In the last version of our Rules (2009-2012), the philosophy of our game remains unchanged - with overriding emphasis on safety (both  yours and that of others who may need your help) and fair, sportsmanlike sailing.

1997 brought an increased emphasis on avoiding collisions - especially those that could cause damage. Rule 14 (Avoiding Contact) indicates that, once it becomes clear the burdened boat will not be keeping clear, the right-of-way boat shall avoid contact if reasonably possible. There is however no penalty for the right-of-way boat unless the collision that could have been avoided actually causes damage.

DEFINITIONS:

Three definitions deserve very special attention since they affect the interpretation of a number of crucial rules:

Room is: The space a boat needs in the existing conditions while manoeuvering promptly in a seamanlike way.
Two main situations in which you must know exactly what is meant by the word room are
1. Rule 16: this requires a right-of-way boat to alter course only in such a way that the give-way boat will have room to keep clear (see also the keep clear definition below)
2. Rule 19: Room to Pass an Obstruction

Mark-Room  is Room for a boat to sail to the mark, and then room to sail her proper course while at the mark. However, mark-room does not include room to tack unless the boat is overlapped to windward and on the inside of the boat required to give mark-room.
The only Rule that this new definition relates to is the new Rule 18: Mark-Room.

Keep Clear  One boat keeps clear of another if the other can sail her course with no need to take avoiding action and, when the boats are overlapped on the same tack, if the leeward  boat can change course in both directions without immediately making contact with the windward  boat.

One other crucial definition is:
Proper Course A course a boat would sail to finish as soon as possible in the absence of the other boats referred to in the rule using the term. A boat has no proper course before her starting signal.
As we shall see below, a number of our rules require us to sail proper course when we are close to other boats in certain situations. Proper course is not necessarily the straight-line course to your next mark. It can be any course that might get you to the finish line the fastest but not a tactical course that you are sailing against the boat(s) whose presence is requiring you to sail proper course.

An example of this would be a run where a boat within 2 boatlengths of me is steering a course to pass me to leeward. Let us assume that boat establishes a leeward overlap within 2 lengths of me. While that situation exists, Leeward is not permitted to sail above proper course. An obvious proper course here would be the straight-line course to the next mark.
However, Leeward's proper course might be to sail high of the mark under certain circumstances such as leeward-setting current or sailing "up in a lull". When I am on the Protest Committee, I tend to look for some consistency in and/or valid reason for the course - i.e. the boat claiming to be sailing proper course in the example above should have been allowing for current or sailing "up in the lulls, down with the puffs" before the windward boat became an issue.

Another example of a valid reason for a proper course that departs from the obvious shortest course would be the following: I am inside at the gybe mark and am supposed to gybe in such a way that I sail proper course (as per Rule 18.4). It is however, a windy day, and I wait for a surfable wave on which to gybe. Because this move reduces wind pressure (and the risk of capsize!) during the gybe, I can defend this as my proper course since it is the same course I would sail if no other boat were near by.

Finally, if you are going to be selective about how much time you want to spend on learning the Rules and do not want to memorize all the definitions, there are two more of them that it pays to be very familiar with:

• Clear Astern and Clear Ahead; Overlap  One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat's hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern. However, they also overlap when a boat between them overlaps both. These terms always apply to boats on the same tack. They do not apply to boats on opposite tacks unless rule 18 applies or both boats are sailing more than ninety degrees from the true wind.

• Finish A boat finishes when any part of her hull, or crew or equipment in normal position, crosses the finishing line in the direction of the course from the last mark, either for the first time or after taking a penalty under rule 44.2 or, after correcting an error made at the finishing line, under rule 28.1.

GENERAL:
Apart from the need to avoid collisions that I mentioned earlier, two rules items are particularly worth looking at:

• the Two-Turns Penalty is now standard - but please note that rule 44.2 requires you to get "well clear of other boats as soon as possible" and do your turns. If you think about it for a while and/or decide to pick a nice, convenient time for your turns, your turns do not exonerate you from your foul and you are still subject to protest for the original infraction.

• Changing Course: Rule 16.1 states: ”When a right-of-way boat changes course, she shall give the other boat room to keep clear.” No exception! And note the two defined items just covered above - room and keep clear. 

• opposite tacks: port boat keep clear of starboard!
• same tack: windward boat keep clear of leeward and overtaking boat keep clear!
• tacking: tacking boat keep clear of a boat that is not tacking!

BEFORE THE START:
After spending some time studying rules-related matters to prepare for this article, it comes as somewhat of a shock to me that I - and I suspect, most of the rest of us - could have been DSQ'd in numerous races since the new rules came into effect in '97. Just have a look at this hypothetical example:

With 8 minutes to go to the Wayfarer start, I am sailing along on a starboard tack reach about 30 metres behind the line. I meet a port tack Fireball who starts in 3 minutes. The latter bears away and goes to leeward of me.

Do I hear you ask: "So, what's wrong with that??!!" Well - have a look at rule 22.1 which says
If reasonably possible, a boat not racing shall not interfere with a boat that is racing.
By definition, you are racing once your Prep Signal (usually 4 minutes before your start as per rule 26) has been made. The preamble to the right-of-way rules (Part 2) says that you are subject to protest/penalty over one of these rules only while you are racing unless you broke rule 22.1! In that case, you are supposed to retire from the race because Two-Turn Penalties are limited to atoning for a possible Part 2 infringement committed while racing. (This rule does however apply only while you are "in or near the racing area" and it does say "if reasonably possible".)

What this says to me is that, from now on, I'm going to be much more careful not to interfere with any boat that is racing - both before I start racing and after I stop racing in any particular race.

The new rules are mostly the same for before the start as after - e.g. luffing:  no limitations except as per Rule 16 (see above), no more mast abeam (anywhere) in the new rules.

There is even buoy room when you're just dawdling around before the start
                            BUT
when you're approaching the starting line to start, the mark-room rule (rule 18) does not apply unless the starting mark in question is not surrounded by navigable water (e.g. one end of the line is a dock)

You should also be aware that there is no proper course before the start signal goes! This means that - subject to the limitations of rule 15 (Acquiring Right of Way) and 16 (Changing Course), even a leeward boat that came up from clear astern is entitled to luff a windward boat head to wind if she so desires (although she must do so in a way that gives windward room to keep clear).

THE BEAT:
Tacking is now "defined" in Rule 13 which remains the same in intent - but the onus has been removed from the tacking boat. The new rule basically says you must keep clear of other boats while tacking. This is supplemented by Rule 15 (Acquiring Right of Way) which requires you to “initially” give the freshly burdened boat “room to keep clear” if you tack into a right-of-way position.
 

Another fairly common upwind situation worth noting is the one on the left: Two port tackers are sailing side by side when they meet a starboard boat. Since both port boats will have to keep clear of starboard, starboard (S) rates as an obstruction. The leeward port tacker (PL), who has right of way over the windward port tacker (PW) is allowed to choose how he wishes to deal with this obstruction: If PL wants to tack, he can call Port Windward for "Room to Tack" (rule 20) but must do so in plenty of time to allow Port Windward to respond.

If PL chooses to pass astern of S, PL must give PW room to pass astern of S also, if PW wants to do so (rule 19: Room to Pass an Obstruction).

AT THE WINDWARD MARK:
Many racers are under the mistaken impression that the rule 18 (the buoy room rule) does not apply at a windward mark. It does not apply only in one situation at the windward mark and that is when boats approach each other on opposite tacks!

Beware of trying to tack in a crowd right at the mark! Even if you ‘legally’ complete your tack in front of a boat but are (with any part of your boat!!) inside the Zone when you complete your tack, you are fouling if the other boat which is now coming up from astern and laying the mark, either has to luff above close-hauled or bear away and fails to properly pass the mark because she was avoiding a collision with the slower moving YOU! Furthermore, if the non-tacking boat establishes an overlap to leeward of you here, you don't even get the protection of rule 15 which in every other situation requires a boat which acquires the right of way to "initially give the other boat room to keep clear". It is a good rule of thumb that you should avoid tacking in(to) the Zone unless you are sure you can do so well away from all other boats!

Buoys to Starboard: Rule 18 does not often give you immunity to tack at a mark (e.g. if you are subject to rule 18.3 - see previous paragraph).  Thus, even if you get to the windward mark on starboard tack just ahead of another starboard tacker, you must keep clear of the other starboard tacker while you are tacking. To play it safe, what you do is briefly luff up to near head-to-wind right at the mark if there is a boat very close behind you. Once he starts to go by you to leeward, you can then complete your tack. It is also worth noting that, once you have started your tack, rule 16 prevents a boat close astern from altering course if such an alteration prevents you from keeping clear.

Hitting the mark: If you should hit any mark, rule 44 says that you must get "well clear of other boats as soon as possible" and do one turn including one tack and one gybe. As with a Two-Turns Penalty, if the Turn is not done as soon as possible, you might as well not have done it for all the good it'll do you in a potential protest!

If, God forbid, you should hit a mark and foul another boat in the same incident, you need only do a Two-Turn Penalty, not three turns. The Two-Turn Penalty is the maximum penalty for any one incident (rule 44.1) unless you "caused serious damage or gained significant advantage", in which case the One- or Two-Turn Penalty is not available to you and you must retire (rule 44.1).

THE REACH:
Luffing: If a boat is to windward of you or about to try to pass to windward, you are of course, allowed to defend your wind. However, in keeping with Rule 14 (Avoiding Contact) which forbids causing damage, and by Rule 16 (Changing Course) which requires giving the other boat "room to keep clear”, the sudden, violent luff is now decidedly frowned upon. And of course, as mentioned earlier, there is no more “Mast Abeam”.

Rear-ending another boat is in the same category as rear-ending another car. No matter how dumb the other guy was, legally you're in the wrong (rule 12).

THE GYBE MARK:
Buoy room at the gybe mark remains much the same as it always was (rule 18).

If two (or more!) boats are overlapped, the inside boat (leeward) is also the right-of-way boat even if buoy room did not apply and is thus entitled to make a “proper course” rounding (i.e. wide and close). However, the inside boat must gybe in accordance with the requirement to sail proper course (rule 18.4) - unless of course the wind has shifted or the course is skewed such that the second reach is very broad in which case the inside boat would be entitled to merely bear away to what she considers her proper course.

NOTE 1: If you claim a late change in overlap status - i.e. that you established or broke an overlap just before the Zone - and the other boat disagrees, you should take his word for it unless you have reliable witnesses to the contrary, since rule 18.2(d) states that "it shall be presumed" that the change took place too late!
NOTE 2: The buoy room “freeze frame” that determines overlap and entitlement to mark-room, is taken at the instant when the nearest boat's hull touches the Zone.

If two boats are not overlapped as they are about to round a mark, the boat clear astern must keep clear while the boat clear ahead rounds the mark except that the boat clear ahead is never given carte blanche to tack around the mark - i.e. she is always subject to rule 13 (While Tacking).    

THE LEEWARD MARK:  

At the leeward mark it is especially important to understand that you do not suddenly become the right-of-way boat just because you are inside at the mark. Rule 18 merely limits the actions of an outside boat that has right-of-way. In the diagram at right, W (windward) and L (leeward) are about to round the leeward mark to port. Even though the boats are in the Zone, L is still the right-of-way boat but rule 18 limits her actions to the extent that she cannot simply cut W off and prevent her from rounding this mark (the way she could if this were a starting line mark).

Beware! Rule 18.2(a) merely tells the outside right-of-way boat that she must give the inside boat mark-room (i.e. sufficient room to round or pass the mark - i.e. enough room to make a “seamanlike” rounding (close and close) as per the definition of room. In easy sailing conditions (flat water, moderate winds), a seamanlike rounding would likely be one in which W should, at all times during the rounding, be able to reach out and touch the mark.

THE RUN: The run brings about four situations that do not normally happen on a reach:  

Remember that the basic idea of “overtaking boat keep clear” only applies to boats on the same tack. Thus, if you are on a port tack run, beware of the boat coming at your transom on starboard! If you are P in the picture at left, you must get out of the way, or gybe! On the same tack, it is often easy to establish a leeward overlap from clear astern if you are on a broad reach or a run. If you have done this within 2 lengths of a windward boat, you must not sail above your proper course for the duration of that overlap. (Of course, a pair of gybes would start a new overlap!) You are however permitted to luff up above your proper course if by doing so you promptly fall clear astern of windward - e.g. you want to cross his transom in order to go up to windward of him.

Here, S is not subject to 16.2 but is still bound by 16.1 and must avoid any course change that would not give P room to keep clear.

THE FINISH:
The rules for finishing are unchanged – at least in intent. Things to remember are:

• the finish definition requires you to cross the line in the (general) direction from the last mark. So, if the RC boat is on the wrong side of the finish mark for buoys to port for example, the requirements of the Finish definition take precedence over the buoys to port requirement.
• while the Finish definition plus rule 28.1 state that you finish when the first part of your boat or crew in normal position crosses the line, and that the whole boat does not need to cross the line, you are nevertheless still racing until you have cleared the finish line.  And as long as you are racing you are subject to being penalized for breaking a right-of-way rule. If this should happen to you, your first crossing of the finish line would be null and void and you will not be counted as finished until you have properly re-crossed the line after doing your Penalty.
• and don't forget, even after you are no longer racing, you are subject to protest if you interfere with a boat that is still racing (e.g. take their wind, etc.) - and in this case, you can't do a Penalty to atone for your sin!