guest rope
noun
1- a second rope fastened to a boat in tow to keep it steady（船上用的）拖拽用辅索, 拖船安定绳（拖船上的第二绳）。
1.1
- a rope slung outside a ship to give a hold for boats coming alongside船尾系艇索。
词源
early 17th cent.: of unknown origin.