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Setting the course

Abstract

This chapter details general aspects of course geometry, for example having a combination of beating, reaching and running. Factors that may influence the choice of the course to be sailed are mentioned. Detailed procedures for setting the course, beginning with locating the Starting Vessel in a suitable Race Area and ending with setting the finishing line are given. Instructions to Course-setting boats are also included. The philosophy and the shapes of Triangle courses, the Windward/Leeward, the Trapezoid Inner and Trapezoid Outer are discussed - also considering the new focus on time rather than on distance. Finally, effects of wind changes and current are explained and possible measures to compensate are specified.

Contents

8.1 Course geometry
8.2 Location of the Race Area
8.3 Position of the Starting vessel and the leeward Mark
8.4 The starting line
    8.4.1 Length and direction
    8.4.2 Lineboat action
    8.4.3 Line bias
    8.4.4 Inner limit mark
    8.4.5 Correcting the line

8.5 The windward leg
8.6 Laying the other marks of the course
    8.6.3 The Olympic trapezoids (Inner and Outer Loop)
    8.6.4 The Windward/Leeward course
    8.6.5 The new Olympic triangle
    8.6.6 Type of course to choose

8.7 Adjusting a course for wind changes
    8.7.1 Race Committee action
    8.7.2 Windward leg
    8.7.3 Leeward leg
    8.7.4 Adjustment procedure
    8.7.5 New Olympic-type courses; shortening and lengthening of legs

8.8 Adjusting a course for currents
    8.8.1 General effects of a current
    8.8.2 Effect on the starting line
    8.8.3 Effect on the windward leg
    8.8.4 Effect on downwind legs
    8.8.5 General

8.1 Course geometry
Courses usually provide a combination of beating, reaching and running - each leg testing particular tactical and board handling skills. Exceptions are long-distance point-to-point races, where often changes in weather provide the variations desired. Class rules, too, may specify special requirements.

Whatever the course configuration, convention and common sense should play a part in the course selection. Courses should be consistent and not complicated. Even for a course around harbour marks, all mark roundings, where the rounding could be either way, should be consistently port or starboard. Port-hand roundings are often preferred at a windward mark, because they simplify observance of the port-starboard rule. Therefore, for major events, where there are no geographical constraints, a port hand course should always be used.

On a beat a fleet tends to spread out - the leaders have clear air and less interference.
On a run the leaders may be blanketed and the fleet closes up. Because of this and because an upwind start is the fairest, a race should start with a beat or have a beating leg as soon as possible after the start. These criteria are met by the simple upwind- downwind course.

Selection of the type of course to be used for a regatta, and indeed for a particular race within a series, will depend upon such factors as the area of water available, the anticipated wind strength and the speed of the competitors around the course. The Class rules, for certain (principal) events may describe the configuration desired although the Sailing Instructions can always override such a description, and indeed, on occasion, it may be necessary that they do so.

The course location should be selected to give as fair conditions as possible within the locality having regard for tidal currents, vagaries of wind caused by headlands and buildings, and shallows. It may be better to sail extra laps of a smaller size in order to avoid foul wind or foul ground, which introduce advantages from local knowledge.

8.2 Location of the Race Area
It is assumed here that the race course will be purposely set for the races that are to take place, using separate marks and starting and finishing lines to be positioned depending on the wind direction. When racing is to take place around fixed harbour buoys or landmarks, the positions of starting and finishing lines may vary depending on the wind direction.

If the Race Officer has to pick his own spot, the following applies: To set a course he will need to be competent in some basic geometry or enlist the services of someone who is. He will need a chart of the racing area showing relevant features which can be used for fixing positions, a cardboard shape or an outline on clear plastic film (e.g. overhead transparencies) of the desired shape made to the chart scale, instruments for transferring compass bearings to or from the chart, and a method of marking off distances.

In enclosed waters, the course shape will reveal how much flexibility the Race Officer has in placing the course with regard to the wind direction. It may also indicate to him that a starboard hand course is necessary, although a port hand course is always preferred to avoid congestion at the windward mark.

In open water, the procedure is simpler but there are fewer features and transits available to check the locations of the marks and therefore the length of the legs. The Race Officer is then dependent on carefully calculated time-distance runs in order to establish a windward leg of the length required.

These days, of course, Course-setting boats may have all sorts of navigation electronics on board. It makes sense, however, to know how to do it the old-fashioned way, in case the electronics should fail.

The following is a proven sequence for course-setting (continued throughout this chapter):

8.3 Position of the Starting vessel and the leeward Mark
If the wind is steady, move to a leeward location within the designated racing area. Locate the position on the chart by means of compass bearings, back-bearings, and transits, from identifiable features.

Record the average wind bearing and transfer it to the Starting vessel position on the chart. Remember that a wind vane must always be used in clear air, not where air flow is disturbed by a part of the Starting vessel. The best place is usually the bow.

Place the course shape described above on the chart to define the course and possible changes, to determine suitability with regard to foul ground, headlands, shipping channels, etc.

When satisfied, anchor the Starting vessel and recheck position. Note that the Starting vessel is always positioned at what will become the starboard end of the line.

When anchoring consideration should be given to letting out a little extra anchor line as this will give you the opportunity of making minor last minute adjustments to the starting line (before the preparatory signal) by either pulling in or letting out further anchor line.

Advise the other Committee vessels - and the other Race Officers, if any - immediately of your anchoring position and your wind direction. This information will help the other on-the-water-managers to establish their own courses and will avoid conflicts between neighboring race areas.

Continue to check wind direction.

8.4 The starting line

8.4.1 Length and direction
The next task is to lay the starting line, which needs to be of the required length. There are a number of rules of thumb for determining this. Commonly used guides are 1.1-1.5 times the sum of the lengths of the boards in the fleet. Some Race Officers regard this as too generous. The wind and sea conditions as well as the maneuverability of the racing boats should be considered.

The starting line needs to be nearly square to the wind. For this the Race Officer needs a wind vane with a 90 degrees sighting device or use of a hand-bearing compass. He takes up a position at the staff on board which defines one end of the line, and with the wind vane held in clear air, sights at 90 degrees to the vane. If this is not possible, use a hand-bearing compass. The line personnel on the Starting vessel should make sure that they can sight the line any time: they need to stand 1 metre behind the mast or pole which marks the starboard end of the line.

A simple method of checking the angle of the starting line is to wait until the starting vessel is laying either directly into the wind or in a direction parallel to the course to the first mark and then sight the pin mark along a bulkhead or some other right angled part of the starting vessel, this will give you a very accurate reference.

8.4.2 Lineboat action
The Lineboat proceeds in the right direction (wind direction minus 90?). Once the correct length has been reached (with a log, or time-on-distance calculation), the Lineboat drags the floating mark that is to form the pin end of the line in the water, but holds on to the weighted tackle.

This is done ideally in such a manner that the Race Officer can see the exact position of the weight. (This mark is often referred to as the "ODM", the Outer Distance Mark.) At a signal from the Race Officer, given when the floating mark is in position, the anchoring device is dropped overboard. The Race Officer may have to make some allowance for tidal flow, and in light conditions, the dropped weight tends to bring the mark forward.

Consideration can also be given using to using a flag and staff on the lineboat as the pin end mark. This has the advantage of the line boat always being in position to sight along the starting line and can also be used for making quick adjustments to the line as described in 8.3 above.

8.4.3 Line bias
It is customary to lay a starting line with approximately 5? of bias favouring the port end. The right-angled wind vane for line setting may be so constructed as to include a sight with this bias. The purpose of the bias is to encourage the fleet to make use of the whole line instead of just the starboard end. Too much bias may lead to congestion at the port end as everybody compete with each other to take advantage of it. The Race Officer should observe how the fleet reacts to the bias on his first starting line and adjust as required for subsequent starts. This requires the bias on the first start to be accurately set and known.

8.4.4 Inner limit mark
If an Inner Limit Mark ("ILM") is required it may now be laid. This mark protects the Starting vessel from competitors and gives barging boats the opportunity to harmlessly pass on the wrong side of the mark and restart rather than ram the Starting vessel or another boat. An Inner Limit Mark should be set as near as possible to the line but never more than a board length to leeward of it. If it is too far to leeward, competitors may be able to pass between the mark and the line towards the Starting vessel while still satisfying RRS 29.1 and 30.1.

To protect the Starting vessel an alternative is to project from the stern of the Starting vessel, a mark on a pole, which then forms part of the Starting vessel. It also keeps competitors away from a stern anchor warp if one is used.

8.4.5 Correcting the line
Remember that under RRS 27.2, the Race Committee may shift a starting mark at any time prior to the Preparatory Signal or, put the other way, all starting marks must be laid not later than the Preparatory Signal. Thus, with subsequent starts the starting line cannot be adjusted without delaying the starts.

See also paragraph 8.8.2 below, which deals with the effects of current on the starting line. For information how to deal with starting problems related to the starting line, please see also Chapter 9.3 and Section D on Racing Rules and Race Management Policies.

8.5 The windward leg If there is going to be a leeward Mark in front of the starting line (Mark 3 in the "old" Olympic course; Mark 2 in case of the windward- leeward course), the Course-setter sails halfway down the line, then heads up 90? ending up head-to-wind and dropping the Mark approximately 0.1 to 0.2 NM (or less) to windward of the middle of the starting line.

The first windward leg is thus extended.
When satisfied that the wind is steady enough within its fluctuations to warrant course setting, dispatch the Course-setting boat with specific instructions that will give the desired course length and direction, e.g., for a windward leg of 1 NM and a wind of magnetic bearing 55?, the instruction would be: "From the leeward Mark, proceed 55 degrees at 20 knots for 3 minutes".

From the chart, provide information, which will enable the Course-setting boat to check its position. The Race Officer may be able to calculate the compass bearings of two identifiable features or there may be a harbour feature close enough for a reliable assessment of distance. Keen competitors will be quick to complain if a significant error is made and then the whole Race Management is called into question. When the course boat is in position to lay the weather mark he should radio the Race Officer on the starting vessel who should then the course boats position and confirm that it is the correct position to lay the mark.

The above is a possible procedure if everything goes well. Sometimes wind or tide or both combine to frustrate the Race Officials. In light winds the Starting vessel may not stay on station but drift with the tide. Stern anchors are to be avoided if possible but if one must be used it should be laid with a weighted warp and marked with a buoy If a GPS is being used to lay the course either of the following procedures should be adopted.:

A. When the starting vessel is on station it can plot it's position on a chart using the GPS or by any other means. The course chosen for the race is then plotted on the chart and the coordinates for each of the marks are calculated and relayed to the course boat that then puts the coordinates into the GPS as way points.

The course boat then simply proceeds to the waypoints and lays the appropriate marks. For course changes the procedure is repeated. This assumes that the starting vessel has a chart table or similar, large scale charts, the time and ability to plot the course and extract the information required and the means of relaying the detailed information (lat and long down to three decimal places) and that the course boat has a GPS that will easily allow the input of manual waypoints.

This method does not allow for fine-tuning of the course prior to the preparation signal, as time may not allow new coordinates to be plotted and relayed to the course boat. It also makes "eyeballing" the weather mark ands getting a good wing mark difficult.

B. The course boat acting upon instructions from the start boat to lay the weather mark at say "1nm on a bearing of 195 degrees" proceeds to the center of the start line and enters that position as a waypoint of the GPS, way point 10 for example and records this waypoint number as the center of the start line. The boat then proceeds up wind for 0.1-0.2 n.m. and positions the leeward mark (as per paragraph 1 in section 8.5). After allowing the mark to settle the course boat approaches along side and enters that position as the next waypoint (eg 11), and records this number as the leeward mark. The coxswain then calculates the back bearing of 195 degrees (015 degrees) and sets the GPS into "goto" mode and nominates the waypoint for the leeward mark (number 11 in this example).

The course boat then heads off on a bearing of 195 degrees with the coxswain checking the back bearing via GPS. When the bearing and distance to the waypoint is 015 degrees and 1 n.m. the coxswain checks with the start boat to ensure the course boat is in the right position and to allow for any changes in wind direction. If given directions to move left or right the back bearing on the GPS will change and this can be used to calculate the new wind direction. After the weather mark is laid and allowed to settle the course boat approaches alongside and enters that position as the next waypoint (eg 12) and records this number as the weather mark.

The coxswain calculates the bearing to the wing mark and sets the GPS to "goto" waypoint 12 in this example. The coxswain then proceeds in the direction of the wing mark using the back bearing on the weather mark to correct any drift. When the back bearing and distance to the weather mark (12) is correct the coxswain can select "goto" waypoint 11 to double-check this position against the leeward mark. Once this mark has been laid it's position should be entered as another waypoint (13).

If a trapezoid course is being used then this can obviously be extended. If a change of course is required the start boat then relays the course using the stored leeward mark as the reference point. This method also means that the course boat can check any of the marks for drift by comparing their current position against the GPS waypoints.


8.6 Laying the other marks of the course Up to this point the procedure is the same, no matter what type of course is used, as long as it starts with a beat.
Some years ago, there was really only one acceptable course to lay, especially in open waters. This was the so-called Olympic Course, which consists of a triangle, a loop (the sausage) and a final beat. Sometimes it would have an extra triangle added and be called the super-Olympic Course. Many course experiments have been taking place, and the result has been the introduction of a number of new Olympic courses in respect of the 1996 Olympic games. However, experiments will go on and produce new course options. For the courses most frequently used at the time the current Racing Rules of Sailing 1997-2000 was issued, see also RRS N, Addendum A (Illustrating the Course).

In the following sections the particulars of all types of courses will be described. Which course is to be selected is usually a decision for the Race Committee and the Class(es) involved. See also paragraph 8.8.5 of this Chapter.

8.6.1 The triangle-sausage course
The "old-style" course, is seldom being used in board sailing events anymore, and will not be described in detail.

The "old" triangle.

The first leg of the triangle is the windward leg, bounded by marks conventionally numbered "3" (the leeward mark) and "1" (the windward mark). The "apex" or "gybe" mark is conventionally numbered "2".

8.6.3 The Olympic trapezoids (Inner and Outer Loop)
The Inner and Outer Loop course have nearly the same course configuration, but the order in which the marks must be rounded is different. In addition, with the Inner Loop the leeward mark next to the starting line (now usually called Mark 4) is replaced by a Gate (4G), i.e. two marks lying at 90 degrees, approximately 6-8 boats lengths apart, to the windward mark. Either of these is to be rounded (port or starboard) when coming downwind from the windward mark and after having first sailed through this gate (passed between both marks from the direction of the windward mark).

On the Trapezoid Inner Loop boats sail:

S-1-4G-1-2-3-F


First they sail a windward/leeward. After rounding Mark 1 for the second time they go on a short tight reach to Mark 2, then on a run to Mark 3, and then to the finishing line on another tight reach, leaving all marks to port. If the overall distance of that course seems to be rather short for the prevailing weather conditions, the Trapezoid Inner Loop can be extended by adding an extra windward/leeward: S-1-4G-1-4G-1-2-3-F (Trapezoid Inner Extra).



A Gate replacing a single leeward mark.

The Trapezoid Outer Loop consists of a beat, then a close reach, then a run, followed by a windward/leeward around Marks 2 and 3, and finally a tight reach to the finishing line, also leaving all marks to port:

S-1-2-3-2-3-F


Also the Outer Loop may be extended by an extra windward/leeward to a Trapezoid Outer Extra: S-1-2-3-2-3-2-3-F. As with the Inner Loop, the leeward mark 3 may be replaced by a Gate, mark 3 then becoming mark 3G.



The Olympic basic trapezoid courses. Left: the Outer Loop. Right: the Inner Loop.

Frequently, with more than one Class or various groups of the same Class on the course, the first fleet(s) will sail the Outer Loop and the later starters the Inner Loop. It is fair to say that the risk of congestion at the leeward mark is far greater with the Inner Loop, since there is no early reach to spread the fleet out a little.

Another option (not illustrated here) for the Trapezoid Outer Loop, at the Olympics 1996 offered to the Finn class, is having an upwind finish, with the finishing line being set windward to mark 2.

Usually the key factor in laying the Trapezoid courses is time, not distance. More wind means longer legs, while in less wind the course must be "shrunk". With an e.g. 45 -minute target, the marks are usually sufficiently close to lay the marks on eyesight. With the Inner Loop, again the Course Setter can afford to delay laying Marks 2 and 3 if he is expecting a wind shift.

The angle of at least one of the reaches is determined by the close-reaching characteristics of the Class(es) on the course. Trapezoid courses offer experienced Race Committees the possibility - if local conditions permit - to lay the final legs quite late, i.e., while the race is already underway. By doing this, the second windward/leeward leg can be adjusted to the wind direction if the Race Committee should find that its original choice of direction for the first windward leg was not the best one possible. There is thus a good opportunity to correct for e.g. the wind shift at a late stage and lay a perfect second beat, run and reach after the shift has come through. However, this adjustment is difficult or impossible with two fleets on the same course, one sailing the inner loop and the other sailing the outer loop.

The finishing line is located at the leeward end of the course, not far away from the starting area. This allows shorter time intervals between the finish of one race and the start of the next one. Remember that one of the reasons for the new courses is not only to allow shorter races, but also to be able to sail more races per racing day.

If the finish is on a reach the position of the Finishing vessel is very important; first, because it is more difficult to read the sail numbers of boats crossing the line on a reach than it would be if they were beating to windward; secondly, because racing tactics on the last reach could involve boats luffing in an attempt to force a competitor to the wrong (that is windward) side of the finish.

Experience so far has proven that the best place to position the Finishing Vessel is at the windward (port) end of the finishing line (a port hand course is assumed). It may be slightly more difficult to read sail numbers in this position, but it is safer than the leeward (starboard) end of the line, because competitors can see the finishing vessel itself much better than its anchor line and can therefore judge the amount of space available much better.

To solve the problem of reading the sail numbers, one option is to have a small boat at the starboard end of the finishing line (a port hand course is assumed), which records all the sail numbers without worrying about the exact finishing order. This boat does not need to anchor and could even position itself slightly to windward of the middle of the finishing line.

8.6.4 The Windward/Leeward course
This course only has two marks: Mark 1 as a windward mark, and Mark 2 as a leeward mark (otherwise also called Mark 3). Again, as with the Trapezoid Courses, the leeward mark may be replaced by a Gate (then mark 2 becomes mark 2G). This gate consists of two marks at a 90 degree angle to the windward mark (see 8.6.2. c.).

Windward and leeward mark will usually be laid to windward of the middle of the starting line. It is easily adjusted in the event of wind shifts, because no other marks need to be shifted to maintain the course configuration.

There are several options for the Windward/Leeward course: at the Olympics 1996, the leeward mark was replaced by a Gate and the finish was downwind. The marks to be rounded were:

S-1-4G-1-F


In addition, there was an option to sail an extra windward-leeward leg (Windward/Leeward Extra): S-1-4G-1-4G-1-F. As an alternative, there may be an upwind finish in a position to windward of mark 1 (see also RRS N, Addendum A).


The Windward/Leeward course, downwind finish.


The Windward/Leeward course, downwind finish, with an offset mark.

Some organizers prefer to use an offset mark at the windward mark to ensure that the leaders, on the downwind leg after rounding Mark 1, do not have to cut right through the fleet still coming up. An offset mark may also be used with triangle or trapezoid courses.

8.6.5 The M course


The Board M Course for sailboards.

A course sometimes used for sailboards, the Board M Course, is illustrated above.

8.6.6 Type of course to choose
The "new" course configurations (Trapezoid, Windward/Leeward) and the concept of running a greater number of shorter races (marks lying at shorter distances) have been in use for some years now and the response from the sailors tends to be increasingly positive. Small fleets occur typically at club level racing and the new, smaller courses when laid close to the harbour or club house, could raise more interest for yacht racing and possibly attract new sailors.

Some classes, however, prefer the "old" format with the triangular course and the longer races. It is really up to the organizers and the class(es) involved deciding what to do. One of the advantages of having different courses is that it allows a great deal of flexibility.

Organizers can now more easily give classes the product that they want. Even a mixture of courses during one event, the way big boats have had for many years, is possible. At any rate, organizers should not miss the opportunity to consult class representatives well before the event on what course the class prefers. Do not forget at this point that Race Management is a service to competitors.

8.7 Adjusting a Course for Wind Changes This section discusses the importance of a course being correctly oriented to the wind and how courses can be adjusted if the wind direction or the wind strength changes. It applies mainly to longer courses for which eyesight alone is not sufficient, and therefore makes reference to the "old" Olympic triangle course. However, the principles hold true for shorter courses just as much.

8.7.1 Race Committee action
At any time before the warning signal, by RRS 27.1, the Race Committee has to signal the course to be sailed. If necessary due to early changes in the wind direction or wind strength, RRS 27.1 allows the Race Committee to replace one course signal by another and/or signal that a designated short course is to be sailed.

If it has already given the warning signal, the Race Committee may then change a given course signal (still being before the starting signal) by postponing the race (RRS 27.3) and resetting the course.

After the start the Race Committee is limited by the Racing Rules and the Sailing Instructions. After the starting signal, RRS 32 (e) allows a Race Committee to abandon (or shorten) a race for any reason directly affecting the safety or fairness of the competition. This could include a major wind shift on the first leg. A race should not be abandoned due to a change in wind conditions after the leading boat has rounded the first mark. Abandonment should only be considered as an action of last resort in extreme circumstances where there is no reasonable opportunity to finish the race. Every effort should be made to finish the race by using all available means such as shortening or altering the course, shortening or extending the length of a leg of the course or any combination thereof

8.7.2 Windward leg On a windward leg boards should sail equal times on port and starboard tacks. If the leg is not true to the wind, sailing distance is reduced and the sailing area is reduced, too. In the left diagram below the sailing area on a beat, making good a track 45? to the true wind is shown. It is a square formed by boards sailing on opposite tacks from the leeward mark to the lay lines to the top mark. The right-hand diagram is the sailing area if the wind veers 30?. The sailing area is reduced by 50% and port tack sailing by 63%. If the wind veers 45? the sailing area becomes a line and the "beat" a procession to the top mark with the sailing distance reduced by 30%.



Left: a windward leg true to the wind. Right: effects of a 30? wind shift - reduced sailing area.

8.7.3 Leeward leg On the leeward leg, correct alignment to the wind is probably more critical. Assume the class is one that does not tack downwind and the optimum course lies within 10? of the true wind. If the course is true, midway down a 1.5 NM run, the competitors could be spread over a width of 490 m. Thus a board has room for initiative with respect to following shifts and tactical theories. If the leeward leg is at an angle of 10? to the wind, theoretically, for the boards assumed above, all competitors should remain on the same tack and sail on the same line to the leeward mark.

8.7.4 Adjustment procedure
Having established the importance of a course true to the wind, how is the course adjusted? Generally, an adjustment would not be made before the end of the first triangle. When an adjustment is made at this time, the whole course would be rotated about the leeward mark ('Mark 3' in a triangle course).

If the windward leg remains the same length, the old Mark 1 and the new Mark 1' form an isosceles triangle with the apex at Mark 3. To locate the position of Mark 1' the Mark boat proceeds from Mark 1 along the base of that isosceles triangle to the new position. The base is at 90 degrees to the line bisecting the other two sides. For example, if the bearing of the first leg was 255?, and the wind backs 30?, the new bearing of the leg is 225? and the average of the two bearings is 240?. The line at 90 degrees to the average is 150?. Therefore to lay Mark 1' the Mark boat steers 150? from Mark 1 until Mark 3 is on a back bearing of 225? minus 180?, that is 045?. This is shown in the diagram below.



Adjusting a triangle course (bold outline) by laying Mark 1' to 150? from Mark 1 and moving Mark 2 to a new position, thus rotating the (bold) triangle about Mark 3 (rotated triangle = dotted outline).

If a further triangle is to be sailed, Mark 2 will have to be moved in a similar manner. It the triangle was 45?-90?-45?, the old bearing of Mark 2 from Mark 3 was 210? (port hand course) and the new bearing is 180?. Therefore, the Mark boat steers 105? from Mark 2 until the bearing of Mark 3 is 360?. This is also illustrated in the diagram above.

It is a good practice to announce "standby for a course change", even if it is not proceeded with. The Race Officer must then take the decision, allowing his team enough time to execute course change. However, keep in mind, that any change in a race may cause errors and misunderstandings due to human failures or material shortcomings. Competitors might become irritated, confused or even misled when changes are not executed and signaled in due order. Do not try to be a perfectionist and consider properly if a minor change of the wind direction already requires a course change and, when positive, if your team will be able to manage the necessary action. Usually, a change of course is not necessary with wind shifts of 5-15?. Start thinking about a change of course when the wind shift turns out to be of 20? or more.

The actual procedure to do a course change could then be as follows: when the competitors are on the reaching legs of the triangle, a new bearing is determined for the windward mark and the Mark Boat or the Course Setter is instructed to proceed left or right according to whether the wind has backed or veered, until it is on the new bearing (see above).

Appendix 8A gives the appropriate tables, which combine the number of degrees of the shift with the length of the beat, thus giving the angle and distance that the Course Setter must navigate from the old Mark 1 to the new windward mark position. An alternative but more time-consuming procedure is for the Course Setter to proceed from Mark 3 (leeward mark) on the bearing of the new windward mark. If there should be a second triangle, then Mark 2 must also be reset. The new bearings for Mark 2 must be calculated and the attendant Mark Boat or the Course Setter be instructed accordingly.

The change does not have to be "completed", the mark may not be in position before the leading boat begins that leg, but in time to give it due notice of the change and display the bearing of that leg (see RRS 33). Similarly a new final beat can be set while the leading boats are on the square run.

The Mark Boat stationed at Mark 3 (the mark beginning the leg being changed) will receive orders from the Race Officer as to when to display code flag C and the approximate compass bearing to the new mark, and to make sound signals periodically. RRS 33, RRS Race Signals and RRS K 11 (Appendix 5B in this Manual) give the guidelines to deal with course changes.

Note that it is sometimes necessary to display one or more class flags under Code flag C, e.g. if the change applies only to some classes in the same race area or to a class whose leaders have overtaken the tail enders of a class which started earlier and which is still sailing the old (unchanged) course.

The Mark Boat (often the Lineboat, if it has finished its starting line duties) must be positioned close enough to the mark to ensure that the flag(s) and the compass bearings can be seen and the sound signals heard. It must, at the same time, leave a big enough gap to allow the fleet to get through.

The Sailing Instructions will have spelled out precisely how competitors are to take Mark 3 when the change in wind direction is greater than 90?. The instruction may provide for waiving RRS 28.1. For example: "When the course is changed, the competitors shall pass between the RC boat signaling the change and the nearby Mark, leaving the RC boat to starboard. In this case, RRS 28.1 is amended so that the string representing a boards wake shall touch either the Mark or the required side of the RC boat signaling the change of course."

8.7.5 New Olympic-type courses; shortening and lengthening of legs
When "new" Olympic-type courses are used, it will prove to be more difficult to adjust a course for wind changes while the race is underway. Usually the time available for moving a mark will be short (only a few minutes) and this will require a skilled Race Committee and fast course-setting vessels to make it work properly.

At the same time, it is less damaging than on the "old" course if one or two legs should be less than perfect by the time the fleet approaches them, because the races are short. With more races to be started there is always a chance to change the course before the next race. And with the option to lay the final legs very late, there is often a good chance that you can correct for a wind shift at a late stage and lay a perfect last run or beat to the finishing line.

In addition, as the focus with the shorter courses is rather on time than on distance, the Race Committee shall try its best to adapt the lengths of the legs to meet the scheduled target time for a race as near as possible. Competitors will not be happy to sail two races of 90-100 minutes duration each if they expect one race to last only 60 minutes. Likewise, races of a significantly shorter duration than expected will be unsatisfactory.

The Race Committee may react to changes in the wind strength by shortening or lengthening legs (could be combined with a change of course direction). A Mark boats then has to signal the change by displaying flag C and a '-' if the leg will be shortened or a '+' if the leg will be lengthened (see RRS 33). This gives the Race Committee the flexibility to adjust the length of a leg if the wind is moderating instead of e.g. having to shorten the course by one round. However, as every change increases the chance of an error, the Race Officer has to consider properly if a (especially minor) change of the length of a leg will make a material difference in the race.

It is difficult to give a rule of thumb when a course change of this kind should be signaled. If visibility is good and the mark to be moved is already in the water as the competitors round the prior mark, a change of 15-20% or more of the original length of the leg should be signaled. If visibility is poor, however, or the mark is not yet in place as the boards round the prior mark, even minor changes of the length should be signaled. Again, bear in mind that at all times a course change of the course direction must be signaled before the leading boat begins the leg being changed (see RRS 33), and that on short courses there will be very little time to put the mark in position.

When moving marks, a general guideline for any type of course should be that a mark that is no longer required for racing be removed as soon as the last boat has rounded it. Competitors can easily get confused if marks that are no longer used are left in their old positions, whilst other marks are moved to new positions. However, be sure that competitors do not get confused by towed marks: These marks may be wrongly identified as the actual marks in position.

8.8 Adjusting a course for currents

8.8.1 General effects of a current
We have considered the effects of wind changes on a course. Now we need to consider currents, usually tidal and therefore varying. Currents are particularly important, when relatively strong and associated with light winds. With anchored marks in a current it is not possible to set a course which is correct for all legs. However, this section considers how the elements of a course are affected by currents and how they may be adjusted.

When adjusting a course in a current a Race Officer must use considerable judgment. If significant adjustments are required it may be wise to delay or racing. With any current the apparent wind experienced by a sailor is different from that experienced on an anchored Committee boat. If the current is in the same direction as the wind, the apparent wind is less than the true wind and a close-hauled boat's track is further from the wind than its normal track. With the current in the opposite direction to the wind the apparent wind is greater and the boat's close-hauled track closer to the wind.


Effects of currents parallel to the wind.

With the current not parallel to the wind the direction of the apparent wind will change. With a true wind of 7 knots and a cross-current of 1 knot the apparent wind, for a board stationary in the water, is from 8? downstream of the apparent wind on an anchored Committee boat.


Effects of cross-currents, not parallel to the wind.

With a cross-current a beating boat, sailing equal times on each tack, will reach a point some distance downstream of a point directly to windward of its starting point.

8.8.2 Effect on the starting line
With a current parallel to, and in the same direction as the wind, a boat starting on starboard tack passes closer to the pin end mark than it would with no current. With a relatively strong current, boats starting on starboard tack near the pin end may have difficulty in clearing the mark. Some authorities recommend that in these circumstances the line should be biased to starboard to give starboard tack boards a greater opportunity to clear the line. However, the Race Officer must decide if starboard tackers should be favoured over port tack boards. An alternative method to compensate is to lengthen the starting line.


Effect of a current of the same direction as the wind, on boats starting.

Effect of a current parallel and against the wind.

If the current is parallel to and against the wind the most significant problem on the starting line is current-induced barging at the starboard end. This will most likely occur at the starboard end and more port hand bias will alleviate it. The use of a distance mark will protect the Starting vessel.

If there is a cross current the starting line should be approximately at a 90 degree angle, with appropriate bias, to the wind perceived by a boat stationary in the water. This can be calculated by vectors, or a luffing board can be observed or an unanchored Committee vessel can be asked to take a wind bearing.

A current will normally be constant during a start and therefore it is appropriate to consider adjusting a starting line to allow for it.

8.8.3 Effect on the windward leg
A current parallel to the wind changes the velocity but not the direction of the apparent wind. It also alters the track of close-hauled boards but no course adjustment is necessary to ensure equal times on each tack to reach the windward mark.

The correct bearing to a mark may be altered drastically by a cross-current. A cross-current carries boats downstream while they are beating and therefore the windward mark should be located downstream to ensure boats sail equal times on each tack and fulfill the ideal of maximum sailing area.

The correction required in a cross-current varies with the speed of the boards. The faster the less time they take to reach the top mark and therefore the smaller correction required. In our example in paragraph 8.8.1 above, with a true wind of 7 knots and a cross-current of 1 knot the apparent wind was from 8? downstream of the true wind.

If speed in these conditions is 4 knots and boards sail at 45? to the apparent wind, the windward mark should be set 26? down the current of the Starting vessel.

This leads to a rule of thumb for a cross-current. Assess the difference between the wind directions for competitors and the Committee boat by observing boards luffing. Multiply by three and set the windward mark at that angle downstream.

Obviously, from the example above, corrections may become very large. The Race Officer must decide what changes in tidal current will occur during the leg and during the race and set a course to allow for these keeping in mind the effects of the current on the off-wind legs.

8.8.4 Effect on downwind legs
In a cross-current, for a true downwind leg, the bottom mark should be downstream of the direction of the apparent wind. The distance it should be displaced is again dependent on the speed of the fleet. Thus, if a true windward beat is set (equal times on each tack) it is not possible to have a true run and arrive back at Mark 3. In fact, the first reach of the triangle may become a run and the second one a close reach. The leg from Mark 1 to Mark 3 would also be a reach. Unfortunately, the Race Officer must accept this effect on the off-wind legs in order to obtain better upwind legs.

8.8.5 General
Current and wind are unlikely to be parallel or at a 90 degree angle. The easiest method to determine apparent wind is to watch a competitor luffing head to wind.

To determine the correct bearing of the windward mark, have a board sail from the Starting vessel close-hauled on one tack for, say, one minute and then tack and sail on the opposite close-hauled course. The boards bearing when it has sailed for equal times on both tacks is the required bearing of the windward mark to give equal times on each tack.

A wing mark should be set at the usual bearings from the windward and leeward marks, although this will not give the required reaches. To give correct orientation of all legs, the marks would have to drift with the current with the course orientated towards the apparent wind from a drifting boat! Light winds and strong currents, particularly with slow boats, require large corrections.