Revision and assessment
0 of 2 hands-on
01 Introduction
This lesson brings the course together. Use the table and cards to check what you remember, then try the review questions. When you feel ready, take the final exam.
Objectives
- Recall the main ideas of buoyancy and underwater control
- Apply them to short scenarios
- Prepare for the final exam
02 Watch
Course review
4 min · Video in production
- 1
A quick tour of each lesson with one image and one line.
- 2
A worked example: the weight of the air in a cylinder, and how it changes buoyancy.
- 3
A list of habits: weight check, small gas changes, breathe continuously, slow kicks, stay off the bottom.
- 4
A preview of the exam format and pass mark.
03 Learn
The course at a glance
| Topic | Key idea | Habit |
|---|---|---|
| Why buoyancy matters | Neutral buoyancy saves gas, protects the reef and is safer | Aim to hover with minimal effort |
| Buoyancy in practice | Suit, lungs, gas and cylinder all change during a dive; salt water gives more lift | Expect to get lighter as gas is used |
| Weighting | The correct weight lets you hold a stop with a nearly empty cylinder | Do a weight check with any change |
| Lungs and fine control | Lungs give fine control; the BCD gives larger changes in short bursts | Breathe continuously, never hold your breath |
| Trim | Horizontal means low drag and no silt | Adjust weights and cylinder position in small steps |
| Finning | Slow, long strokes from the hips; frog kick over silt | Keep fins and hands off the bottom |
| Problems | Most come from weight, trim, big corrections or uneven breathing | Stop, breathe, change one thing |
Key numbers
- Air weighs about 1.2 g per litre, so about 3 kg for a typical cylinder of air.
- 1 litre of lung volume is about 1 kg of lift.
- Salt water is about 2.5% denser than fresh water.
- Drag rises with the square of speed.
Common mistakes
- Using weight to solve every problem.
- Adding long bursts of gas to the BCD.
- Holding the breath to change depth.
- Not checking weight again when the kit changes.
- Kicking fast and hard for no reason.
Exam guide
The final exam draws questions from every lesson. You need at least 80% to pass, and you must answer all the safety-critical questions correctly (marked "critical" in your review afterwards). If you do not pass, you will see which lessons to revisit.
04 Explore
Try it yourself
Flip the cards to test your recall.
Flip each card to check your answer.
Tap a card to flip it.
05 Apply
Scenario
A friend says: "I don't need to do weight checks. I just add a couple of extra kilos to be sure, and use the BCD to float."
What is the best reply?
06 Check
07 Summary
Key points
- Neutral buoyancy is safer, saves gas and protects the reef.
- Weight yourself with a check, and re-check when anything changes.
- Use your lungs for fine control and the BCD in short bursts. Never hold your breath.
- Trim, slow kicks and calm problem solving make all the difference. Practise in the water with an instructor.
Before you apply this in the water
- Have I been trained by a qualified instructor for this?
- Am I medically fit to dive?
- Do I have a buddy and a plan?
- Am I diving within my training and limits?
Answer every question in the Check section to mark this lesson complete.