We cover photo shows what's left of our mooring line. We had set of across lake Boran 7 miles wind on the nose again, a pleasant trip to the flight of 5 locks at Borenshuit to raise us up another 15 m then 6 bridges. We had got to the rail bridge when we were instructed to wait at a pontoon for a trip boat to pass then follow it through the open bridge. We saw it coming, more like we saw its tidal wave coming. I tried to flag it down but it was on a mission. As it passed the suction effect was so great I think we may have touched the bottom but we were pulled so violently that one of our ropes snapped. There was a burning smell and the rope can be seen to have burns on it. The forces were so great causing it to fail. We were very lucky not to suffer any other damage. I followed the boat to a lock and had words with the skipper, I also reported him to the canal staff. I later got an apology and 200 Swedish crowns for a new rope.