In answer to the previously asked question here is an exert from the "Rules of the Road" (Sea), relating to diving operations, rule 27 e is more relevent to the vessel size we generally use! I haven't bothered with all the other related rules as they don't apply.
NOTE - the A flag IS THE SPECIFIED INTERNATIONAL SIGNAL, the Red White flag is a more localised signal (generally areas of US influence (like bouyage)). (Displaying of lights etc is related to vessel size).
Rule 27 Vessels Not Under Command or Restricted in Their Ability to Maneuver d) A vessel engaged in dredging or underwater operations, when restricted in her ability to maneuver, shall exhibit the lights and shapes prescribed in subparagraphs (b)(i),(ii) and (iii) of this Rule and shall in addition when an obstruction exists, exhibit: - (i) two all-round red lights or two balls in a vertical line to indicate the side on which the obstruction exists;
- (ii) two all-round green lights or two diamonds in a vertical line to indicate the side on which another vessel may pass;
- (iii) when at anchor, the lights or shapes prescribed in this paragraph instead of the lights or shapes prescribed in Rule 30.
(e) Whenever the size of a vessel engaged in diving operations makes it impracticable to exhibit all lights and shapes prescribed in paragraph (d) of this Rule, the following shall be exhibited:- (i) Three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;
- (ii) a rigid replica of the code flag "A" not less than 1 meter in height. Measures shall be taken to ensure its all-round visibility.
Please Note Rule 2 below
Rule 2 Responsibility (a) Nothing in these Rules shall exonerate any vessel, or the owner, master, or crew thereof, from the consequences of any neglect to comply with these Rules or of the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case. (b) In construing and complying with these Rules due regard shall be had to all dangers of navigation and collision and to any special circumstances, including the limitations of the vessels involved, which may make a departure from these Rules necessary to avoid immediate danger. You must attempt to avoid collision, even if this means that you turn the wrong way etc - primarily you must avoid endangering the vessel, thus you must avoid collision if at all possible. If you do ram or do not give way if a likely collision is imminent you would also be prosecuted as contributing to the incident. This is as I understand it.
This is why Andy turned away at the last minute - he could not intentionally risk a collision, even though he was in the right. He also turned to starboard as specified in the rules.