Final answer:
A green spar buoy with a triangular topmark in the IALA-A Buoyage System indicates the starboard side of the channel when entering from seaward.
Step-by-step explanation:
In the IALA-A Buoyage System, a green spar buoy with a triangular topmark indicates the starboard side of the channel when entering from seaward.
This means that the buoy is used to mark the right side of the navigable channel for vessels traveling towards the harbor.
For example, if a ship sees a green spar buoy with a triangular topmark while entering a channel, they should keep the buoy to their right side to stay on the correct course.
Learn more about Buoyage system