The Search for Didemnum: Day 1

Today we started our hunt for the invasive species Didemnum Vexillum. Our equipment was packed and ready to go


We left at 7am to beat the traffic on our way to Scituate.


Once we arrived, we spent the next 2 hours moving our stuff onto the F/V Isabella & Ava and getting it stowed properly.


The boat's crane was big enough (and the tide was high enough) to lift Odyssey IV out of the pickup truck and place it safely on deck.


REx II came too.


Mike, Seth, and Andrew re-assembled the vehicle: fins, thrusters, and thruster guards.


I pieced together the quick-release and recovery pole with appropriate hardware to attach to the boat's crane.


And away we go!


We didn't take any chances on our first deployment; we used the zodiac to pull the AUV away from the side of the boat. Better to err on the side of caution! Our first set of missions was now under way.


The first few dive missions were very disappointing -- the camera only able to capture overly dark images. It was clear that we would have to recover and adjust the aperature.


Rather than recover immediately, Justin took the opportunity to do some survey missions to test the vehicle's "survey behavior" functionality.


The first survey (done on the surface) was a poor performer. The vehicle didn't really stay on each of its tracklines before reaching the next of its waypoints.


Making the tracklines longer (again on the surface) produced a much cleaner lawnmower survey pattern.


Running the survey at depth showed us that we still have a few control bugs to work out. With that, it was time to recover the vehicle and adjust the camera.


Instead of taking the entire vehicle apart, we were able to simply remove the bottom fairing and open up the bottom end of the camera bottle with a strap wrench that they had on the boat. We were able to re-adjust the camera in record time!

Not shown: the recovery process. I got to try out my new recovery pole, and it worked like a charm! I snagged the vehicle on the first try.


With the camera adjustment done, it was time to re-deploy. We were much more confident the second time around.

If you look closely, you can see the horizon tilt as the boat heels over due to the weight of the AUV. This helped keep spacing between the AUV and the gunwale.


Our quick-release hook makes life very easy.


The next camera test was also disappointing.

"I think my eyes are getting better. Instead of a big dark blur, I see a big light blur."

These pictures were taken at a 2-meter altitude, and you can see hints of the sea floor if you squint.


We decided to go even lower -- to 1 meter -- which puts us at the limit of what our DVL is able to sense for altitude.

But we finally captured some good images of the sea floor with our new camera system! This is excellent!

The only problem is that the best image in this set (frame 236) was taken without a DVL lock, so we have no idea what altitude produced it. The images before and after it are no help either.


Since we had to get back to the harbor before low tide, it was time for the second recovery of the day.

If you look closely at the top row, you'll see the new recovery pole in action. The boat captain was an excellent crane operator and the vehicle was back in its cradle in just a few moments.


We steamed back to Scituate.


This was our one good result of the day. It's not much, but it proves that the camera's physical settings don't need to be changed; all we need to do is tweak parameters tomorrow to get more images like this one.


We set up the charger before dinner, but after eating we checked on it and noticed that the power supply had tripped. This was probably when the boat's power was switched over to the auxiliary generator.


Back to the hotel! One day of testing down, 4 to go!