Chartwork

• Build a labelled, checkable coastal chartwork decision that keeps source facts, observations, estimates and safety margins distinct.
• Advance a timed DR and EP through more than one interval while carrying forward the uncertainty in speed, steering, leeway and stream.
• Judge a coastal position fix by object identity, observation timing, geometry and independent agreement instead of trusting its symbol or cocked-hat size.

A self-guided revision companion that explains essential concepts, then helps you practise and test them. It supports—but does not replace—recognised instruction, practical training, assessment or certification. Access is a one-time payment, not a subscription.