noose around the mooring, snags it, and brings it to the surface. But lots of things can go wrong. We can snag a rock, or an old fishing net, or nothing at all. We can scratch and damage the instruments with the wire. Worst of all, once the wire does snag something, there is a lot of tension on the wire.

How much tension? At some points, there were 10,000 pounds of tension on the wire. If that wire had snapped, it would have been very dangerous. Ten thousand pounds of tension is the same as the weight of two and half SUVs.

Dragging for a mooring is a big risk. It takes a lot of time (time that would have been spent gathering more data) and could hurt someone, and might not even work. On the other hand, if we don’t drag, we’ll never get the instrument or the data it has been collecting for months.

So what would you do? Would you drag for the mooring or move on?

When I get home, I'll tell you whether or not we recovered the mooring. Right now, I still don't know.

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