BRacing Reference Tools

Sections in this chapter

B.1Start and first-beat decision framework
B.2Racecourse observation and briefing template
B.4Post-race debrief template
B.5Performance-data glossary and calculation conventions

This appendix turns the theory of chapters 9 to 12 into procedures the crew runs unchanged at every regatta and audits afterwards. Section B.1 is the start and first-beat decision framework: a fixed sequence from time base and line-bias measurement through transits, side selection, position choice, bail-out triggers and the first-cross plan, so that a poor start is traced to the step that failed rather than to a general impression. Section B.2 is the observation and briefing template that feeds the framework, listing what the crew observes before the warning signal, how each item is observed and what it implies for the racecourse model. Section B.4 is the post-race debrief template, ordered by race phase and by category of loss, so that each loss is attributed once and to a cause that can be trained. Section B.5 fixes the vocabulary and calculation conventions for performance data, including the definitions used by the trackers and analytics platforms the crew will meet, and states the rule that the crew's own logged values are the reference wherever no published 49er figure exists.

B.1Start and first-beat decision framework

The framework is run in order, and each step produces a value or a decision that the next step consumes. Steps 1 to 5 are decided before the preparatory signal, steps 6 to 9 run in the final approach, and steps 10 to 12 govern the first beat. A step that is skipped is recorded as skipped, so that the B.4 debrief can attribute the outcome.

Fix the time base and the penalty regime. Timers start on the class flag at five minutes and are checked against the preparatory flag at four minutes and its removal at one minute, taking times from the visual signals because "the absence of a sound signal shall be disregarded" S1. The preparatory flag is recorded because it sets the cost of being over: round an end under the I flag, a 20 percent scoring penalty under Z, disqualification unless the race is restarted under U, and disqualification that survives a restart under the black flag S1.
Measure the line bias. The crew luffs head to wind near the middle of the line, reads the compass bearing and compares it with the bearing of the line sighted along the two ends; for every 5 degrees of upwind bias to one end, that end is ahead by about one eighth of the line length, measured as distance sailed on a close-hauled course S65. The reading is repeated at intervals up to the final approach, because the wind covers a range from a few degrees to as many as 40 degrees S52, and is one sample of that distribution rather than the bias.
Set the transits. The line is located by sighting through both ends to a fixed object ashore S51, and two or three transits are taken at each end, one on the line, one over and one behind S66. The transit is taken from the eye that will use it at the gun, helm or crew, and the boat end is re-sighted whenever the committee boat swings on its anchor.
Take the preferred side from the racecourse model. The beat is classified from the B.2 briefing as oscillating, one side clearly advantaged, or everything else, in which case the boat sails conservatively toward the middle and consolidates S62. Position on the line follows that plan, pin end for the left and committee-boat end for the right, and a strongly favoured side overrides the line bias S51.
Set the risk budget from the series position. "Some starting approaches are riskier than others" S64, and the percentage principle is to "Go for many little gains rather than one big gain" S51; the crew states before the preparatory signal which approach is chosen and what result the series needs from the race, so that the choice is not remade under pressure in the last minute.
Choose the position and the hole. The target is a leeward gap wide enough to bear away and reach full speed before the gun, and a windward neighbour that cannot roll the boat before it is at speed; tracking at the 2015 49er Europeans showed a of 10 m and a starboard-tack advantage of under one second in time to the line after the gun, measured on speed over ground S16. Distance behind the line at the start lengthened the race in the 49erFX study with a of 0.060 S37, so the hole is held with the bow on the transit taken behind the line rather than a length behind it.
Run the time-and-distance approach. The approach is worked back from the outcome wanted S64: the turn-in point, the acceleration distance and the seconds needed to reach full speed are the crew's logged values, crew value seconds from crew value lengths, and the countdown is called against them. Where tracking equipment is permitted under S3, the logger's and distance-to-line S79 are checks on the call, not substitutes for it.
Apply the bail-out triggers. The boat leaves the hole when any one of these holds: the leeward gap has closed so that bearing away is no longer possible, the boat is early with no room to slow without stalling, a leeward boat is bow-forward and will hold the boat in bad air, or the time to line at the achievable speed, plus the acceleration margin, exceeds the time remaining. Under the U flag or the black flag the only acceptable bail-out is early and to leeward or astern of the fleet, never across the line S1; a port-tack duck of the fleet is considered only when the starboard time-to-line advantage is small, as the under-one-second figure from the 2015 data indicates it can be S16.
Exit at speed and secure the lane. Speed comes before pointing in the first lengths, because dirty air from a boat on or to weather of the bow forces a tack "within 6 to 10 boatlengths (the greater distance is in lighter conditions)" S56, while a safe-leeward position gives "a lift and more pressure as the wind bends around the front of their sailplan" S54. The crew holds the lane while it is clean and tacks only when the tack goes toward the preferred side or the lane is already lost.
Execute the first-cross plan. The plan states before the gun which side of the first cross the boat wants and which tack crosses; leverage is bounded by the model, because a 5-degree shift changes the relative position of two boats by 12 percent of their lateral separation, measured as distance sailed on a close-hauled course S52. In an oscillating breeze the boat tacks on headers to stay on the lifted tack, and in a persistent shift it sails toward the side closer to the expected wind direction S51; VMG on the first beat carried a coefficient of -2.0 in the 49erFX study, "almost ten times that of any other skill" S37, so the cross is never bought with speed.
Consolidate and measure in ladder rungs. Gains are read on rungs perpendicular to the wind, the boat that has climbed higher being ahead S53, and the rule is "When you make a gain on other boats, consolidate by crossing ahead of them" S51. The boat stays "away from the corners and laylines" S51, and reaches a layline only with the top-mark approach already decided.
Approach the top mark. Near the mark any shift is played as a persistent shift S51, because laylines "are definitely a dead end when the wind is shifting" S51; the zone is three hull lengths, mark-room under rule 18 depends on whether the boats are overlapped when the first of them reaches it, and in reasonable doubt "it shall be presumed that she did not" S1. An inside position approaching the mark is worth fighting for S51, "considerably prior to bearing away" S12, and the set is called before the zone.

B.2Racecourse observation and briefing template

The table lists what the crew observes between launching and the warning signal, how each item is observed from the boat or the coach boat, and what it implies for the racecourse model. The briefing that follows states the model in a fixed order so that nothing is omitted and the plan can be compared with the outcome in B.4. Every observation is logged with its time, because the model is a distribution over the race window rather than a snapshot.

Observation	How to observe	What it implies
Forecast wind and	Read the , its trend and the model source before launching; global models run at 9 km (ECMWF) S45 and about 13 km (GFS) S46, regional models at 1.3 km (AROME) S47 and 2.5 km (HARMONIE) S48, and kilometre-scale models represent sea breezes better S49.	for direction, trend and sea-breeze probability; boundary-layer winds "are backed and decreased from the geostrophic values" S38, so the surface wind is expected left of and below the gradient value.
Wind direction, mean and range	Log head-to-wind bearings at fixed intervals on a compass permitted under S3, with the time of each; sail both tacks close-hauled and log the headings.	The mean and the range define the oscillation, which covers a few degrees to as many as 40 degrees S52; periods run from about 3 minutes in heavy air to 10 minutes or more in light-medium air, with from 5 degrees in light-medium air to 40 degrees in heavier air S50, which sets how many shifts fit in a beat. A drifting mean indicates a persistent shift from a front, or a shoreline S52.
Pressure distribution	Scan at , at least 200 to 500 metres, for stronger wind on one side and for backs and clocks S50; log where gusts arrive from and how they travel.	The surface is roughly with gusts carrying 30 to 40 percent extra speed S50; the biggest downwind gains and losses often come from wind-speed differences across the course S51, and sailing in pressure is the key priority in light and medium air S63. A side with more pressure justifies leverage that direction alone would not.
Cloud	Identify upwind of the course, whether it is raining, and its drift relative to the course.	A cumulus gives "a 'lefty' on the left side of the cloud and a 'righty' on the right side" looking upwind S41; the wind decreases as a non-raining cumulus approaches, is null overhead and increases once it has passed, while under a raining cloud "the wind speed increases and the wind shift arrives before the rain" S44.
Current indicators	Read the wake on fixed references, "lobster pots, moored boats, or even the choppiness of the water" S68 and "current ribbons, trap buoys, birds and fish" S69; check the anchored committee boat and marks; compare heading with course over ground on the log.	: with current toward the windward mark a boat tacking on the wind-only layline overstands, and in adverse current the boat tacks away early "while you're in the weaker current" S68. A boat cannot gain by pinching to put the current on its lee bow S67; a current gradient across the course is a strategic side in its own right.
Wave direction per tack	Sail each tack close-hauled and note the angle between the bow and the dominant wave train, whether a second train is present, and the steepness and period.	Leftover waves at an angle to a new breeze put one tack into the waves and the other across them, so each tack needs its own mode S77. raises wave height and wind with current lowers it S76, and "If the wind and current are aligned, the water is smoother than when the current runs against the wind" S51, which is itself a current reading.
Sea-breeze signs	Note the land-sea temperature difference, cloud over the land, the strength and direction of the gradient wind and the time of day; watch the offshore water for a new wind line.	A sea breeze needs a land-sea temperature difference of 5 °C or more, blows typically near 6 m/s and rotates clockwise through the day in the Northern Hemisphere S42; it is expected when an offshore gradient wind is under 25 knots with thin or broken cloud S43, fills first offshore and moves toward land as a mini-front S51, and "may move roughly 5 degrees per hour" once established S52.
Shoreline and topography	Map the shore relative to the course and the wind, noting where the wind blows off the land, along it or onto it.	Friction turns the surface wind about 30 degrees over land and generally less over water S39, and the left turn over land in the Northern Hemisphere "often leads to " S40; bends, bands and shifts near shores are the venue's structure S43 and are recorded in the venue file.
Course geometry	Take the bearings of the first mark and the line, the length of the line and of the first beat, and the positions of the gate and the finish; measure the line bias by the head-to-wind method.	For every 5 degrees of upwind bias, one end is ahead by about one eighth of the line length, measured as distance sailed on a close-hauled course S65. Ladder rungs perpendicular to the wind S53 convert the mark bearing and the mean wind into the leverage available on the beat; at the gate the mark farther upwind is closer and the down-current mark turns faster S58.

Briefing order. The helm states the model aloud and the crew confirms or corrects each line before the warning signal.

Wind: mean direction crew value, range crew value, period crew value, and the persistent trend with its cause if one is expected.
Pressure: which side carries more, how far up the course, and the direction in which gusts travel.
Current: direction and strength by area of the course, and the layline correction it implies at each mark.
Waves: the mode on starboard and the mode on port, taken from the sea-state matrix in A.2.
Sea breeze: expected or not, the earliest time and the direction it would arrive from.
Plan A: the preferred side, the first-cross tack and the leverage limit for the first beat.
Line: bias in degrees and in line lengths, the transits held, and the end chosen.
Plan B: the observation that triggers the switch, and the plan it switches to.
Rules in force: the preparatory flag, the rule 42 penalty for the event (one turn replaced the two-turns penalty at Paris 2024 and the 2025 World Championship S4 S5), and the protest time limit (two hours after the last boat finishes by default under rule 60.3 S1, cut to 60 minutes at the 2025 World Championship S5).

B.4Post-race debrief template

The debrief runs in the order of the race so that each phase is assessed against the plan stated in the B.2 briefing, and each loss identified is then assigned to exactly one primary category from the second table. The order of effort follows the evidence: the 49erFX study found that "having a good start and an efficient first beat is the most important combination to sailing a shorter race" S37, so the debrief spends its time where the says the time went. Data come from the crew's own log and, where available, from the per-boat metrics that SAP publishes, gap to leader, average speed over ground, distance travelled, number of manoeuvres, and S78, which the class makes part of the post-regatta routine S17; gain-and-loss comparisons between boats are built from the log files S31.

Phase	What the debrief establishes	Data checked
Start	Whether the bias, the end and the hole matched the briefing; the gap to the line at the gun against the 10 m minimum seen in the 2015 tracking S16; whether a bail-out trigger fired and whether the response followed B.1 step 8; speed at the gun relative to the neighbours.	Distance to line and at the gun, speed over ground in the first lengths, position along the line, flag in force.
First beat	Whether the boat sailed the planned side within the leverage limit, tacked on headers or on the model's persistent call, kept its lanes clean, and held VMG at the crew's target for the wind band, the leg carrying the coefficient of -2.0 in the 49erFX study S37.	Leg VMG, cross-track error, number of tacks and , the logged shift sequence against the briefed range.
Top mark	Whether the layline call was made outside the zone, which shift the boat played as persistent S51, whether overlap and mark-room under rule 18 were established without doubt S1, and whether the vang was released before the bear-away S12.	Approach track relative to the layline, time inside the zone, set time from the mark.
Run	Whether the mode chosen, "the high road or the low road" S29, matched the pressure and the fleet, whether the boat gybed on lifts and sailed toward pressure S51, and whether any covering gybe was made two to three lengths away S57.	Leg VMG, speed over ground per gybe, number of gybes and loss per gybe, distance sailed against the fleet.
Gate	Whether the mark chosen was the one farther upwind, the least crowded or the down-current mark S58, whether a pinwheel at the right-hand mark was avoided S59, and whether the drop left the boat close-hauled before the bow reached the mark S51.	Rounding speed, exit heading against the second-beat plan, drop timing.
Second beat	Whether the plan was revised on the shifts and pressure seen on the run, whether covering, tight or loose S51, was applied to the boats that mattered for the series score, and whether the boat stayed away from corners and laylines S51.	Leg VMG against the first beat, cross-track error, gain and loss per boat covered.
Finish	Whether the downwind end was identified as the favoured end and the lifted tack aimed at it for an upwind finish S61, or whether a downwind finish was approached from 50 to 100 yards outside the line to avoid a late gybe S60.	Final-leg track, time to the line from the last manoeuvre, places gained or lost on the leg.

Category of loss	Definition	Typical evidence	Trained by
Handling	Loss inside a manoeuvre or a recovery: tack, gybe, set, drop, capsize, or a beyond the "+/- 5 degrees" that is acceptable S36.	A speed and VMG dip in the manoeuvre window larger than the crew's reference loss crew value; unplanned manoeuvres, with the caution that the 49erFX study associated extra manoeuvres on the first and last legs with shorter race times S37.	Manoeuvre drills, chapter 8, weighted toward strong wind, where places the priority on manoeuvring efficiency S30.
Mode	Loss on a straight line from the wrong mode or trim for the conditions: the high or low road misjudged S29, pointing when speed was needed, the wrong wave mode for the tack S77.	Speed over ground and VMG below the log's target for the wind band with no manoeuvre and no tactical cause.	Two-boat testing, chapters 6 and 7.
Tactical	Loss from a positioning decision: a lane lost, the wrong side, an early layline, a cover missed, the wrong gate mark, the wrong finish end.	The gain-and-loss comparison against the boats that made the other choice S31; cross-track error larger than the plan allowed.	Racecourse model and tactics, chapters 10 to 12.
Environmental	Loss from a shift, pressure, current or wave feature that the model did not predict or the crew did not observe.	A logged shift or pressure outside the briefed range; a current set different from the briefing; a sea breeze earlier or later than expected.	Observation template B.2 and the venue file.
Rules	Loss from a penalty, a protest, or a right-of-way situation avoided at a cost: a rule 42 penalty under Appendix P S2, the one-turn penalty at events that prescribe it S4 S5, a rule 30 start penalty S1, or a duck taken because rights were unclear.	A penalty taken, a protest hailed and filed within the limit of rule 60.3 S1, or a recorded avoidance manoeuvre.	Rules study, chapter 13.

Each loss receives one phase, one primary category, the crew's estimate of its cost in metres or places from the log, and one consequence: a change to the racecourse model, to the base settings, or to the training plan. The list is filed with the race so that categories can be counted across a regatta and a season, and the category with the largest cumulative cost sets the priority of the next training block. A race with no identified loss is debriefed against the fleet's tracked metrics, because a clean race that was still slow is a mode problem until proved otherwise.

B.5Performance-data glossary and calculation conventions

The glossary defines each term as the crew uses it and notes where a tracker or an analytics platform defines or reports it differently. No published 49er polar or wind-band target table was found, so the crew's own logged values are the reference for every target quoted in this book; published metrics serve for comparison between boats and never as targets.

Term	Definition	Convention and published usage
Speed over ground (SOG)	Speed of the boat relative to the sea bed, derived from successive GNSS positions; it includes the current component.	The crew's log at the logger's rate is the reference; the Vakaros Atlas 2 uses a 25 dual-band GNSS receiver and logs at 2, 5 or 10 Hz S79, and SAP publishes average speed over ground per boat S78. Speed through the water is SOG with the removed and is not logged directly.
Course over ground (COG)	Direction of the boat's motion over the sea bed, in degrees.	It differs from heading by leeway, 3 to 5 degrees upwind in medium breeze on most racing boats S23, plus the current set; the Sailmon MAX records heading and position separately S80, so leeway plus set is read as the difference between the two.
True wind	The wind relative to the water, given by direction and speed; the crew's reference direction is the head-to-wind compass bearing logged on the water.	Trackers estimate it: the Sailmon MAX records "" S80, a derived quantity, which is compared with the crew's logged bearings before it is used. A true wind relative to the ground differs from one relative to the water by the current vector.
Apparent wind	"The of the TRUE WIND and the BOAT COURSE" S19: the wind experienced on the boat, which as boat speed rises increases in speed and moves forward in angle S26.	The primary steering and trim reference on the boat; it is not recorded by the GNSS loggers listed here and is reconstructed from true wind and boat motion when needed.
VMG	: SOG multiplied by the cosine of the angle between COG and the true wind direction, taken toward the wind upwind and away from it downwind.	Computed on the crew's logged true wind direction, not on the mark bearing; SAP publishes leg VMG S78 and the Vakaros reports VMG S79 on their own wind estimates. Upwind and downwind values are not compared with each other: the Olympic-class GPS study found VMG higher downwind than upwind, with both rising with wind speed S30.
	The class definition: "the extra distance sailed upwind from course middle line on either side" S17, published per boat by SAP S78.	The crew logs it as signed lateral distance from the rhumb line between the marks, left negative and right positive, and the leg value as the maximum excursion and the mean; the two are different quantities and are not interchangeable, so the log states which is meant; the leverage limit in B.1 step 10 is stated in the same units.
Distance sailed	Length of the over-ground track integrated from position samples over a leg or a race; SAP publishes it as distance travelled S78.	Sample rate changes the value, so comparisons are made only between logs at the same rate; found distance travelled rising with wind speed on both legs S30.
Distance to line	Perpendicular distance from the bow to the start line at a given instant, in metres.	Reported by the Vakaros Atlas 2 S79; the 2015 49er Europeans tracking showed a of 10 m S16, and in the 49erFX study distance behind the line at the start carried a of 0.060 on race time S37.
	Distance to line divided by the component of SOG toward the line, in seconds; time to burn is the time remaining to the gun minus time to line, and the boat arrives by the gun only where the time to burn is at least the acceleration margin of B.1 step 8.	Reported by the Vakaros Atlas 2 with time-to-burn S79; the 2015 tracking gave starboard tack an advantage of under one second after the gun, measured on SOG S16. permits tracking equipment only "where permitted by the ICA, Notice of Race and/or Sailing Instructions" S3, and Paris 2024 prohibited data transmissions while racing S4.
	The distance, in metres of VMG, by which the boat's track over a manoeuvre window falls short of the track it would have sailed at its pre-manoeuvre VMG for the same time.	The window opens when the helm is first moved to begin the turn and closes when VMG returns to its pre-manoeuvre value; the reference loss per tack and per gybe by wind band is crew value. SAP publishes the number of manoeuvres per boat S78, not the loss.
Leverage	The lateral separation between two boats measured perpendicular to the true wind direction.	It prices a shift: a 5-degree shift changes the relative position of two boats by 12 percent of their lateral separation, measured as distance sailed on a close-hauled course S52. The leverage limit in the first-beat plan is stated in metres and derived from the briefed range.
Ladder rungs	Lines perpendicular to the true wind direction; upwind the boat on the higher rung is ahead S53, and downwind the boat on the lower rung is ahead.	Position in the fleet is read in rungs rather than in distance along the rhumb line, and the gain from a shift is the change in rung difference.

Calculation conventions.

Reference values: targets for speed, VMG, angle and manoeuvre loss are the crew's own logged values by wind band; no published 49er polar or wind-band table was found, and polars built from the crew's log files, as Njord does from log data S31, are the crew's own product.
: bands are defined by the crew's logged crossover values crew value, not by fixed wind speeds; published study ranges, such as 5.5 to 11.6 knots for the 49er in the Olympic-class GPS study S30, bound what those studies can say about the crew's conditions.
Units and references: speeds in knots, distances in metres, angles in degrees; wind direction relative to the water; a shift to the right, clockwise, is positive.
Sampling: the log rate is fixed for a season, 2, 5 or 10 Hz on the Atlas 2 S79, and recorded in the file header; distance sailed and manoeuvre loss are compared only at equal rates.
Legs: a leg starts at the start signal or a mark rounding and ends at the next rounding or the finish; the first beat is the leg to which the -2.0 coefficient of the 49erFX study applies S37.
Precedence: where a published metric and the crew's log disagree, the crew's log is the reference, and the difference is noted alongside the metric's definition rather than resolved by averaging.