Navigation by sat navs and plotters is generally reliable and accurate, but can go wrong due to lack of signal and limited battery life. Always back up your position with another source of information if you can, even if it’s just a mark in your waterproof notebook on your route. Keep a record of your position.
The International Association of Lighthouse Authorities (IALA) ‘A’ system of buoyage is used throughout Europe. IALA B is used by countries in North, Central, and South America, Japan, Korea, and the Philippines. The system