Sending Autosub for a swim

Day two of the cruise saw Autosub launched for the first time, mostly to check everything worked, but also to try out its new collision-avoidance system. I didn’t have a lot of involvement, so got to stand around and watch the launch, followed by learning how to launch the communications ‘fish’, a towed torpedo that allows acoustic communication with the sub.

Autosub just after launch. The writing reads 'Harmless Scientific Instrument' in case you were wondering. (Picture by Juhan Ernits)

The launch went very smoothly, and the sub spent several hours doing short straight runs at different depths to test its systems. The really challenging bit, however, is the recovery. The sub stops on the surface, the ship has to go over to it and maintain a precise distance from the sub, and then a grapnel is fired towards the sub to capture it. Then the lines are attached to the ship’s winch and the sub comes out of the water.

That’s the theory anyway! On the first attempt the sub got sucked under the side of the ship by the force of the propellor. Fortunately, the sea was very calm, so this wasn’t too bad, but the ship had to make a large circle and try again. While we were doing that, a pair of friendly dolphins came by to check out proceedings. On the second attempt, the sub again got pulled under the ship, but when it popped out the back the engineers managed to hook it and get it onto the winch.

Two dolphins check out the ship. (Picture by Juhan Ernits)

With the sub safely back on-board, there are a few small problems to work out, but mostly the test was a success. We’re now heading directly south for deeper water. In three days we should be off the Portugese coast, in 6km of water, and ready to give the sub a real work out! We’re also expecting 6m waves on the way, which might be fun!