Following on from the original thread;

Unbelievably there are at least 9 separate Rules (10,11,12, 13,14,15,16,17 & 18), together with their sub sections (too many to count!)which have to be considered when a Port tack boat approaches a windward mark which has to be rounded to port.

Though the Rules appear to favour the right of way boat on Starboard and discourage Port tack boats from executing close quarter manouvers near the windward mark, in practice the Rules offer considerable defence to the Port tack boat if the right of way boat does not set itself up to anticipate what the Port tack boat may do. 

First of all let us consider some overriding issues which will impact on the situation;

• Rule 10 obliges the give way boat on Port to keep clear of a boat on Starboard and this basic rule is not overridden at the windward mark by any of the provisions of rule 18 which deals with mark room in the “Zone” (within 3 boats of the mark).
• Rule 14 requires boats to avoid contact if reasonably possible. An interesting part of this rule states that the right of way boat “need not act to avoid contact until it is clear the other boat is not keeping clear etc”. In other words, if it become clear to the right of way boat that the port tack boat is going to be in a position that a collision is inevitable, either before or after the port boat has executed any manouver, including a tack, and has to anticipate this by changing course before the port tack boat has completed its tack, the Port tack boat has broken the rules.
• The rules constrain the right of way boat from executing certain options, notably with regard to changing course and giving other boats the opportunity to keep clear while doing so, though 18.3(b) and 18.5 have an exception to this.

So how can the starboard boat legally ensure that it is not bullied by port tack boat while approaching the windward mark?

• The first defence is to discourage the port tack boat from tacking in front of you by bearing off in sufficient time and giving him the opportunity of to keep clear. You cannot alter course to prevent him keeping clear (16.1) while he is tacking, so it needs to be done before he starts his tack and gives him an adequate opportunity to keep clear.
• If a port tack boat is tacking in a position which requires you to anticipate avoiding a collision by changing course, he has broken rule 13 which requires a boat tacking to keep clear. The starboard boat should immediately protest having made a demonstrable alteration of course before the tack was completed.

• If a Port boat completes its tack without forcing the Starboard boat to take any collision avoiding alterations of course, the rights and obligations of the Starboard boat are different whether the tack was undertaken inside or outside the Zone.

            Outside the Zone

            The Port tack boat is now on starboard and has become the right of way boat. The other boat did not have to anticipate completion of the tack and the newly tacked boat has to give room to allow the other boat to keep clear. The newly tacked boat can luff provided room is given to allow the other boat to keep clear, unless she needs to shoot head to wind to round the mark when there is no requirement to give the weather boat room to keep clear.

            Inside the Zone

The rules work slightly differently if the tack is executed inside the Zone. If the tack is completed in front of or to leeward of a Starboard boat fetching the mark and she has to luff above close hauled to avoid the recently tacked boat then it is a penalty. If the original Starboard boat decides to bear off and gets an overlap to leeward of the recently tacked boat, this boat must keep clear and give mark room. The tactic for the original Starboard boat should be to luff above close hauled or bear off and establish an overlap to leeward and luff back up to your proper course which may included shooting the mark.  Basically if the starboard boat is smart the recently tacked boat can only get away with what it did if it ensures it stays clear ahead until it has rounded the mark.

Basically late approaches to the windward mark by boats on port should only work legally if the boats on starboard are well above the layline or the Port tack boat can execute a tack and remain clear ahead of existing Starboard boats until she has rounded the windward mark.

In my view the rules are far too complicated and inadequately protect the Starboard boats approaching the windward mark on the layline. This is compounded by the fact that Rule 18.2 (e) is switched off at the windward mark. How can it be fair for a port tack boat to bully his way into a stacked line of Starboard boats which cannot physically give room because of congestion and speed.

A much simpler approach would be to adopt a rule as follows;

Boats on port tack may not tack within the zone unless, on completion of the tack, they are able to remain clear ahead of any boats approaching the mark on Starboard until they have rounded the mark.

I suspect  Real Rules  Buffs will say that is exactly what the rules effectively state at the moment but if that is the case, it is not sufficiently clear to some of us.