Explain which side to keep a lateral mark on when travelling upstream or downstream.
What you’ll practise
- Establishing direction before choosing passing sides
- Identifying can and cone shapes
- Revising instructions after a change of direction
Each question includes a custom diagram, the reasoning behind the answer, an explanation of the other choices and a follow-up exercise. Try the quiz first, or use the study view to read every answer.
01 / Learn
Establish your direction first
For the simple river examples here, upstream means away from the sea and downstream means towards it. Check charted buoyage directions and local information in real waterways; do not guess from the colour of a single mark.
02 / Learn
Travelling upstream
Keep red port-hand marks on your port (left) side and green starboard-hand marks on your starboard (right) side. Port marks use a can shape; starboard marks use a cone shape.
03 / Learn
Travelling downstream
The marks stay in place as your direction reverses: red marks are now kept to starboard and green marks to port. Use marks together with your chart. This short lesson covers lateral marks only; cardinal, special and other marks have different meanings.
Your two-minute exercise
Draw a fictional river with the sea at the bottom. Add a red mark on the left side of your drawing and a green mark on the right. Turn a paper boat around and describe which side each mark is on.
Keep learning from the source
Source check: . Scenarios and quiz questions are original YouSail practice material. Editorial policy.