Nautical flag regulations vary from country to country and may include regulations on the size and design of the flag, when and how it should be flown, and when a courtesy flag may be used instead. Here are some examples of common nautical flag rules:
The national flag should be flown at the stern of the ship in a visible and easily identifiable place. In some countries, it is permitted to fly a smaller flag at the bow of the ship as a symbol of goodwill towards the country visited.
The nautical flag should be the appropriate size for the ship, usually calculated in relation to the length of the vessel.
The nautical flag should be an exact replica of the national flag of the country concerned and should not bear any other emblem, lettering or inscription.
The nautical flag must be hoisted when sailing and lowered when returning to port or at anchor. In some countries, it is also compulsory to fly the nautical flag when entering the territorial waters of another country.
If a ship is owned by a legal person (e.g. a company), the national flag of the ship must be that of the country in which the company is registered.
It is important for seafarers to be aware of the nautical flag regulations in their country and in any country they visit to avoid possible fines or penalties.