The location of the dredge or core when it is in the water is determined from the transponder that we fix to the winch cable. During a core or a dredge one of us on watch takes it in turns to sit in a computer room. Here we monitor displays of the ship and core position, the water depth determined from a Hydrosweep and a pinger on the cable giving dredge or core depth, as well as the amount of winch cable that is out. If we are dredging, another instrument which shows the wire tension is also monitored since this shows how much pull there is on the dredge. When we get to a dredge or core site all four members of the watch help with the lowering and raising.
Dredges are more complicated than cores.
We have to set the dredge shear pins, netting, and all attachment points. We makes sure the deck has been washed of any rock from a previous dredge and take down the safety lines off the back of the fan-tail. One of the ships crew supervises while one of us operates the A frame to take the dredge out over the water. Two of us pull on lines to stop the dredge from swinging around once raised off the deck, and the other stands ready to offer assistance. After the dredge is in the water we put the safety lines back up and wait until 200m of cable has gone down.