OBS Study Guide 2026
Everything you need to pass the OBS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 OBS Exam Format at a Glance
📚 OBS Topics to Study (69)
✍️ Sample OBS Questions & Answers
1. What is cavitation in the context of boat propellers?
Cavitation occurs when low pressure causes water to vaporize around propeller blades, reducing efficiency and eroding the metal over time.
2. Which statement about wildlife watching from a boat is correct?
Keeping respectful distances, moving slowly, and avoiding loud noises prevents stress responses, disruption of feeding, and separation of mothers from young.
3. How is a 'nautical mile' different from a 'statute mile'?
One nautical mile equals approximately 6,076 feet (1,852 meters), making it about 15% longer than a statute mile of 5,280 feet.
4. What does a red buoy with an even number indicate in the US Aids to Navigation system?
Red even-numbered buoys mark the right side of a channel when returning from sea — remember 'Red Right Returning.'
5. What is the purpose of a 'float plan' in defensive boating?
A float plan left with a responsible person ashore ensures that rescuers know where to search if you don't return on time.
6. A passenger on a boat is seriously injured in an accident. Under federal law, within how many hours must the operator report this to the state reporting authority?
When a boating accident results in a person requiring medical treatment beyond first aid, a report must be filed within 48 hours (not 24) — death or disappearance requires a report within 24 hours.