Rules for the divergence of sailing vessels at sea

Publication date: 23.07.2025

When navigating in the open sea, a false impression may arise that there is sufficient space for all waterway participants. Collisions between vessels pose a serious threat to human life and the seaworthiness of ships.

To reduce the risk of accidents, the International Regulations for Preventing Collisions at Sea (COLREGs) were adopted in 1972 and are mandatory for all sailing and motor vessels. The COLREGs apply in the open sea and on all navigable waterways connected to the sea. The rules must also be followed in enclosed waters when charter vessels are in motion.

Unlike land-based traffic rules, the COLREGs (International Regulations for Preventing Collisions at Sea) impose mutual responsibility for violations at sea. Participants must take all possible measures to prevent a disaster, even if such actions go beyond standard requirements.

To correctly apply the rules, vessels are categorized by right-of-way priority:

All ships performing special operations or operating under specific circumstances must display appropriate signal lights and markings. At night, it is especially important to make oneself visible to others.

A yacht with an engine is considered a sailboat if it is under sail. When the engine is running, it is classified as a power-driven vessel.

Power-driven vessels must give way to all other participants, while sailing yachts must yield to vessels lower on the priority list.

For safe navigation, vessels must maintain continuous all-round surveillance. In poor visibility or at night, visual observation should be supplemented with technical aids such as radar and other instruments.

Maintaining a safe speed is essential at all times to react promptly to hazards and make correct decisions. Contributing factors include traffic density, maneuverability, potential obstacles, and weather conditions.

The risk of collision is the decisive point for altering or maintaining course. A key indicator is the approach of another vessel at a constant bearing.

When boats or yachts are on a direct collision course, they pass port-to-port, i.e., both must keep to the right of the neighboring vessel.

On crossing courses, the vessel that has another ship to its right must yield. The vessel with the right of way must maintain its position and speed to avoid danger.

Sailing vessels apply right-of-way rules with each other depending on their position relative to the wind:

The tack is determined by the sail position and the vessel's direction relative to the wind line. The windward side is opposite the side with the mainsail or the largest fore-and-aft sail. Maneuvering is carried out by heading up, reducing sail area, or falling off.

A drifting vessel must, upon the approach of another participant in maritime traffic, cease drifting and act according to the general rules.

When overtaking, the overtaken vessel maintains its course and speed, while the overtaking vessel must clearly signal its intended maneuvers. All other vessels in the vicinity must keep clear of the maneuvering area.

Depending on technical condition or specific activities, there are special rules for separation of sailing vessels from such ships.

Fishing vessels equipped with nets, gear, trawls, and other equipment have priority when passing other motor and sailing boats. If the fishing vessel's equipment does not impede its maneuverability, it has no priority over other participants and proceeds under general rules.

Sport and recreational fishing from a yacht does not qualify the vessel as engaged in fishing.

Movement around a fishing vessel is recommended at a sufficient distance to avoid entanglement with gear.

As a rule, special water areas free of other vessels are allocated for seaplane takeoffs and landings. Maneuvering a seaplane presents certain difficulties, and oncoming movements follow the rules for motorboats.

Vessels with a deep draft relative to the depth of the course in the navigation area have extremely limited ability to change course and speed. Their only option is to slow down and reverse. Such ships should be given a clear passage without requiring maneuvers.

The COLREGs classify as vessels restricted in their ability to change course those engaged in various underwater operations: cable laying, installation and repair of navigation equipment, hydrographic and seabed surveys. This category also includes supply and personnel transport vessels, tugs, and minesweepers.

While carrying out their operational activities, such vessels cannot change course or location except in cases of extreme danger. Other ships are advised to pass them at a sufficient distance.

In maritime practice, vessels not under command are ships with damaged propulsion, steering systems, or hulls, rendering them unable to maneuver fully. To maintain navigational capability, they must maintain a constant course and speed, granting them right of way when encountering other vessels.

Civilian vessels must yield to formations of military ships and must not cross their formation. When performing special tasks or exercises, individual naval vessels display special signals or gaff lights. If a military vessel is not engaged in exercises, all COLREGs requirements apply to its navigation and right-of-way situations.

All actions at sea must be clear and unambiguous to all traffic participants.

Responsibility for safe navigation lies with the captains of both vessels.