World Human Powered Vehicle Association - Competition Rules

Revised August 2008 - Pending Ratification by WHPVA Board

 

1.0 PURPOSE

The World Human Powered Vehicle Association (WHPVA) supports human-powered
vehicle competition and ratifies and maintains performance records for the purpose of
promoting advancements in human-power technology.

2.0 GENERAL

These rules apply to human-powered vehicle competition in three categories:
1. Land
2. Water
3. Air
Within these categories, records are maintained in the classes of competition outlined
below. The WHPVA ratifies and maintains records but assumes no responsibility for the
attempts themselves. Observation and verification of record attempts is the responsibility
of WHPVA member organisations.

3.0 LAND VEHICLE COMPETITIONS

3.1 Vehicle Requirements
3.1.1 Power: Vehicles must be driven solely by human power. Non-human power sources (batteries, solar cells,
etc.) are permitted only for powering sensors, displays, communication equipment and lights. Control devices,
cooling fans, powered aerodynamic devices, etc., may not be powered from non-human sources.
3.1.2 Energy Storage: No device which stores energy over more than one input power cycle (e.g., one leg
stroke), or which releases energy under control of the operator, may be used in any event except the
road race, or speed events longer than one mile. Energy storage devices are permitted in these events
provided no energy is stored before the start of the event. This means absolutely no chemical, electrical,
kinetic, potential, or other form of energy storage at the start. This includes phase-change vests or ice
packs.
3.1.3 Brakes: All vehicles must have a safe means of stopping.
3.1.4 Control: All vehicles must be controlled by the rider(s), with the single exception of that necessitated by
the standing start as described in section 3.2.3.1.
3.1.5 Integrity: No vehicle may discard any part after beginning motion.
3.1.6 Geometry: The vehicle geometry may not be alterable during use except for steering purposes; i.e. sails
or moving control surfaces specifically intended to enhance the sailing characteristics of the vehicle are
not permitted.
3.1.7 Vehicle Classes: Vehicles shall be recognised in the following classes:
3.1.7.1 Open: Any human powered land vehicle.
3.1.7.2 Restricted or Part-faired: To be defined.
3.2 Events
3.2.1 Competition Classes: Competition events shall be recognised in the following classes:
3.2.1.1 Single Rider: The vehicle shall contain only one person.
3.2.1.2 Multiple rider: The vehicle shall contain two or more persons.
3.2.1.3 Arms only: Competitors may use arms only power in all WHPVA events; land, water and air. It will
be deemed a separate event category if the rules in section 3.4 “Arm Power Rules” are met. Event officials
may request separate arm power events for safety or practical purposes.
3.2.1.3.1 Physically handicapped riders: Rules to be determined. Event Directors may institute special
competitions in this area.
3.2.1.4 Male and female riders: The WHPVA shall recognise separate records for males and females in all
events.
3.2.1.5 Organiser's option: Classes may be combined by the event organiser for a single race, but all records
will be maintained in the classes indicated.
3.2.2 Types of Events: The following race events are recognised:
3.2.2.1 200 Metre Speed Trial: The winner of this event shall be the vehicle achieving the highest average
speed over a 200 metre interval. A flying start from any distance is permitted, within practical limits as
established by the event organiser.
3.2.2.2 200 Metre Speed Trial, 600 metre start: Highest average speed over a 200 metre interval. Flying start
from not more than 600 metres before the 200 metre timed section.
3.2.2.3 500 Metre Speed Trial: Identical to 3.2.2.1 except 500 metres.
3.2.2.4 1 Kilometre Speed Trial: Identical to 3.2.2.1 except 1 kilometre.
3.2.2.5 4 Kilometre Speed Trial: Identical to 3.2.2.1 except 4 kilometres and standing start.
3.2.2.6 10 Kilometre Speed Trial: Identical to 3.2.2.1 except 10 kilometres and standing start.
3.2.2.7 100 Kilometre Speed Trial: Identical to 3.2.2.1 except 100 kilometres and standing start.
3.2.2.8 1 Mega-Metre (1,000,000 metres) Speed Trial: Identical to 3.2.2.1 except 1,000,000 metres and
standing start.
3.2.2.9 1 Mile Speed Trial: Identical to 3.2.2.1 except 1 mile.
3.2.2.10 1/4 Mile Elapsed Time: Shortest elapsed time to travel 1/4 mile. Standing start.
3.2.2.11 1-Hour Time Trial: Maximum distance in one hour. Closed course. Standing start. Distance is
determined by direct measurement. Alternatively, the time trial distance may be calculated from the
course length and lap timings.
3.2.2.9.12 1-Hour Time Trial, Velodrome: Maximum distance in one hour on closed course of
maximum 500m length. Standing start. Distance is determined by direct measurement. Alternatively,
the time trial distance may be calculated from the course length and lap timings.
3.2.2.13 12-Hour Time Trial: Same as 3.2.2.9 except 12 hours.
3.2.2.14 24-Hour Time Trial: Same as 3.2.2.9 except 24 hours.
3.2.2.15 Road Race: Winner is the vehicle to first complete a designated number of laps on a
designated course, or travel the longest distance within a designated time period. Standing start, flying
start or LeMans start. No records shall be recognised for this event.
3.2.2.16 Practical/Commuter Vehicle: Rules to be determined.
3.2.2.17 Special Records Events: Members are encouraged to submit
applications for new record categories to the WHPVA. Significant achievements may be recognised as
new record classes.
3.2.3 Starts
3.2.3.1 Standing Start: A standing start is an unassisted start from the stationary position, except that
vehicles which are unstable at low speeds may be assisted by one assistant and optional technical
support gear for not more than 15 metres. The assistant may not push the vehicle.
3.2.3.2 Flying Start: A flying start is where the vehicle may accelerate before entering the timed portion
of the course. Push assists by one or more persons are permitted. Pushers may not assist the vehicle for
more than 15 metres.
3.2.3.3 LeMans Start: A LeMans start is where the vehicles are parked diagonally on one side of the
race course, while the riders line up on the other side of the track. At the start of the race, the riders run
to their vehicles, get in, and proceed onto the course. Push assists are not permitted. However, if any
vehicle is unstable at low speeds, a single assistant is permitted to stabilise the vehicle for not more
than 15 metres. The same assistant may also assist the rider in getting into the vehicle, closing
canopies, etc.
3.2.4 Drafting: No human-powered vehicle may be assisted in any record attempt by a pacing vehicle
used for the purpose of aerodynamic assistance.
3.2.5 Change of Riders: No change of riders or removal of riders is permitted during a race.
3.2.6 Passing: In multiple-vehicle races, lapped vehicles must yield right-of-way to lapping vehicles.
Blocking or obstructing the race path by weaving is prohibited. Vehicles should follow a steady
predictable line during a race and avoid sudden manoeuvres which might cause accidents.
3.2.7 Safety Requirements
3.2.7.1 Helmets: All riders shall wear helmets during all competition. Helmets must meet the standards
of a nationally accredited testing facility of any WHPVA member country.
3.2.7.2 Vehicle Safety: Vehicles may be disqualified from competition due to inadequate braking
capability, lack of stability, poor visibility, presence of dangerous protrusions, or other unsafe design
features.
3.2.8 Conduct: Any competitor judged by the event organiser(s) to be riding without regard for the
safety of others or deliberately obstructing other competitors may be disqualified from that particular
event.
3.2.9 Illegal Substances: The competitor may be subject to tests for drugs or other substances designed
to enhance athletic performance that may be defined as illegal by the International Olympic Committee
at the time of the attempt. Detection of illegal substances will invalidate the attempt.
3.3 COURSE REQUIREMENTS
3.3.1 Course Flatness: Except for courses for the road race events, and time trial events one hour and
over, all courses must meet the following flatness requirement: If an imaginary line is drawn from the
end of the timed portion of the event course back toward the beginning of the course but sloped upward
at a slope of 2/3 percent (1 metre in 150), at no point may the vehicle course pass above this line.
Curved courses may be used for any event, provided the same flatness requirement is met. The 200
metre time trap in the 200 metre speed trial events, however, must be contained in a straight section. All
curved courses must be clearly marked with the limiting inside boundary. Any vehicle crossing a wheel
over this boundary shall be disqualified from the run. Course distance shall be measured from the
inside boundary of turns.
3.3.2 Course Measurement: In order to qualify as a record course, distances and elevation difference
must be measured and certified by a registered Civil Engineer, a registered Land Surveyor, or a person
with equivalent training.
3.3.3 Timing: All timing must be accomplished by automatic start and stop actuation. Timers must be
certified as accurate to within 1/100 of a second in 10 minutes or 1 second per day at a temperature of
20 degrees/C, plus or minus 5 degrees/C. Certification must be by a chronographic testing service or a
registered Electrical Engineer. Timing to the nearest 1/100 second is required, and timing to the nearest
1/1000 second is preferred. 3.3.4 Wind: For any run to be approved as a record, except as noted in
section
3.3.4.1 below, the wind velocity in any direction must not exceed 6 (six) kilometres per hour (1.67
metres per second). Wind velocity measurement must be taken during the duration of the actual timed
run at the finish of the course, at a level of 2 metres above the course surface. These restrictions apply
to closed and straight courses.
3.3.4.1 Wind Restrictions for Long Duration Events: There are no wind restrictions for time trial events
of one hour or longer, or for distance events of 100 km or greater, provided the event is held on a close
course, at least one full lap is completed, and the impact of up- and downwind portions of the track is
balanced. The geometry of vehicles competing under this rule shall be fixed: there will be no sails or
moving control surfaces specifically intended to enhance the sailing characteristics of the vehicle.
3.4 ARM POWER RULES
3.4.1 Power: Power from the rider(s) to vehicle momentum shall be transmitted by way of rider(s) arm
and hand movements only. Upper torso above hips may contribute such power output. No part of a
rider's leg or foot shall contribute to upper body power output for gaining and maintaining vehicle
momentum.
3.4.2 Control: No restrictions, but must meet all WHPVA vehicle control requirements as set forth in
general rules.
3.4.3 Qualification: Any rider may compete in arms only events provided they meet all arm power
rules.

3.5 DOCUMENTATION

Written documentation of a record attempt must be submitted to the sanctioning WHPVA Member Organisation
within 30 days after the attempt. This shall include:
• The date, time and location of the attempt.
• The names of the vehicle designer(s), builder(s), and rider(s) and the name(s) of the person(s) or
organisation(s) applying for the record.
• Photographs of the vehicle, or acceptable drawings.
• Evidence of timer calibration and accuracy.
• Evidence of course measurement and accuracy.
• A statement that all of these regulations and conditions have been complied with, signed by the
applicant and both observers.
• A record of the environmental conditions during the whole attempt.
• Speed and direction of wind
• A videotape showing the attempt, starting procedure and compliance with these regulations and
conditions is highly recommended.
See also WHPVA OBSERVER GUIDELINES.

4.0 WATER VEHICLE COMPETITION RULES

4.1 VEHICLE REQUIREMENTS (PURE HUMAN POWER CLASS)
4.1.1 Power: Vehicles must be driven solely by self-contained human power. Nonhuman power sources
(batteries, solar cells, etc.) are permitted only for powering sensors, displays, communication
equipment, or lights. Control devices, cooling fans, aerodynamic and hydrodynamic devices must be
human powered. Some exceptions may be allowed, but must be approved in advance of any attempt by
the WHPVA Records Committee. Power may not be extracted from wave energy or wind and water
currents, except momentarily in such a way that the overall effect during the attempt does not constitute
an advantage when compared to the same attempt without these conditions, or within the tolerances
specified in Appendix B.
4.1.2 Energy Storage: In events with a flying start the accumulation of the kinetic energy of vehicle and
rider(s) is permitted in accordance with rule 4.2.3.2. Other forms of energy storage are permitted
provided this energy is created within the timing section of an attempt and provided its source is human
power. No pre-start storage is allowed. See Appendix B and also rule 4.1.1 regarding instrument
batteries.
4.1.3 Propulsion: Propulsion must be provided entirely by hydrodynamic and/or aerodynamic devices.
Any type of fluid-dynamic propulsion device is allowed. Particular characterisations of propulsion, e.g.
oars, propellers, paddle wheels, or those not covered by these rules (e.g. punting) may be divided into
separate sub-classes. Riders may use any and all parts of their bodies for propulsion (except for the
'Arms Only' class defined in rule section 4.2.2.3.)
4.1.4 Control: Vehicle control forces must be provided by onboard rider-controlled mechanical,
hydrodynamic, or aerodynamic device(s). The onboard rider(s) must control the vehicle; other
person(s) or means must not control the vehicle. Auto-steering devices under the direct control of the
rider are permitted.
4.1.5 Integrity: No materials may be jettisoned for aiding propulsion or lightening the craft other than
unadulterated water or air collected during the attempt. The rider must ride on or in the vehicle.
4.1.6 Support: All types of devices directly or indirectly supported by the water are allowed. This
includes displacement and planing craft, hydrofoils, hovercraft, and craft having moving skins or
tracks. Vehicles using an “air cushion” or “ground effect” are permitted, whereas craft capable of free
flying are not. Records characterised by the type of support, e.g. displacement craft, or underwater
craft, are considered sub-classes (see 4.2.1.2). The rider(s) and vehicle must be able to begin and end
any attempt fully afloat and essentially stationary with respect to the water. For the passage through the
iming section itself, see 4.2.3.
4.1.7 Rider Attributes: Any number of active riders of either gender may power the vehicle. The gender
and number of riders constitute a class distinction, e.g. single-rider, women. Those who request a class
distinction for other physical attributes: youth, senior, physical size, physical disability, etc. may
request such distinction from the WHPVA Records Committee. Approval must be completed prior to
any record attempt.

4.2 WATERCRAFT CLASS EVENTS
4.2.1 COMPETITION CLASSES: A complete list of watercraft classes maintained, and events within
those classes, are shown in Appendix A. The WHPVA web site at http://www.WHPVA.org may contain
updated Appendix information. The following class types are recognised for events:
4.2.1.1 Pure Human Power Class: Watercraft must meet the requirements as defined in section 4.1 to be
automatically recognised as such.
4.2.1.2 Sub-Classes: Classes that do not meet the requirements of the Pure Human Power Class as
defined in section 4.1 are called sub-classes. The WHPVA may record or publish achievements in subclasses
that are regarded as worthwhile. The rules governing sub-classes are the same as for the
watercraft Pure Human Power Class with the exception of the particularities in question. The sub-class
must be qualified by these particularities, if possible within its name.
4.2.1.3 Other Achievements in Watercraft: A record attempt, which nearly fits into an existing class but
does not fulfil all requirements, may be recognised as an "outstanding achievement" or "qualified
record" within the existing class, provided that the particularity of the attempt is clearly recognisable.
An "outstanding achievement" or "qualified record" within an existing class may include class records
maintained by other organisations.
4.2.1.4 New Classes: New classes may be started at any time but will not necessarily be maintained or
published by the WHPVA until added to the class list by the WHPVA Records Committee at its
discretion.
4.2.2 CLASS CATEGORIES: For the purpose of event records within the watercraft Pure Human
Power Class, the following categories shall be recognised (class categories in Sub-Classes must be
separately approved. See Appendix A):
4.2.2.1 Single Rider: The vehicle shall contain only one person.
4.2.2.2 Multiple Riders: The vehicle shall contain two or more persons. Multirider classes may be
gender mixed.
4.2.2.3 Arms Only Riders: Deemed a separate category when following rules are met:
4.2.2.3.1 Power: Power from the rider(s) to vehicle momentum shall be transmitted by way of rider(s)
arm and hand movements only. Upper torso above the hips may contribute to arm and hand power
output. No part of a riders leg or foot shall contribute to upper body power output for gaining and
maintaining vehicle momentum.
4.2.2.3.2 Control: No additional restrictions, but must meet all WHPVA vehicle control requirements as
set forth in the watercraft rules.
4.2.2.3.3 Qualification: Any riders may compete in arms only events provided they meet all power
rules. Riders who have disabilities that prevent them from meeting all requirements of section 4.2.2.3
may request a waiver from the WHPVA Records Committee (in advance of attempt) so they may
legally compete in this category. However, such request will not be granted if doing so would give the
rider(s) a significant competitive advantage over others in this class.
4.2.2.4 Male and Female Riders: The WHPVA shall recognise separate records for male and female
riders in events. Multi-rider vehicles with both male and female riders shall have no class distinction
based on gender.
4.2.3 STARTING AND FINISHING
4.2.3.1 Standing Start: The rider(s) and vehicle must be at rest and fully afloat behind the starting line
when the event timing starts.
4.2.3.2 Flying Start: The vehicle may accelerate over an unlimited distance prior to entering the timed
portion of the course. All watercraft momentum gained prior to the timing section must be made by
human powered efforts of the rider(s) as required in other sections of these rules.
4.2.3.3 Finishing: Finishes may always be timed “flying”, i.e. with the vehicle moving.
4.2.4 DRAFTING: A vehicle may not be aerodynamically or hydrodynamically assisted by the
presence or action of any other vehicle or device. It is accepted that passing vehicles may momentarily
cause assistance (see section 4.2.6.)
4.2.5 CHANGE OF RIDERS: No change of rider(s) or removal of rider(s) is permitted during an event.
Rider(s) may remove themselves for reason of illness or emergency and the record attempt continued if
this does not result in an advantage over the normal situation. Records with defined rider changes are
possible under appropriate sub-classes.
4.2.6 PASSING: In events where multiple vehicles are on a course at the same time, vehicles being
overtaken from behind, such as being lapped, may not obstruct the path of others on course by weaving
or deliberate obstruction of the course. Vehicles should follow a steady predictable line during an event
and avoid sudden manoeuvres that might cause accidents. Event observers shall make judgements on
passing disputes.
4.2.7 SAFETY REQUIREMENTS: Safety shall be paramount at all times and is the responsibility of
the entrant. The observers must be satisfied that the course is safe; attempts will not be observed under
unsafe course conditions or if the the competitors create unsafe conditions through their behaviour or
riding style.
4.2.7.1 Personal Flotation Devices: Riders must in general carry one Personal Flotation Device
(sometimes known as "life vests") on board for each person and wear them as instructed by the
observers or event organiser. This requirement may be waived in closely supervised attempts or if
equivalent buoyancy aids are worn. Riders are required to keep their own safety in mind and wear their
life vests if there is a reason to, such as bad weather, cold water, known weaknesses of craft or rider(s),
or not being able to swim. The standard and use of the flotation device must meet local legislative
requirements and should reflect the conditions. People, craft, or courses with special risks should
warrant the use of appropriate flotation devices and not just buoyancy aids.
4.2.7.2 Buoyancy: The vehicle must be buoyant under normal event conditions or when capsized. The
event organiser may waive this requirement if they supervise each attempt closely and provide for the
safety of the rider(s) and for any required recovery of the craft(s).
4.2.7.3 Additional Safety Requirements: The observers must be satisfied that the rider can exit the
vehicle unassisted and has effective protection from injuries. Official observers may require additional
safety equipment such as paddle(s), bailer, line, whistle, and flag. Safety equipment should be agreed
upon in advance of attempt. For long distance events in open waters, additional pyrotechnic and radio
means are recommended.
4.2.8 CONDUCT: In the case of record attempts carried out during race meetings or similar events, any
competitor judged by the event organiser to have misbehaved during an event may be disqualified from
that particular event.
4.2.9 ILLEGAL SUBSTANCES: The competitor may be subject to tests for drugs or other substances
designed to enhance athletic performance that may be defined as illegal by the International Olympic
Committee at the time of the attempt. Detection of illegal substances will invalidate the attempt.
4.3 WATERCRAFT COURSE REQUIREMENTS
4.3.1 COURSE LAYOUT: The course shall be defined as the shortest possible path between the start
and finish line, which may include markers that must be passed in a specified manner. A speed
measurement shall be made by measuring the elapsed time over the specified distance.
4.3.2 COURSE MEASUREMENT: The distance of a course shall be measured and certified by a
registered Civil Engineer, licensed Surveyor, or equivalent. Markers establishing the distance must be
firmly attached to the earth, either on shore, on driven piles or by other means not subject to drift due to
current or wind. The start/stop actuators or transits for timing shall be located at these positions. The
measurement error must be indicated and the course lengthened by at least this error, i.e. if the
measurement error is 0.1 m, the nominal 100 m course must be laid out as 100.1 m, but 100.0 m used in
any further calculations for speed.
4.3.3 COURSE DEFINITION: Courses can have the same or different start and end points, but must be
continuously measured, i.e. it is not permissible to consider the average of a number of runs as a record.
4.3.4 ENVIRONMENTAL FACTORS: It must be proved plausibly that there is no net environmental
power input or advantage due to potential energy difference during the attempt except for the allowable
tolerances. Ways of establishing this and the currently allowable tolerances are described in Appendix
B. Vehicles which do use environmental energy over the tolerated amount are considered in a sub-class
of environmentally-assisted vehicles. There are no restrictions regarding altitude.
4.3.5 WATER: The water must be liquid (no ice boats) and be of a temperature and salinity as found in
natural bodies of water. The depth must be sufficient that no support is derived directly or indirectly by
the bottom. See Appendix B.
4.3.6 TIMING: Timing equipment must have a resolution of at least 0.1 s except for long distance
events where 1 second is sufficient. Timing results must be rounded in the unfavourable direction or
accepted statistical methods applied (and documented) in the case of multiple timing devices. Methods
such as Video-Timing or Global Satellite Positioning are allowed if it can be shown that they are
suitable, sufficiently accurate, and calibrated. Videotape documentation of events is highly
recommended; see section 4.4.
4.4 DOCUMENTATION
Written documentation of a record attempt must be submitted to the WHPVA within 30 days after the
attempt. This shall include:
• The date, time and location of the attempt.
• The names of the watercraft designer(s), builder(s), and rider(s) and the name(s) of the person(s) or
organisation(s) applying for the record.
• Photographs of the vehicle, or acceptable drawings.
• Evidence of timer calibration and accuracy.
• Evidence of course measurement and accuracy.
• A statement that all of these regulations and conditions have been complied with, signed by the
applicant and both observers.
• A record of the environmental conditions during the whole attempt:
• Speed and direction of wind
• Speed and direction of water current(s)
• Water conditions (sea state and type of water body, water depth if relevant. See Appendix B)
• A videotape showing the attempt, starting procedure and compliance with these regulations and
conditions is highly recommended.

5.0 AIR VEHICLE COMPETITION RULES

To be determined.

6.0 OBSERVERS

All record attempts must be sanctioned by an WHPVA member organisation and witnessed by at least
two observers appointed by the sanctioning organisation. Observers should be independent of the
competing team and qualified by training or experience for observation. The responsibility of observers
is to establish that WHPVA Competition Rules have been followed for an attempt, record all
information relevant to the attempt, and provide the sanctioning national organisation with an
Observers’ Report.

7.0 RATIFICATION

The WHPVA will ratify record performances organised under these rules. In order for a record to be
ratified, the sanctioning national organisation must file a request for ratification together with the
completed Observers’ Report for the attempt, with the WHPVA Record Committee within 45 days of
the event. At least one member of the competing team must be a current member of an WHPVA
member organisation.

8.0 ALL COMERS RECORDS

Records will be recognised on a national basis, and by general geographic area, such as Europe, North
America, Africa, etc. The best performance in a given country or general area shall be the All Comers
Record, regardless of the nationality of rider or machine. The best performance between All Comers
Records in different countries shall be the World Record.

9.0 RULES CHANGES

Any member of an WHPVA member association may recommend a change of rule to the WHPVA
Board.

Appendix A

WHPVA Watercraft Classes and Events
• 100 metre flying start speed trial -Men, single rider
• 100 metre flying start speed trial -Women, single rider
• 2,000 metre standing start speed trial -Men, single rider
• 24 hour metre standing start speed trial -Men, single rider
• 24 hour metre standing start speed trial -Multiple riders

Appendix B

WHPVA Watercraft Environmental Tolerances and examples
Wind and Current: Attempts may be disallowed if observation notes show that wind or water currents may
have contributed to an improved average course speed (inclusive of flying start run-ups) when
compared with a hypothetical no-wind or no-current situation. Favourable winds and currents which
result in a speed advantage of less than 1% may be tolerated if this can be adequately and accurately
shown. Measurement errors must be specified except in cases where it is clear that even large errors
have no relevance.
Examples (these are not rules, but suggestions for showing their fulfilment):
Water currents:
Water surface current can easily be measured by timing and sighting a floating orange. Except near the
inflow and outflow of rivers, the water current in lakes is usually negligible except for the windinduced
surface current.
Wind:
Wind strength can be measured by a variety of instruments either instantaneously or by averaging
during the duration of the attempt. Accuracy is not important as long as it can be shown that there is no
net power gain. For example with unstreamlined vehicles, if there is a favourable gust this can be
discounted if there is at least an unfavourable gust from the opposite direction with at least the same
duration.
Wind direction can be measured instantaneously by a number of devices: wind vanes, streamers,
smoke, or soap bubbles. The wind direction can be considered constant if it varies only slightly during
the attempt in the experience of the observers, otherwise the deviations must be recorded.
Streamers such as a simple woollen thread, smoke, etc. are extremely sensitive and can show very low
wind strengths and their direction. Some axial vane devices are very sensitive and if set up in the
direction of the run will count both forward and backward, thus immediately showing the average wind
component strength and direction. A negative (i.e. headwind) count is sufficient evidence to prove no
wind assistance at the location of the instrument provided that the true wind direction is shown to be at
an angle of less than 45 degrees for completely unstreamlined craft and less than 10 degrees for highly
streamlined craft or craft using air propellers. In cases of doubt it is suggested to gather sufficient
measurements for the record committee to decide.

General

What counts is the experience, integrity, and common sense of the observers. Clearly, a round-course
will not cancel environmental effects if currents and winds are non-uniform and happen to coincide
favourably with the course, e.g. a large eddy in the same direction, or an exposed downwind leg and a
sheltered upwind leg. Equally, any craft with the least sailing capabilities will gain most by travelling at
right angles to the wind. Or, any craft with both air and water propellers will be capable of exploiting
slight differences in wind or current in any direction.

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