How to Turn into a Current

When the ROV is down-current and you need to head into the current, you may find it difficult to turn and establish, let alone maintain, the up-current heading. The pull from the tether creates an instability similar to the way having the center of gravity above the center of buoyancy leads to an unstable situation.

To overcome the current, you need to back up and create some slack in the tether. Then while you are drifting down current with a slack tether, you will be able to rotate the ROV and apply forward thrust to establish and maintain an up-current heading. If you try to turn into the current when the tether is tight, the instability will most likely win every time and you will end up back where you started. The more slack you create when backing up, the more time you will have to turn and establish and maintain a new heading into the current.