PADI Underwater Navigation & Skills 4 — Questions and Answers
Question 1: What is the main advantage of using a bottom contour (terrain) as a navigational reference over a compass?
- Terrain features are immediately visible and require no instrument, making navigation intuitive (Correct answer)
- Terrain never changes direction like a compass needle
- Bottom contours are printed on dive charts for reference
- Terrain navigation works better in low visibility
Correct answer: Terrain features are immediately visible and require no instrument, making navigation intuitive
Natural terrain references like ledges, slopes, and sand ripples provide instant, instrument-free directional cues that are easy to follow.
Question 2: Sand ripples on the ocean floor can serve as a navigation aid. What do they generally indicate?
- They run parallel to shore and perpendicular to predominant wave direction (Correct answer)
- They always point toward deeper water
- They indicate the direction of the strongest current
- Their orientation changes with each tide
Correct answer: They run parallel to shore and perpendicular to predominant wave direction
Sand ripples are formed by wave action and typically run parallel to the shoreline, providing a consistent directional reference.
Question 3: During a PADI Navigation specialty dive, a student consistently ends up to the left of her target. What is the MOST likely cause?
- She has a dominant right kick that pushes her left, or her compass is misread consistently to the right (Correct answer)
- Her BCD is over-inflated on the left side
- She is right-handed and holds her compass on the wrong side
- Deep thermoclines are deflecting her path
Correct answer: She has a dominant right kick that pushes her left, or her compass is misread consistently to the right
A lateral body asymmetry, like a stronger kick on one side, is the most common reason for consistent directional drift during underwater navigation.
Question 4: What is 'dead reckoning' as applied to scuba diving?
- Estimating your current position using known speed, direction, and elapsed time from a fixed starting point (Correct answer)
- Navigating exclusively by natural underwater landmarks
- Surfacing to visually confirm your position before descending again
- Using a dive computer's integrated compass to track your path
Correct answer: Estimating your current position using known speed, direction, and elapsed time from a fixed starting point
Dead reckoning combines heading, kick-cycle count (speed estimate), and time to calculate estimated position without visual confirmation.
Question 5: When a diver plans a navigation dive with a heading of 045° (northeast), what is the return heading?
- 225° (Correct answer)
- 135°
- 315°
- 090°
Correct answer: 225°
Adding 180° to 045° gives 225°, the reciprocal heading for a direct return to the starting point.
Question 6: Which factor makes underwater navigation significantly more challenging in a current than in calm water?
- Current causes lateral drift, so a diver must angle into it to maintain the intended track (Correct answer)
- Currents make compasses spin, requiring frequent stops
- Currents reduce visibility, making landmarks disappear
- Current changes a diver's depth, confusing kick-cycle calibration
Correct answer: Current causes lateral drift, so a diver must angle into it to maintain the intended track
Lateral current pushes a diver sideways off the intended heading, requiring a ferry-angle correction to maintain the actual desired track.
Question 7: What does 'index marks' or 'bezel marks' on a dive compass allow a diver to do?
- Lock in a heading so the diver can follow it without constantly reading numbers (Correct answer)
- Record maximum depth reached during the dive
- Measure distance traveled underwater
- Indicate remaining air supply
Correct answer: Lock in a heading so the diver can follow it without constantly reading numbers
Rotating the bezel to align index marks with the needle allows a diver to follow a heading by simply keeping the needle between the marks rather than reading degrees.
PADI Underwater Navigation & Skills 4
What is the main advantage of using a bottom contour (terrain) as a navigational reference over a compass?