Rule 5 — Keeping a Proper Look-out

What the rule requires

One sentence is the entire rule: "Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision." 33 CFR §83.05

The International text reads the same, and the supplied comparison is explicit that Inland Rule 5 is word-for-word identical to it. COLREGs Rule 5 That is the first thing to bank. A look-out question labelled "(International Only)" and the same question labelled "(Inland Only)" have the same correct answer, and a candidate who hesitates over divergence here is spending time on a trap that does not exist.

Every exam item on this topic is built out of one of five clauses:

Every vessel — the duty attaches to the vessel, without qualification by length, tonnage, class or number of persons aboard. The rule names no exception, so any answer option that carves one out is wrong on its face.
At all times — there is no visibility condition, no daylight condition and no underway condition in the text. Fog does not switch the rule on and a flat calm at noon does not switch it off.
By sight and hearing — both, not either. Hearing is the half candidates drop, and it is the half that produces the fog-signal questions.
By all available means appropriate in the prevailing circumstances and conditions — sight and hearing are the floor, not the ceiling. The standard rises with what is aboard and what the conditions demand; equipment that is fitted and working is an available means, and whether it is appropriate is answered by the prevailing circumstances.
So as to make a full appraisal of the situation and of the risk of collision — this is the purpose clause and it is the test of whether a look-out was proper. Detection alone does not satisfy it. The look-out must be sufficient to appraise the risk of collision.

Applicability sits one rule earlier. Under the International Rules, Rule 4 puts this section in force in any condition of visibility, and the supplied text flags that Inland Rule 4 is not the same, directing a comparison against 33 CFR §83.04 on any question that turns on which set applies. COLREGs Rule 4 For look-out itself that comparison changes nothing, because the two Rule 5 texts are identical.

You are anchored in a designated anchorage in dense fog, main engine secured, waiting on the tide. Is a look-out required?

Yes. The duty runs to every vessel and applies at all times, with no exception for a vessel at anchor and none for a vessel with her engine shut down. Any option reading "only when underway" or "only when making way" is inventing a condition the rule does not contain.

Telling it apart

The single criterion is what switches the rule on, and Rule 5 sits on one side of that line by itself.

Rule 5 — look-out. In force at all times, in any condition of visibility, whether or not another vessel has been detected. Most often misfiled as a restricted-visibility rule, because candidates first meet it in fog scenarios.
Rule 11 and everything under it. These rules apply only to vessels in sight of one another. COLREGs Rule 11 A radar contact you have not seen, and a fog signal you have only heard, do not satisfy that condition.
Rule 15 — crossing. Applies when two power-driven vessels are crossing so as to involve risk of collision, in which case the vessel which has the other on her own starboard side keeps out of the way and, if circumstances admit, avoids crossing ahead. COLREGs Rule 15 Misfiled when a candidate assigns give-way and stand-on roles off a bearing taken from a sound signal.

Rule 15 also carries a warning worth carrying out of this lesson: the supplied comparison flags Inland Rule 15 as differing from the International rule. The identity of the two Rule 5 texts is a fact about Rule 5, and it does not travel to its neighbours.

Working a question

Take the published sample stem: you are underway in heavy fog, you hear the fog signal of a vessel somewhere ahead, and you are asked which action you are required to take. The four options are all plausible ship-handling. Work the rules in force before working the options.

Confirm Rule 5 is in force. It is, and it was before the signal was heard. "Every vessel" and "at all times" leave nothing to establish. 33 CFR §83.05
Notice that the stem is Rule 5 working. You heard the signal — that is the hearing limb of the look-out doing its job. On a vessel where engine noise, a stereo or a closed wheelhouse masks that signal, the look-out has already failed, and it has failed before any manoeuvring rule was ever reached. This is why the exam writes hearing into fog stems.
Test whether the other vessel is in sight. She is not. You have a sound bearing and nothing more. Rule 11 conditions the whole in-sight section on vessels being in sight of one another, so none of that section is available to you here. COLREGs Rule 11
Strike the option that assumes otherwise. The option pairing "maintain speed" with five short and rapid blasts responds as though there were a vessel in sight to respond to. Step 3 removes it, and it removes any option that would name you stand-on or give-way, since those roles come out of the section Rule 11 governs. COLREGs Rule 15
Choose among what is left on the restricted-visibility rule. The three remaining options are all speed responses, and the one that is correct is set by the conduct-in-restricted-visibility rule, which is its own topic and its own lesson. Rule 5 got you the contact; it does not choose your speed.

That last step is the discipline the exam rewards. Rule 5 questions proper are decided on one of five clauses, and the moment a stem asks what must you do with the engines, you have left Rule 5.

Same fog, same signal, but this time your radar shows a single target fine on the starboard bow at 1.2 miles, closing. Are you now in sight of her?

No. A radar contact is not sight of the vessel, and Rule 11's condition is not met, so the crossing rule and the give-way and stand-on roles remain unavailable. What the radar contact does establish is that radar was an available means appropriate to the prevailing circumstances, and that using it was part of the look-out required by Rule 5.

Where candidates lose the point

The option reading "a proper look-out must be maintained in restricted visibility" attracts because every fog stem on the exam features one. It is beaten by at all times, reinforced by the section being in force in any condition of visibility.
The half-quote distractor is the most expensive one on this topic. An option will read "by sight and hearing" and stop there, next to an option that reads "by sight and hearing as well as by all available means appropriate to the prevailing circumstances." Both look like the rule. Only the second one is, and the clause the short option drops is exactly the clause that brings radar and every other fitted aid into the look-out.
The mirror error is the option restricting look-out to the electronics: a watchstander working radar and AIS from the chart table with nobody using their eyes and ears. The rule names sight and hearing first and adds all available means to them.
A candidate operating single-handed picks the answer that a look-out is required only where crew are carried, or that a dedicated hand must be posted. The duty in the rule is placed on every vessel and is a duty to maintain a look-out. Read the option against those words, not against your own manning.
Detection gets mistaken for compliance. An option describing a watch that sights a vessel and does nothing further can look adequate until the purpose clause is applied: the look-out must support a full appraisal of the situation and of the risk of collision.
Divergence gets over-applied. Having learned that International and Inland differ on much of Part B, a candidate hedges on look-out and second-guesses a correct answer. Rule 5 is identical under both. Rule 15 is not.

Check yourself

A question is labelled "(International Only)" and asks by what means a proper look-out must be maintained. Does the International label change your answer?

No. Inland Rule 5 is word-for-word identical to the International rule, so the means required are the same under either set: by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions.

Visibility is unlimited, the sea is flat and you have no contacts in sight. Your radar is fitted and operable. Must it be used?

The rule requires all available means appropriate in the prevailing circumstances and conditions, so the question is answered by conditions rather than by preference. An operable radar is an available means; whether it is appropriate is decided by the circumstances at the time. An answer option asserting that radar never needs to be used in clear weather, or that radar alone satisfies the look-out, fails the wording in opposite directions.

You hear a fog signal broad on the port bow. You are power-driven, and you reason that any vessel to port would be the give-way vessel. Do you stand on?

No. The rules that create stand-on and give-way roles apply only to vessels in sight of one another. A sound signal is not sight, so Rule 11's condition is not met and the crossing rule is not engaged.

Your deckhand asks whether the look-out can be stood down while you are alongside the fuel dock hoses on and then again while making the harbour approach in daylight. What governs?

The words at all times. The rule sets no daylight exception and no low-workload exception, and it attaches to every vessel.

Two power-driven vessels are crossing in clear weather with risk of collision, and each has the other in sight. Which one keeps out of the way, and what should she avoid?

The vessel which has the other on her own starboard side keeps out of the way, and if the circumstances of the case admit she avoids crossing ahead of the other vessel. Take the "in sight of one another" condition as satisfied before applying this — that is what puts the crossing rule in play at all.

You know Rule 5 reads identically in both sets. Can you carry that assumption into a Rule 15 crossing question?

No. The comparison supplied for Rule 15 flags a difference from the International rule and directs you to 33 CFR §83.15 for the Inland text. Identity is established rule by rule, and Rule 5 is the one you can rely on.

An answer option states that a look-out is proper if the watchstander sights every vessel that comes over the horizon. Sufficient?

Not as written. The rule sets the object of the look-out as a full appraisal of the situation and of the risk of collision, so sighting without appraising risk of collision does not meet the standard the rule states.