Avoiding collisions at sea starts long before two vessels become dangerously close. Two of the most important requirements in the International Regulations for Preventing Collisions at Sea (COLREGs) are deceptively simple:
- Rule 5 – Keep a proper lookout
- Rule 6 – Proceed at a safe speed
They apply to every vessel, from a small powerboat or sailing dinghy to a superyacht or commercial ship. Understanding what they mean in practice is fundamental to safe boating.
Rule 5 – Keep a Proper Lookout
Rule 5 – The IRPCS Wording
“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.”
Rule 5 – The Explanation
COLREG Rule 5 requires every vessel to maintain a proper lookout at all times. That means using:
- Sight
- Hearing
- All available means appropriate to the prevailing circumstances and conditions
The purpose of the lookout is not simply to spot other vessels. It is to build a full picture of what is happening around your boat and identify whether a risk of collision is developing. A good lookout should be monitoring:
- Other vessels, Their apparent direction and speed
- Navigation marks
- Swimmers, paddleboarders and other small craft
- Fishing gear and Floating debris
- Changes in visibility
- Weather
- Shoreline hazards
- Traffic from astern or from blind areas
The important words are “at all times.” A lookout is required in broad daylight, at night, in fog, when travelling quickly and when moving slowly through a harbour. Looking forward is not enough. One of the most common weaknesses we see when training small craft boaters is a tendency to concentrate almost entirely on what is directly ahead. A proper lookout should cover 360 degrees around the vessel. This is particularly important aboard powerboats and RIBs.
A vessel approaching from astern may be overtaking you. A fast-moving PWC could appear from one quarter. A sailing yacht may emerge from behind your console, canopy or another vessel. Before altering course, it is good practice to look behind and check the area into which you intend to turn. Think of it much like checking your mirrors and blind spot before changing lanes in a car.
Use Your Ears
Rule 5 specifically mentions hearing. Sound can provide valuable information, especially in restricted visibility. Listen for;
- Another vessel’s engine
- A fog signal
- A ship’s whistle
- Someone shouting a warning
- Alarms
- Breaking water around an obstruction
- VHF transmissions
This becomes particularly important at night and in restricted visibility. Music, headphones or other distractions can therefore undermine an effective lookout and should be discouraged.
Electronics Help – But They Do Not Replace the Lookout?
Modern boats may have an impressive range of electronic aids, including:
- Radar
- AIS
- Chartplotter
- Electronic charts
- Depth sounder
- Thermal camera
- VHF radio
These can substantially improve situational awareness. They do not remove the requirement to look outside. Radar can detect targets that are difficult to see visually, while AIS can provide valuable information about suitably equipped vessels. However, not every vessel carries AIS and not every target will necessarily appear reliably on radar. Small dinghies, kayaks, paddleboards, swimmers and small unlit craft may be particularly difficult to detect electronically.
The COLREGs therefore require navigators to use all available means appropriate to the circumstances, rather than relying on one source of information.
Look Out by RADAR vs AIS
While the IRPCS make frequent mentions of RADAR they do not include AIS. While AIS is a valuable tool, always be mindful that it is presenting information that has been transmitted from another vessel and you can not be 100% sure of its accuracy. A trained RADAR operator however is interpreting information him/herself and will be aware of the possible errors. While this is a subtle difference it is an important one. You must not blindly trust another vessel’s AIS transmission as being correct, that vessel’s equipment may be faulty and may be transmitting false information.
Rule 6 – What Is a Safe Speed?
Rule 6 – The IRPCS Wording
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 concentrations of fishing vessels or any other vessels;
(iii) the manoeuvrability 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 draught 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.
Rule 6 – The explanation
Rule 6 requires every vessel to proceed at a safe speed.In harbours there is often a maximum speed set as a bylaw by the harbour authority, beyond harbour limits there is deliberately no universal speed such as “6 knots” or “10 knots” that is automatically safe. A safe speed is one at which you can take proper and effective action to avoid a collision and stop within a distance appropriate to the circumstances. That means a speed that is perfectly safe in one situation may be dangerously fast in another. Most readers will immediately appreciate that piloting a vessel at nigh is likely to require a slower speed than by day.
Factors Affecting Safe Speed
Among the factors that should be considered are:
- Visibility. Fog, rain, spray, darkness and glare can dramatically reduce the distance at which hazards can be detected. Reduced visibility will usually require reduced speed.
- Traffic Density- A high speed that might be perfectly reasonable in open water may be inappropriate in a busy harbour. Think about:
Commercial traffic, Sailing fleets, Fishing vessels, Dinghy racing, PWCs, Paddleboards - Harbour entrances. The more traffic around you, the more time and space you may need to assess what everyone is doing.
- Manoeuvrability. Different vessels turn and stop very differently. A lightweight RIB may respond almost instantly to helm and throttle. A large displacement vessel may need hundreds of metres — or considerably more — to stop. Even your own boat’s manoeuvrability changes with:
- Speed
- Load
- Sea state
- Wind
- Current
- Water depth
- Background Lighting. At night, shore lighting can make other vessels surprisingly difficult to identify. Navigation lights may disappear amongst street lights, harbour lighting and illuminated buildings. Safe speed therefore requires consideration of what you can actually see and interpret.
- Wind, Sea and Current. Strong tides can dramatically change your speed over the ground and the time available to make decisions.
Wind and waves can also reduce manoeuvrability and visibility. - Navigational Hazards. Shallow water, rocks, moorings, harbour walls and narrow channels may restrict the direction in which you can manoeuvre. Having fewer escape routes means you may need more time to make decisions. Reducing speed creates that time.
Safe Speed Is Not Simply About the Speed Limit
Harbours and rivers often have local speed limits. Complying with the speed limit does not necessarily mean you are travelling at a safe speed.
Imagine a harbour with a 6-knot limit. Six knots might still be far too fast if:
- Visibility is only a few metres
- A marina entrance is congested
- Children are sailing nearby
- You are passing moored vessels
- A paddleboarder is directly ahead
- The vessel cannot safely stop in the visible distance
A speed limit is generally the maximum permitted speed. Rule 6 still requires the skipper to decide whether conditions require something slower.
Faster Boats Need to Look Further Ahead
Speed has a major effect on how quickly a situation develops. At:
- 5 knots, a boat travels about 2.6 metres every second.
- 20 knots, it travels about 10 metres every second.
- 40 knots, it travels more than 20 metres every second.
- At 40 knots, just ten seconds represents more than 200 metres of travel.
That means the faster you travel, the further ahead your lookout must extend. It also means distractions become increasingly dangerous.
Looking down at a chartplotter, adjusting the radio or checking a phone for only a few seconds can allow a fast boat to travel a surprisingly large distance without anyone properly watching ahead.
Use of Radar
Rule 6 separates the factors into those applying to all vessels and additional factors applying to vessels with operational radar. Part b specifically covers vessel fitted with radar. Additional factors when radar is fitted includes things such as:
- characteristics, efficiency and limitations of the radar;
- limitations imposed by the range scale in use;
- sea state, weather and other interference;
- possibility that small vessels, ice and other objects may not be detected;
- number, location and movement of radar targets;
- more exact assessment of visibility where radar is used.
Key Points to Remember for Rule 5 and Rule 6
A safe passage depends on far more than knowing which vessel theoretically gives way. Remember:
- Maintain a proper lookout at all times.
- Look behind as well as ahead.
- Use sight, hearing and all appropriate available equipment.
- Do not rely solely on AIS, radar or a chartplotter.
- Travel at a speed appropriate to the actual conditions.
- A harbour speed limit is not automatically a safe speed.
- Faster boats need to look much further ahead.
- An attentive skipper travelling at an appropriate speed has time.
- Time to see.
- Time to assess.
- Time to communicate.
- And most importantly, time to act.
Maintaining a proper lookout and choosing a safe speed are therefore not simply requirements of the COLREGs. They are two of the foundations of good seamanship.
Doug Innes
RYA Navigation Instructor Trainer