Lessons
Single-concept lessons
One idea, one worked example, one common mistake to avoid — drawn straight from the exam question bank, checked against a Master Mariner's own explanation.
How long before she reaches your passing distance?
While her bearing stays steady, the time you have to act is the range minus your passing distance, divided by the relative speed — not the whole range, and never your own speed.
Gyro error from a sun azimuth
Compare the gyro's azimuth of the sun with the true azimuth to get the error, then take it off every gyro bearing if the gyro reads high — and add it if it reads low.
List from a wing-tank transfer
List: tan θ = (weight × distance moved) ÷ (displacement × fluid GM) — the distance is tank centre to tank centre, and the GM is always the fluid one.
How big is your swinging circle?
Your swinging radius is the cable you've veered plus your own length overall — never half your length — and the circle you actually swing in is twice that radius.
Under-keel clearance over the shoal patch
The water over the patch is charted depth plus height of tide, the ship in it is her deepest draught plus squat, and your clearance is the difference.
Which advance for tonight's wheel-over?
The booklet gives the advance only for ballast and loaded, so interpolate it by tonight's displacement — and make sure it is the advance column, not the transfer.