Safe Speed

Rule text#

Every vessel shall at all times proceed at a safe speed so that she can take proper and effective action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions. In determining a safe speed the following factors shall be among those taken into account:

(a)By all vessels:

(i)The state of visibility;

(ii)The traffic density including concentration of fishing vessels or any other vessels;

(iii)The maneuverability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;

(iv)At night, the presence of background light such as from shore lights or from back scatter of her own lights;

(v)The state of wind, sea, and current, and the proximity of navigational hazards;

(vi)The draft in relation to the available depth of water.

(b)Additionally, by vessels with operational radar:

(i)The characteristics, efficiency and limitations of the radar equipment;

(ii)Any constraints imposed by the radar range scale in use;

(iii)The effect on radar detection of the sea state, weather, and other sources of interference;

(iv)The possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;

(v)The number, location, and movement of vessels detected by radar;

(vi)The more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity. [USCG-2012-0102, 79 FR 37912, July 2, 2014, as amended by USCG-2012-0102, 79 FR 68621, Nov. 18, 2014]

(a)By all vessels:

(i)The state of visibility;

(ii)The traffic density including concentration of fishing vessels or any other vessels;

(iii)The maneuverability of the vessel with special reference to stopping distance and turning ability in the prevailing conditions;

(iv)At night, the presence of background light such as from shore lights or from back scatter of her own lights;

(v)The state of wind, sea, and current, and the proximity of navigational hazards;

(vi)The draft in relation to the available depth of water.

(b)Additionally, by vessels with operational radar:

(i)The characteristics, efficiency and limitations of the radar equipment;

(ii)Any constraints imposed by the radar range scale in use;

(iii)The effect on radar detection of the sea state, weather, and other sources of interference;

(iv)The possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range;

(v)The number, location, and movement of vessels detected by radar;

(vi)The more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity. [USCG-2012-0102, 79 FR 37912, July 2, 2014, as amended by USCG-2012-0102, 79 FR 68621, Nov. 18, 2014]

Why it shows up on the exam#

Rule 6 lists factors to be taken into account — visibility, traffic density, manoeuvrability, lights at night, state of wind/sea/current, draft. Memorise the list.

Authoritative source#

Source links checked against the current public rule corpus on 2026-05-16.

• 33 CFR §83.06 — the section this text comes from, with its neighbours.
• International COLREGs Rule 6 verbatim text is published by the IMO and is authoritative for international waters.

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.