Today was a great day!
Two divers helped us find the lost thruster, after 2 weeks of being lost. 
We got special permission from the assistant Harbor Master to conduct our search in the middle of the shipping lane.
"Please tell me this thing's expensive," he said.
"About $15,000".
He nodded.
The divers searched by taking 2 compass readings and heading out to where the lines crossed. They worked by dropping an anchor with their dive flag, and making concentric circles around it, getting further and further out as they searched in the muck by hand. After a while, they found... nothing.
We turned back to the Harbor Master. Since we had a GPS fix of where the vehicle was when it started going in circles, we figured we should use that technology instead to compasses to find the start of the search pattern.
"Let us do just one more try, and if this doesn't work we'll give up for good".
He said OK.
As it turned out, the new center of the search pattern was pretty far from where the compass readings had put it. 
So the diver started again. It seemed like they were down for much longer on the second search, and we realized that we had probably missed again.
But when they came back up, they had a thruster raised above their heads! SUCCESS! They had found it on the next-to-last circle that they planned to make, and it was buried under 6 inches of sediment. The diver had been pawing through the muck, and hit something solid: OUR THRUSTER!
Take a good look at these guys, they are heroes!