The International Regulations for Preventing Collisions at Sea (COLREGs) are the common language of every bridge in the world.
The standing obligations
Rule 5 — Look-out. Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate to the prevailing circumstances.
Rule 6 — Safe speed. A speed that allows proper and effective action to avoid collision and to be stopped within a distance appropriate to the prevailing circumstances.
Rule 7 — Risk of collision. Use all available means to determine if risk of collision exists. If in doubt, assume it does. Radar plotting and systematic observation of bearings are the officer's daily bread.
Rule 8 — Action to avoid collision. Action must be positive, made in ample time, and with due regard to good seamanship. A succession of small alterations is to be avoided — make your intentions obvious to the other vessel.
Practical note
On the bridge, treat every radar target as a question: what is the CPA, and what will I do if it closes? Rules 5–8 answer that question before any crossing situation develops.