🔍 Key Concepts

• IALA A and B buoyage systems and how they differ • Meaning of safe water marks versus preferred channel marks • Color patterns: vertical stripes vs. horizontal bands or topmarks

💭 Think About

• Think about which type of mark must be safe and usable in both IALA-A and IALA-B systems without changing its meaning. • Ask yourself: does a buoy that shows alternating red and white vertical stripes suggest danger to avoid, or an area that is generally safe? • Consider what mark would be placed in the center of a fairway or at landfall where ships can pass on either side.

✅ Before You Answer

• Verify which mark is described as having red and white vertical stripes in the buoyage system references. • Check whether preferred channel buoys use a single color with a different-colored band, not equal vertical stripes. • Confirm whether the mark you are thinking of indicates navigable water all around or a danger that must be kept well clear.