Rule 5 — Look-out: The Foundation of Collision Avoidance

TL;DR — Every vessel, at all times, must maintain a proper look-out by sight and hearing and by all available means appropriate to the prevailing circumstances and conditions, in order to make a full appraisal of the situation and the risk of collision. 33 CFR §83.05

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What the Rule Says

The text of Inland Rule 5 is brief but absolute:

"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

Every word in that sentence carries weight on the exam. Break it down phrase by phrase:

"Every vessel" — No vessel is exempt. The rule does not distinguish by length, tonnage, vessel type, or operational status. A seaplane on the water is a vessel. 33 CFR §83.03 A WIG craft operating on the surface is a vessel. 33 CFR §83.03 A non-displacement craft is a vessel. 33 CFR §83.03 If it meets the definition of "vessel," Rule 5 applies to it without exception.

"At all times" — There is no time-of-day carve-out, no weather carve-out, no traffic-density carve-out. The obligation is continuous. This language is reinforced by the application rule: Rules 4 through 10 — which includes Rule 5 — apply in any condition of visibility. 33 CFR §83.04 That means Rule 5 applies in clear weather, in fog, in heavy rain, at night, and in sandstorms. 33 CFR §83.03

"Proper look-out" — The word "proper" is not defined in the Rules, but the exam tests its implications. A proper look-out is one that is adequate for the circumstances. A single helmsman staring at a chartplotter while transiting a busy harbor is not maintaining a proper look-out. The look-out function and the helm function are distinct duties.

"By sight and hearing" — Both modalities are mandatory, not optional. Sight alone is insufficient. Hearing alone is insufficient. This is especially significant in restricted visibility, where sound signals from other vessels — such as the one prolonged blast of a power-driven vessel making way 33 CFR §83.35 — are the primary means by which you detect traffic you cannot see. A vessel that has its engines running so loudly that the crew cannot hear approaching vessels is not maintaining a proper look-out by hearing.

"As well as by all available means appropriate in the prevailing circumstances and conditions" — This clause extends the look-out obligation beyond the unaided human senses. Radar, AIS, VHF radio monitoring, depth sounders, and any other equipment fitted and appropriate to the situation must be used. The phrase "available means" does not require equipment you do not have; it requires you to use what you do have. The phrase "appropriate in the prevailing circumstances" acknowledges that not every tool is useful in every situation, but the mariner must exercise judgment about which tools are appropriate and then actually use them.

"So as to make a full appraisal of the situation and of the risk of collision" — This is the purpose clause. Look-out is not an end in itself; it is the means by which the mariner gathers the information necessary to assess collision risk. A look-out that does not produce a full appraisal is not a proper look-out. This links Rule 5 directly to the downstream rules on risk of collision and action to avoid collision.

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Why It Matters on the Exam

Rule 5 applies in any condition of visibility. 33 CFR §83.04 This is one of the most frequently tested facts about the steering and sailing rules. Rules 11 through 18 — the rules governing conduct between vessels in sight of one another — apply only when vessels can be observed visually from each other. 33 CFR §83.11 By contrast, Rule 5 has no such limitation. Exam questions often present a scenario in restricted visibility and ask which rules apply. Rules 4 through 10, including Rule 5, always apply. 33 CFR §83.04

The look-out obligation is inseparable from restricted visibility operations. When visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or similar causes 33 CFR §83.03, the hearing component of Rule 5 becomes critical. A power-driven vessel making way sounds one prolonged blast at intervals of not more than two minutes. 33 CFR §83.35 A power-driven vessel underway but stopped and making no way sounds two prolonged blasts in succession with an interval of about two seconds between them. 33 CFR §83.35 A vessel not under command, a vessel restricted in her ability to maneuver, a sailing vessel, a vessel engaged in fishing, and a vessel engaged in towing or pushing sounds one prolonged blast followed by two short blasts at intervals of not more than two minutes. 33 CFR §83.35 A manned vessel being towed, or the last vessel of a tow if more than one vessel is towed, sounds one prolonged blast followed by three short blasts at intervals of not more than two minutes. 33 CFR §83.35 Recognizing and correctly interpreting these signals is only possible if the look-out is actively listening — which Rule 5 requires. 33 CFR §83.05

"In sight of one another" is a defined term. Vessels are deemed to be in sight of one another only when one can be observed visually from the other. 33 CFR §83.03 Radar contact alone does not constitute being "in sight." This distinction matters because the rules governing crossing, overtaking, and head-on situations — Rules 11 through 18 — apply only when vessels are in sight of one another. 33 CFR §83.11 Rule 5, by contrast, applies regardless. 33 CFR §83.04

Vessel definitions affect who is bound by Rule 5. Because "every vessel" is bound by Rule 5, and because "vessel" includes every description of water craft including non-displacement craft, WIG craft, and seaplanes 33 CFR §83.03, exam questions may test whether a seaplane taxiing on the water must maintain a look-out. The answer is yes.

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Common Pitfalls

Pitfall 1: Confusing "underway" with "making way." A vessel is underway when she is not at anchor, not made fast to the shore, and not aground. 33 CFR §83.03 A vessel can be underway but making no way through the water — for example, a power-driven vessel that has stopped her engines and is drifting. Rule 5 applies to that vessel. The sound signal for such a vessel in restricted visibility is two prolonged blasts, not one. 33 CFR §83.35 Candidates sometimes confuse the look-out obligation with the making-way status; the look-out obligation does not depend on whether the vessel is making way.

Pitfall 2: Assuming Rule 5 only applies in restricted visibility. Because look-out is so obviously critical in fog, candidates sometimes mentally file Rule 5 under "restricted visibility rules." It is not. It is a steering and sailing rule that applies in any condition of visibility. 33 CFR §83.04 The restricted visibility rules (Rule 35 and others) are separate obligations layered on top of the always-applicable Rules 4 through 10.

Pitfall 3: Treating radar as a substitute for a visual look-out. Rule 5 requires look-out by sight and hearing as well as by all available means. 33 CFR §83.05 Radar is one of those available means, but it does not replace the sight and hearing requirements. A vessel relying solely on radar while no one is watching or listening is not in compliance with Rule 5.

Pitfall 4: Believing small vessels are exempt. There is no size threshold in Rule 5. Compare this to Rule 35, where vessels less than 12 meters in length are not obliged to give the prescribed fog signals but must make some other efficient sound signal. 33 CFR §83.35 Rule 5 contains no such exemption. Every vessel means every vessel.

Pitfall 5: Conflating "vessel restricted in her ability to maneuver" with "vessel not under command." A vessel not under command is one that, through some exceptional circumstance, is unable to maneuver as required by the Rules. 33 CFR §83.03 A vessel restricted in her ability to maneuver is one that, from the nature of her work, is restricted in her ability to maneuver. 33 CFR §83.03 Both categories sound the same fog signal — one prolonged followed by two short blasts 33 CFR §83.35 — but they are distinct definitions, and exam questions test whether candidates can correctly classify a described vessel.

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Quick Check

Q1: Rule 5 applies in which conditions of visibility?

Rule 5 applies in any condition of visibility. Rules 4 through 10, which include Rule 5, are not limited by visibility conditions. 33 CFR §83.04 33 CFR §83.05

Q2: A seaplane is taxiing on the water. Is it required to maintain a look-out under Rule 5?

Yes. The word "vessel" includes any aircraft designed to maneuver on the water. 33 CFR §83.03 Rule 5 applies to every vessel. 33 CFR §83.05

Q3: Two vessels detect each other only by radar in restricted visibility. Are they "in sight of one another" for purposes of Rules 11–18?

No. Vessels are in sight of one another only when one can be observed visually from the other. 33 CFR §83.03 Radar contact does not satisfy this requirement. Rules 11 through 18 therefore do not apply; Rules 4 through 10 — including Rule 5 — do apply. 33 CFR §83.04 33 CFR §83.11

Q4: What sound signal does a sailing vessel make in restricted visibility, and under which rule?

A sailing vessel sounds one prolonged blast followed by two short blasts at intervals of not more than two minutes. 33 CFR §83.35 This signal is the same as that used by a vessel not under command, a vessel restricted in her ability to maneuver, a vessel engaged in fishing, and a vessel engaged in towing or pushing.

Q5: A vessel is underway but has stopped engines and is making no way through the water. What fog signal does she sound, and how does Rule 5 apply to her?

As a power-driven vessel underway but stopped and making no way through the water, she sounds two prolonged blasts in succession with an interval of about two seconds between them, at intervals of not more than two minutes. 33 CFR §83.35 Rule 5 applies to her at all times regardless of her making-way status; she must maintain a proper look-out by sight and hearing and by all available means. 33 CFR §83.05

Q6: A vessel less than 12 meters in length is anchored in restricted visibility. Is she required to ring a bell every minute?

No. A vessel of less than 12 meters in length is not obliged to give the prescribed bell signals, but if she does not, she shall make some other efficient sound signal at intervals of not more than two minutes. 33 CFR §83.35 Note, however, that Rule 5 still requires her to maintain a proper look-out at all times. 33 CFR §83.05