Guide to R-O-W Rules - Selected Definitions-Part 2

A word in italics (or bold italics) in the Racing Rules of Sailing for 1997-2000 (the RRS) has a special meaning that is given in the Definitions section of the RRS. To properly understand a rule that uses a defined word you must separately consider and understand the special meaning of the defined word. Only those defined words used in the r-o-w rules, Part 2 (When Boats Meet), are discussed here or in Selected Definitions - Part 1. Abbreviations, such as r-o-w, are explained in the Introduction.

Obstruction	*Obstruction* An object that a boat could not pass without changing course substantially, if she were sailing directly toward it and one of her hull lengths from it. An object that can be safely passed on only one side and an area so designated by the sailing instructions are also obstructions. However, a boat racing is not an obstruction to other boats unless they are required to keep clear of her or give her room.
– Overview	Obstruction determines the objects at which Section C, Rules 18 and 19, can apply. Used in Rules 18.1, 18.2, 18.3, 18.4, 18.5, 19.1 and Two-Length Zone.
– Basic	An obstruction is any object that would require a boat to make a substantial course change to avoid if she were one of her hull lengths from it and headed directly toward its center. A course change of 20-30° or more is certainly substantial. It is clear that an object (except another boat that is also racing) is an obstruction based solely on its size and it does not matter whether a boat can actually avoid it by a minor course change. A boat of similar size that is sailing on a course at right angles to your course satisfies the "substantial change of course" requirement (since if you were one boat length from it and headed directly at it you would have to alter course substantially to avoid it).
– Advanced	A boat that is racing is an obstruction to other boats only if they are required either to keep clear of her or give her room. Thus, giveway boats are generally not obstructions.
– Examples	• In Example 1, two Ps are sailing on a windward leg on a converging course with a S of similar size. Since both Ps are required to keep clear of S under Rule 10 (On Opposite Tacks) [P must keep clear of S], S is an obstruction as to both Ps.
	• In Example 2, three boats are sailing downwind on slowly converging courses. S and P are on the outside and PW is between them. S is an obstruction to both PW and P since both of them must keep clear of her under Rule 10 (On Opposite Tacks) [P must keep clear of S]. P is an obstruction to PW but not to S since only PW (and not S) is required to keep clear of P under Rule 11 (On the Same Tack, Overlapped) [W must keep clear of L]. Under Rule 10, P must keep clear of S so P cannot be an obstruction to S.
– Related	Because an object is an obstruction does not automatically mean that a boat has rights under Rule 18 (Passing Marks and Obstructions) or Rule 19 (Room to Tack at an Obstruction). That will depend on whether boats are overlapped and passing the obstruction on the same side [Rule 18] or whether a substantial course change is required to avoid the obstruction [Rule 19].
Proper Course	*Proper Course* A course that 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.
– Overview	Proper course determines what will be a "proper course" for purposes of Rules 17.1, 17.2 and 18.4. Used in: Rules 17.1, 17.2 and 18.4.
– Basic	A "proper course" is one the boat would sail to finish as quickly as possible. Since different sailors often have different ideas of the quickest route to get to the finish line there can be more than one proper course for a boat at any particular point in time. Thus, two boats sailing side by side may have different proper courses because of differing views on how best to get to the finish line as quickly as possible.
– Advanced	For a particular course to be "proper" it must be one that you would have sailed even if the other boat mentioned in the rule imposing the proper course restriction had not been there. Under 17.1 (On the Same Tack; Proper Course), a proper course for L may take account of any boat except a W she has overlapped to leeward from clear astern. Under 17.2 (On the Same Tack; Proper Course), a proper course for AH/W may take account of any boat except one that is AS or L and aiming to pass to leeward of her. And, under 18.4 (Gybing), a proper course for IN with r-o-w may take account of any boat except an overlapped giveway O. So, it is only the boat that is imposing the proper course restriction (i.e., the boat as to which the proper course restriction actually applies) which may not be considered in determining whether a particular course is a proper one.
– Examples	• In Example 3, L and W are approaching the finish line to finish. L believes she will finish more quickly by sailing slightly higher and crossing the finish line closer to the windward end. Since L believes that sailing to finish nearer to the windward end of the finishing line will let her finish as quickly as possible her course is a proper one. On the other hand, W believes she will finish more quickly by sailing slightly lower and finishing closer to the leeward end of the line. Since W believes that she is sailing to finish as quickly as possible her course is a proper one also. [Under Rule 11 (On the Same Tack, Overlapped), however, W must keep clear of L so W's proper course is not relevant. See Rules 11 and 17.1.]
	• In Example 4, M and W are about to pass to windward of L. Rule 17.1 applies to M and she may not sail above a proper course while she is within two of her boatlengths of W (see the Examples for Rule 17.1). M wants to pass L at least two boatlengths to windward of her so that L will not be able to luff M. M's course to avoid L is proper since it is one she would have sailed in the absence of W. In this example, W is the "other boat referred to in the rule using the term" so M's proper course must be one she would have sailed in the absence of W. Accordingly, M's proper course may properly take into account any boats other than W.
– Related	Proper course is only relevant to Rules 17.1, 17.2 and 18.4.
Racing	*Racing* A boat is racing from her preparatory signal until she finishes and clears the finishing line and marks or retires, or until the race committee signals a general recall, postponement, or abandonment.
– Overview	Racing determines when most of the r-o-w rules and many of the other rules will apply. Used in: Preamble to Part 2 and Rule 22.1.
– Basic	A boat is racing from her preparatory signal until she has both finished and cleared the finishing line and marks. This is significant because a boat can only be penalized for breaking a r-o-w rule or hitting a mark while she is "racing."
– Advanced	"Clears the finishing line and marks" does not mean leaving the vicinity of the finishing line or the race course, only getting (a) completely over the finishing line and (b) away from the vicinity of the finishing marks so as not to be in danger of hitting them. If you later sail back near a finish mark and hit it then at that point you are no longer "racing" so you have not broken Rule 31.1 (Touching a Mark).
– Related	A boat that is not racing may be DSQed for breaking Rule 22.1 (Interfering with Another Boat) if she interferes with a boat that is still racing.
Room	*Room* The space a boat needs in the existing conditions while manoeuvring promptly in a seamanlike way.
– Overview	Room determines what "room to keep clear," "room to pass a mark or obstruction" and "room to tack" will mean. Used in Rules 15, 16, 18.2, 18.5 and 19.1.
– Basic	Room is the space needed by a boat in the existing conditions to perform a particular maneuver promptly and in a seamanlike way. There are three "maneuvers" for which room may be required: (1) keeping clear of a r-o-w boat [Rules 15 & 16], (2) passing a mark or obstruction [Rule 18] or (3) tacking to avoid an obstruction [Rule 19].
	There are several important elements within the definition of "room." One element is "existing conditions," so that the space required for a particular maneuver will vary depending on what conditions (wind and sea) exist at the time (and may also vary depending on the size and type of boats involved). A second element is "seamanlike way," so that a boat will only be entitled to enough room to complete a particular maneuver properly (and will not be entitled to the room necessary to "mess up" the maneuver). A third element is "promptly," so a boat is only entitled to the space to make a particular maneuver "promptly" and may not delay in making a particular maneuver if that causes her to take more room than she would have needed if she had acted promptly.
– Advanced	The idea of room to perform a tack or gybe is not specifically mentioned in the definition. Nevertheless, where a tack or gybe is required as integral to "passing" a mark, for example, then "[t]he space a boat needs" to pass the mark should certainly include the room necessary to perform any required tack or gybe.
– Example	• In Example 5, IN and O are overlapped and rounding a leeward mark, leaving it to starboard [they are overlapped despite being on opposite tacks because Rule 18 (Passing Marks and Obstructions) applies to boats on opposite tacks at a leeward mark]. Under Rule 18.2(a) (Giving Room; Keeping Clear), IN is entitled to room to "pass" the mark and will have to gybe to properly round the mark. O is so close to IN that when IN gybes her boom hits O's shrouds. Since IN is passing no farther from the mark than good seamanship would require, O does not leave IN enough room to properly "pass" the mark (which "passing" required her to gybe) and so breaks Rule 18.2(a) by failing to give IN enough "room." See the Examples for Rule 18.2(a).
– Related	See the discussion of "Room" in Important Concepts.
Tack, Starboard or Port	**Tack, Starboard or Port** A boat is on the tack, starboard or port, corresponding to her windward side.
– Overview	Starboard tack and port tack relate to which boat will have r-o-w under Rule 10 (On Opposite Tacks). Used in: Rules 10, 11, 18.1, 18.3, 19.1 and Clear Astern and Clear Ahead; Overlap.
– Basic	This definition is the same as the commonly understood meaning. A boat is always on either starboard or port tack.
– Advanced	When a boat is head to wind she will still be on the tack she was on immediately before she became head to wind (since her windward side does not change until after she has gone past head to wind). Note that the old IYRR concept of "tacking" (meaning from the time a boat is past head to wind until she is on a close-hauled course) is eliminated and so under the RRS "tacking" is not defined and merely means changing from one tack to another by going past head to wind.
– Related	If a boat is gybing she will be on the new tack based on when her leeward and windward sides switch. This will be when the mainsail fills on the new side (or more precisely, when the end of her boom passes through the wind).
Two-Length Zone	*Two-Length Zone* The area around a mark or obstruction within a distance of two hull lengths of the boat nearer to it.
– Overview	Two-length zone is used in Rule 18 (Passing Marks and Obstructions). Used in Rules 18.2 and 18.3.
– Basic	This is an area around a mark or obstruction with a radius of two hull lengths of the boat nearer to it..
– Advanced	Under Rule 18.5 (Passing a Continuing Obstruction), the two-length zone does not apply at a continuing obstruction.