COLREG Rule 5: The Impossible Lookout Requirement

“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.”

This is COLREG Rule 5—the foundational requirement for maritime collision avoidance. For commercial vessels with dedicated bridge watches and professional crews, it’s achievable. For recreational sailors, particularly those on long passages or sailing short-handed, it’s a legal fiction that creates dangerous paradoxes.

The Commercial Standard vs. Recreational Reality

Commercial vessels interpret Rule 5 through the lens of professional operations: dedicated lookouts, structured watch schedules, and clear chains of command. The law was written with this model in mind, and collision litigation often hinges on whether proper lookout procedures were followed.

But recreational sailors operate in a completely different reality. A couple on a 40-foot sailboat crossing an ocean doesn’t have the luxury of dedicated lookouts. They’re cook, navigator, sail trimmer, mechanic, and watchkeeper—often all at once. The idea of maintaining a “proper look-out by sight and hearing” at all times isn’t just difficult; it’s physiologically impossible.

The Fatigue Problem: Brain Capacity Under Stress

Even when sailors are technically “on watch,” their cognitive capacity varies dramatically with fatigue levels. Research on sleep deprivation shows that mental performance degrades catastrophically after extended wakefulness:

• After 17 hours awake: Cognitive performance equivalent to 0.05% blood alcohol
• After 24 hours awake: Equivalent to 0.10% blood alcohol (legally drunk in most jurisdictions)
• Microsleeps: Brief 3-15 second lapses in consciousness that occur involuntarily when severely fatigued

Now consider the recreational sailor on day four of a passage, running on fragmented sleep, trying to interpret complex radar returns or AIS targets while hand-steering through a shipping lane. Their brain isn’t operating at full capacity—it’s running on reserves, with degraded reaction time, impaired judgment, and reduced situational awareness.

The cruel irony: Rule 5 demands that this exhausted sailor maintain a “full appraisal of the situation,” precisely when their brain is least capable of doing so.

The Weakest Link: Inexperienced Crew Under Pressure

On many recreational vessels, the “crew” is a spouse, friend, or child with limited maritime experience. When the experienced skipper needs rest, this less-experienced person takes the helm. They’re legally responsible for maintaining the same “proper look-out” as a professional bridge officer, despite potentially having:

• Limited understanding of navigation lights and rules
• No training in radar or AIS interpretation
• Minimal experience judging vessel speeds and courses
• High stress levels from the responsibility

The result is predictable: the weakest link in the lookout chain isn’t equipment failure—it’s human capacity under real-world conditions.

The “All Available Means” Trap

Rule 5’s requirement to use “all available means appropriate in the prevailing circumstances” creates a perverse legal incentive. The more safety equipment you install, the higher the standard you’re held to.

A boat with radar, AIS, autopilot, and chart plotter is expected to use all of it effectively. If a collision occurs and investigation shows the radar wasn’t properly tuned or the AIS alarm wasn’t set, the skipper may be found negligent—even if they were exhausted from days at sea.

Meanwhile, a boat with minimal electronics faces lower expectations. They’re only required to use what’s “available,” and if nothing sophisticated is aboard, the legal standard drops accordingly.

The Sleepy Sailor Dilemma

Here’s the fundamental question that Rule 5 doesn’t address: What is safer—a sleep-deprived sailor maintaining a technically “continuous” watch, or a well-rested sailor who slept for 3 hours?

The law demands the former. Physiology suggests the latter is far more capable of responding to an actual emergency.

A sailor who hasn’t slept in 20 hours, staring at instruments with deteriorating comprehension, might tick the legal box for “maintaining lookout.” But when an actual collision risk emerges—a dark object in the water, an unexpected vessel maneuver, equipment failure—their reaction time, judgment, and physical coordination are all compromised.

The sailor who slept for 3 hours, waking refreshed to find a radar target at 5 miles, has far better odds of executing effective collision avoidance—despite having violated Rule 5 by not maintaining continuous watch.

What Would a Realistic Standard Look Like?

Rule 5 needs to acknowledge the physiological limits of small-crew recreational sailing. A more honest standard might look like:

• Acknowledge rest requirements: “Lookout shall be maintained except when crew rest is necessary for safe operation”
• Technology-assisted watch: Accept that automated collision avoidance systems (radar/AIS alarms) are the only practical solution for solo/short-handed sailors
• Risk-based approach: Higher lookout standards in congested waters, reduced requirements in open ocean
• Crew capacity consideration: Legal standards that account for crew size and experience level

Until the Rules Change…

Recreational sailors are left navigating an impossible contradiction: comply with a rule that’s physiologically unachievable, or accept that they’re technically in violation whenever they rest.

The real safety solution isn’t pretending humans can maintain continuous vigilance for days on end. It’s designing systems that work with human limitations—automated watch alarms, practical rest schedules, crew management that prioritizes cognitive capacity over legal compliance.

Because the exhausted sailor, desperately trying to stay awake to satisfy Rule 5, is far more dangerous than the rested sailor who slept when needed and woke with the clarity to handle an actual emergency.

The law says “at all times.” Biology says “that’s impossible.” Smart sailors listen to biology.