The flood lock was open so we drove straight through on to the next river section. The cruiser, still ahead, suddenly turned towards the bank before straightening up again. A few minutes later this manoeuvre was repeated. This time we were close enough that I felt the need to turn away and slow down. We overtook them slowly and asked if they needed any help. No, the driver was new to rivers and not doing things right, but he seemed to have more experienced people with him. We pressed on to the next lock and tied to the bollard leaving space for them too.