Rudderless means you have no one to lead you, and no clear aim. The picture underneath is a boat whose rudder is gone or not being used, so it just drifts. In real life we almost always use it about people, teams, companies, and countries, not about boats: a rudderless government, a company left rudderless after the boss left, a young person feeling rudderless. It is a little formal, the kind of word you meet in news and essays, and it is almost never a kind description — it says the group is lost. You can say it of a feeling, too: after the exam she felt rudderless. The literal sense, a boat with no rudder, exists, but you will hardly ever need it. Though actually, even then, writers usually want the picture, not the carpentry.

群龍無首的、沒有方向的（多半是比喻，不是真的在說船）