This rule emphasises the importance of always maintaining a proper lookout using sight, hearing, and all available tools to evaluate the situation and the risk of collision.

The officer on watch should regularly patrol the bridge, carefully scanning the horizon, with special attention given to the blind sectors of the radar. In cases of reduced visibility, it is essential to assign extra lookouts, including one positioned forward to provide early detection of sounds or objects. To achieve comprehensive situational awareness, the officer on watch should make effective use of various tools at their disposal, including radar, AIS, ECDIS/Charts, VHF, and Navtext. These tools provide valuable information about nearby vessels and potential hazards.

The first part of Rule 6 emphasises that all vessels should maintain a speed that allows enough time to detect a potential collision and manoeuvre to avoid it. The points below discuss various factors that affect the speed required for collision avoidance.

A vessel navigating in fog should be conscious of the actual range at which a potential danger is first detected, allowing for speed adjustments to provide ample time to take appropriate action.
Another example, adjusting vessel speed for transverse currents or winds in constrained waters, where a faster speed might be preferable to avoid significant drift or substantial counter-heading.
Remember, the factors given are some examples that should be considered, meaning there may be others that are not listed.

The following acronym could help in remembering the factors for part a:
VTS-BMW

• Visibility.
• Traffic density.
• State of weather. (current, wind and sea)
• Background lights.
• Maneuverability.
• Water depth.

An easier way to remember the factors for vessels carrying radar is by breaking it down into simplified sections
Radar set up:

To make a full assessment of the situation, the OOW should be using all available means to determine if a risk of collision (ROC) exists. Depending on the conditions, the OOW would be using certain methods to determine if a ROC exists. Lastly, if in any doubt, treat the situation as a ROC.

If the situation occurs during the day with clear visibility, sight would be the most reliable method as you could make out the true aspect of the vessel and the actual bearing. Then you would use other available equipment to get a full assessment. However, if the situation occurs during restricted visibility, then radar and listening for sound signals would be your best sources to determine if a risk of collision (ROC) exists.

This section is all about detecting objects early. To do this, adjust your radar to scan further, which means increasing the range scale and using longer pulse lengths. S-Band radar is preferable for long-range detection. If Automatic Radar Plotting Aid (ARPA) is available, use it to gather movement data of detected objects. Without ARPA, you need to manually systematically plot the object's positions.

Don't rush decisions based on limited information. Instead, gather a complete picture of the situation. Using radar, wait until the output data is steady and reliable, usually after three minutes. Verify the target by sight or AIS if possible, as radars can sometimes provide false echoes due to interference.

To assess collision risk, take frequent bearings and ranges of the object. You can take bearings using your ship's compass, the radar's electronic bearing line (EBL), or even by a transit line by lining up a fixed object on your ship with the potential hazard. Use the radar to measure ranges. If an object keeps a steady or close-to-steady bearing while getting closer, there's a collision risk. If you're unsure, remember point (a) of this rule: "If there is any doubt, such risk shall be deemed to exist."

When you find yourself in a situation where collision might happen, your actions to prevent it should be clear for other ships to understand, done early enough, and avoid putting other ships in doubt or danger.

When you change your course or speed to avoid crashing, it's important to make the change noticeable enough for other ships to see it. This means they should see a clear change in your position. Avoid making many small changes as this might confuse other vessels and make the situation unclear.

If you have a lot of space around your ship, a big and early change of course can be the best way to avoid a collision.

Whatever action you take to avoid colliding should result in your ship and the other passing at a safe distance. You should also keep checking that your action is working until the other ship is clearly past and safe.

Always remember that you can use the engines to keep your ship safe. It might be necessary to slow down or stop the ship to avoid collision or to buy time to evaluate the situation better.

• If "vessel A" should avoid blocking "vessel B's" course or "vessel B's" path which it can only safely navigate, "Vessel A" should act early to give "vessel B" enough sea room to pass.
• If the situation identifies as a risk of collision, "vessel A" must still keep out of the way of "vessel B". However, must bear in mind the other rules contained in part B.
• If the situation identifies as a risk of collision, "Vessel B" is not relieved of her duties to avoid collision according to the rules in part B.

"Vessel A" and "Vessel B" in an apparent crossing situation, "Vessel B" is CBD (constrained by draught) and appears to be on "Vessel A's" port bow with a starboard aspect.

• "Vessel A" detects "Vessel B" using long-range detection, notices there's no risk of collision, but to allow more sea room, she wishes to take early action.
  When taking action, you must adhere to all other applicable rules. If we look at rules contained in this part (Part B), we know rules 5-8 are always in play, then we have rules 18 which is given priority for understanding roles between vessels. Seeing there is no risk of collision, rule 15 does not technically apply, but it should not be disregarded. Therefore, any action for "Vessel A", including altering to port, is available. However, to remove any ambiguity, it's better to alter to starboard and adjust speed, as long as it doesn't involve in another dangerous situation.
• "Vessel A" detects "Vessel B" and notices there is a risk of collision.
  If we look at rules contained in this part (Part B), we know rules 5-8 are always in play, then we have rules 18 which is given priority for understanding roles between vessels. Seeing there is a risk of collision, rule 15 does apply and loosely links in rule 17, more specifically 17c where course alteration of port shall be avoided. Rule 18 takes precedence so "Vessel A" shall still take action to avoid "impeding" "Vessel B".
• "Vessel B" detects "Vessel A" and notices there is a risk of collision.
  If we look at rules contained in this part (Part B), we know rules 5-8 are always in play, then we have rules 18 which is given priority for understanding roles between vessels. Seeing there is a risk of collision, rule 15 does apply. However, Rule 18 takes precedence so "Vessel A" shall still take action to avoid "impeding" "Vessel B". Ensuring there is no false safety for "Vessel B", she must take action if there is a ROC, due to her condition she may not be able to alter course efficiently but she can adjust her speed.