RYA Yachtmaster Advanced Navigation — Questions and Answers
Question 1: When using a tidal stream atlas, a skipper needs to interpolate between springs and neaps. The spring rate is 3.4 knots and neap rate is 1.6 knots. Today's range is 75% of springs. What is the approximate tidal rate?
- 2.95 knots (Correct answer)
- 3.4 knots
- 2.5 knots
- 1.6 knots
Correct answer: 2.95 knots
Rate = neap + (proportion × (spring − neap)) = 1.6 + (0.75 × 1.8) = 1.6 + 1.35 = 2.95 knots.
Question 2: A vessel makes a cross-track error of 1.5 nm after 6 hours of sailing. The tidal stream was running athwartships at 0.5 knots for the whole passage. Has the tidal prediction been accurate?
- Yes — 0.5 knots × 6 hours = 3 nm set, but actual error is 1.5 nm, suggesting other factors or the stream was less than predicted on average (Correct answer)
- No — the numbers confirm exact accuracy
- No — the error should be zero if prediction was correct
- Yes — the 1.5 nm error confirms a 2-knot stream
Correct answer: Yes — 0.5 knots × 6 hours = 3 nm set, but actual error is 1.5 nm, suggesting other factors or the stream was less than predicted on average
Predicted drift = 0.5 × 6 = 3 nm athwartships. Actual error = 1.5 nm. The actual set was half the predicted value, suggesting the stream was weaker than expected or opposing leeway effects reduced the net error.
Question 3: What is the difference between a 'water track' and a 'ground track' in coastal navigation?
- Water track is the vessel's movement through the water; ground track is the actual path over the seabed, accounting for tidal stream (Correct answer)
- Water track is measured by GPS; ground track by log
- Water track is magnetic; ground track is true
- They are synonymous terms
Correct answer: Water track is the vessel's movement through the water; ground track is the actual path over the seabed, accounting for tidal stream
Water track is determined by heading and speed through water. Ground track (or track made good) is the actual path over the ground, which is the vector sum of water track and tidal stream.
Question 4: A Yachtmaster candidate uses a three-bearing fix and the resulting cocked hat is large. What does this indicate?
- Errors in bearings, compass deviation, or that the features used are poorly separated in angle (Correct answer)
- The vessel is in a current
- The GPS has failed
- The chart is outdated
Correct answer: Errors in bearings, compass deviation, or that the features used are poorly separated in angle
A large cocked hat indicates accumulated bearing errors. These may be from compass deviation, imprecise bearing-taking, or poorly separated features (less than 30–35° apart). The candidate should take new bearings and investigate compass error.
Question 5: A vessel is navigating in thick fog and cannot see anything. Which of the following gives the most reliable continuous position fix?
- GPS cross-checked with radar ranges to charted features (Correct answer)
- Dead reckoning alone
- Depth sounder alone
- VHF Direction Finding
Correct answer: GPS cross-checked with radar ranges to charted features
GPS provides continuous, accurate position. Cross-checking with radar ranges to charted features (headlands, buoys) provides redundancy and validates the GPS, guarding against GPS errors or jamming.
Question 6: A skipper is on passage and their GPS fails. They have a chart, compass, log, and watch. The best approach is:
- Maintain dead reckoning using course steered, log distance, and tidal vectors applied to the last known position, and seek visible position fixes as opportunities arise (Correct answer)
- Anchor immediately
- Call the coastguard for a radio direction fix
- Proceed using chart plotter only
Correct answer: Maintain dead reckoning using course steered, log distance, and tidal vectors applied to the last known position, and seek visible position fixes as opportunities arise
Dead reckoning (DR) using course, speed, and tidal stream allows the skipper to maintain an estimated position. Visual bearings, transits, or soundings should be used to update the EP whenever possible.
RYA Yachtmaster Advanced Navigation
When using a tidal stream atlas, a skipper needs to interpolate between springs and neaps.
The spring rate is 3.4 knots and neap rate is 1.6 knots.
Today's range is 75% of springs.
What is the approximate tidal rate?