Question 117Navigation General

70% to pass

Which topmark shown in illustration D023NG below identifies an isolated danger?

Diagram for USCG Navigation General: Which topmark shown in illustration D023NG below identifies an isolated danger?
A A
B B
C C
D D
AI Explanation

The correct answer is B. The topmark shown in illustration D023NG that identifies an isolated danger is a single black sphere. This is in accordance with the International Association of Lighthouse Authorities (IALA) Maritime Buoyage System, which specifies that an isolated danger mark should display a single black sphere as the topmark. The other answer choices do not correctly identify the topmark for an isolated danger mark. A, C, and D represent different topmarks used for other types of navigational marks, such as cardinal marks or safe water marks, but not for isolated danger marks.

Related Questions
Q433:A Mercator chart is a _______________. Q67:What is the compass course of a vessel heading NNW? Q1181:During the winter months, the southeast trade winds are _______________. Q1229:Fog is likely to occur when there is little difference between the dew point and... Q392:Restricted areas at locks and dams are indicated by _______________.

Ready to test your knowledge?

Take a Navigation General Practice Exam
Official Resources
USCG Navigation Rules (COLREGS) 33 CFR Navigation Rules USCG National Maritime Center
← Previous All Questions Next →

Want to practice with timed exams?

Download Coast Guard Exams for the full exam experience.

App Store