We reserve the right to compare submitted measurements with our database of yachts already rated, and where significant differences in
hull dimensions exist, to substitute standard dimensions, unless suitable evidence is produced to support the measurements.
Please remember that the underlying principle of VPRS is to rate a boat on its performance potential. Anything that makes a boat go faster or
slower should be reflected in the measurements and hence the rating. The idea is not to look for, or to exploit, loopholes in measurement definitions.
Changes introduced for 2012 relate to Keel type and Upwind headsail as shown in red.
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VPRS data sources and accuracy
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Linear dimensions should be taken to the nearest centimetre.
Weights should be given to the nearest 10 kilograms.
When completing a rating application form you must indicate the
source
of each measurement by choosing one of the five following codes:
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A = Authenticated |
measurements made by the rating office or an appointed club measurer,
or taken from an endorsed IRC certificate for the vessel;
or provided by an approved sailmaker (see below).
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O = Owner measured |
for measurements that you have made. |
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P = Published |
measurements taken from published sources, including specifications from designers and manufacturers. Surprisingly
unreliable - regardless of source; design weights frequently not met during production.
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S = Sister ship |
measurements which have either been made on,
or taken from an endorsed IRC certificate of;
or taken from authenticated data on a VPRS certificate of;
a vessel of exactly the same type.
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X = Not known |
the system will either allocate an estimate, or where this is not possible,
the rating will be provisional until a measurement is provided.
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VPRS rating certificates and revalidation forms may also have the following data-source codes:
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D = Database derived |
for data derived from authenticated weights or measurements held for sister ships already
in the database. System use only. |
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E = Estimated |
for estimates that have been calculated by internal system routines.
Do not
estimate any measurements yourself - if a measurement is not available from any of the above sources, mark the field
with an 'X' on the application form. System use only. |
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Vessel weights which have been taken from sister-ship documentation will be re-assigned by the system and given a
'D' (database derived) classification. The value assigned will be calculated from authenticated sister-ship weights
held on the system and may relate to a number of sources including, but not limited to, current and expired rating data.
The aim is to record a weight for the vessel which is highly unlikely to exceed that which would otherwise have been
obtained by weighing.
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Please don't hesitate to contact us for advice
- if there is anything that you are unsure about. Weighing yachts is time-consuming and can be costly, so it's important to get a good result.
Ensure that, during lifting, insurances for both the vessel and public liability are operative.
When using a load cell to weigh a yacht, please note the following requirements:
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the vessel must be in the 'empty weight' condition - see below
the load cell must have a valid certificate of calibration, and a copy acquired
the load cell calibration error should not exceed +/-0.5% at the measurement point
the load cell should be able to resolve changes of +/-0.25% at the measurement point
if either load-cell tolerance is not met, any measurement error must not exceed 0.75%
the yacht must be hanging freely from a single-point lift
the yacht should be at rest
lifting equipment engines must be shut down
authenticated weights can only be recorded by a VPRS measurer
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Weighing can only be undertaken in calm weather. Wind speeds in excess of 10 knots are likely to introduce an offset error
on account of windage. Gusting winds will make the readings unstable.
The aim is to determine the boat weight to within 1%, taking into account errors arising from the conditions and
the accumulated load-cell errors.
Also remember that having the boat prepared in the 'empty weight' condition provides a good opportunity to
measure the bow, stern and topside overhangs, the transom height and the freeboard - refer to the measurement guide below.
In addition it is also possible to take a measurement, whilst alongside, which is needed to establish the draught.
The PDF link above captures all the information required for weigh-day - in one compact document.
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The following list of sailmakers can measure sails in accordance with this guide:
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Sanders Sails
North Sails
Batt Sails
Westaway Sails
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The measurement definitions provided below are arranged in the same groupings and order in which they appear
on an application form or rating certificate. Essential* and conditional(*) measurements are identified - and explained
at the end of each section. There are also PDF diagrams which illustrate many of the measurements, and for convenience
these open in a new window.
Yacht - identification
Most of the information at the top of the application form is self-explanatory. The following four items, however, sometimes need clarification.
Type State the type of mainsail/rig - usually Bermudian or gaff, and whether sloop, ketch, yawl
or schooner, and noting in addition if the yacht is a cutter. For example, 'Bermudian sloop' or 'gaff ketch'.
Design State where possible both the builder and model - and any additional information that helps to differentiate between
models with similar names. For example Laser 28, Beneteau First 29, Dehler 36 (00).
Series date The year when the model was first built. So, for example, the Dehler 36 CWS has a series date of 1988 whereas
the Dehler 36 (00) has a series date of 2000.
Build date The year when the yacht was built - which could be the same as the series date, or later.
Hull
Hull length* The overall length of the hull excluding the following: bowsprit and other rigging, stem
fittings, stern fittings, railings, rubbing strakes or any overhanging rudder and rudder hangings.
Bow overhang The horizontal distance from the point where the stem cuts the water to the forward limit
of the hull length, with the boat in the empty weight condition. If not submitted the bow overhang
will be estimated from the difference between the hull length and the waterline length.
Stern overhang* The horizontal distance from the point where the hull meets the water, ignoring any skeg,
to the aft limit of the hull length, with the boat in the empty weight condition. If not submitted the
stern overhang will be estimated from the difference between the hull length and the waterline length.
Waterline length* The horizontal distance between the point where the stem cuts the water and the point
where the hull meets the water at the stern, ignoring any skeg, and with the boat in the empty weight condition. Usually determined by subtracting the bow and
stern overhangs from the hull length.
Transom height* Vertical height from the surface of the water to the lowest point on the transom,
with the boat in the empty weight condition. For vessels with canoe sterns, measure vertically to the aft limit of the hull length.
Beam* The maximum width of the hull, as measured horizontally with the boat upright, and excluding rubbing strakes, toe rails or
other fittings. For a vessel with tumble-home, this will be at a point on the topsides.
Topside overhang Measured where the beam is a maximum (as determined above). The horizontal distance perpendicular
to the centre-line taken from the point where the side of the hull meets the water, to a point vertically below the point of maximum beam, with
the boat in the empty weight condition and upright. If not submitted, the topside overhang will be estimated as a proportion of the beam.
There is a drawing to illustrate this measurement.
Mean freeboard The average vertical height of the hull topsides, measured from the surface of the water to
the edge of the deck, with the boat in the empty weight condition. Calculated by taking the average of the freeboards measured at
the bow and stern. If not submitted, the mean freeboard will be estimated using a formula based upon the hull length.
Draught* The maximum depth below the surface, including the keel and rudder, with the boat in the empty weight
condition. If the boat has a lifting keel or rudder, the draught should be given with the keel and rudder fully down.
Empty weight* - for compatibility, as for IRC. Vessel to be prepared as described below.
Vessel to be fully rigged (spars, standing rigging, running backstays) and dry: the bilges, any other sumps, any raised sections
of the hull interior structure, and any sinks and toilets, must be empty.
In addition, the empty weight ...
includes: all halyards, main and mizzen sheets, spinnaker pole, bow sprit, engine (installed or on board), batteries,
fixed internal ballast and wash boards. Also includes all permanent fixtures and fittings for the accommodation - which must be in place.
Where any of these items are on board when meeting the empty weight condition, they must also be on board when racing.
excludes: all sails, headsail sheets and guys, spare rigging, the contents of all tanks (including ballast tanks),
anchors and cables, tools and spares. Additionally, all removable equipment (gas bottles, cooking and catering utensils, safety equipment
including life rafts), all clothing and bedding, and personal effects, must be removed from the vessel.
Tankage note: where the capacity is stated, or can be readily determined, tanks may instead be pressed up. In cases where it is
straightforward to determine the volume of the contents, no action need be taken.
The additional weights will be calculated with reference to capacities and specific gravities, and the total will be
subtracted from the measured weight.
Fixed Ballast weight The weight of the ballast keel and any internal ballast carried. Distinguish between the two
if possible. If not submitted the ballast weight will be estimated as a standard percentage of the empty weight.
Moveable ballast R/M If the yacht has moveable ballast such as water ballast tanks or a canting keel this field is
used to record the additional righting moment that it generates with the vessel upright. Please contact the rating office for assistance with completion
of this field.
Essential hull data: hull length, stern overhang, waterline length, transom height, beam, draught, empty weight.
Appendages & propeller
Keel type* Eight characters specifying the form and material of the keel,
assembled from codes (of two characters each) chosen in sequence from the following four categories: keel planforms, keel sections,
keel materials & 'other discriminating features'. The last category allows lifting/swing fins and additional ballast to be accounted for.
An example: Hustler 35 - T2P2F5N1; for which keel planform = T2, keel section = P2, keel material = F5 and 'other discriminating features' = N1.
Some others: Contention 33 - Z2P1R1N1; Beneteau First 260 Spirit - Z4P1R1S2; Beneteau First 285 - S1S1R3S1; Elan 410 - H2H5R2N1; Hanse 320 - R2R1R2N1.
You will need to refer to the Keel classification drawings.
NOTE that a selection must be made from each of the four categories above.
Keel depth The vertical distance between the bottom of the hull at its lowest point and the bottom
of the keel at its lowest point. Note that the vertical measurements required are frequently at different fore and aft positions; please
refer to the pdf diagrams. It will almost always be necessary to estimate where the lowest point of the hull would be without the keel.
If not submitted the keel depth will be estimated using a formula including waterline length and beam, and the displacement.
Keel chord The horizontal distance from the leading edge of the keel to the trailing edge, measured at half the
keel depth; please refer to diagram. Long keeled yachts with keel-hung rudders should exclude the rudder. If not submitted the keel chord
will be estimated using a formula including the keel depth and sail area.
Rudder type* Description of the rudder(s) including number, form/mounting and whether the rudder is fixed or lifting.
For example, 'spade', 'twin spade', 'skeg hung', 'keel hung', 'transom hung', 'twin transom hung'. The description submitted
will be converted to one of a number of standard phrases on the certificate.
Rudder depth For rudders that are usually wholly submerged, the vertical distance from the top of the rudder (and
skeg, if any) to its lowest point. For rudders that are partly out of the water (eg transom-hung rudders), the vertical
distance from the waterline to the lowest point of the rudder (and skeg, if any).
Rudder chord The horizontal distance from the leading edge of the rudder (and skeg, if any) to the trailing edge,
measured at half the rudder depth. For keel-hung rudders measure the rudder blade only.
Propeller type* Choose either 'none', 'fixed' or 'folding'. Vessels with outboard engines that are stowed with the propeller
out of the water when sailing should choose 'none'.
Propeller blades The number of blades on the propeller.
Propeller diameter The diameter of the circle described by the blade tips. For folding or feathering propellers, this
measurement should be given with the blades in the unfolded, working position.
Essential appendage and propeller data: keel type, rudder type, propeller type.
Rig
Spar material The principle material used for the spars, for example 'aluminium alloy', 'timber' or 'carbon fibre'.
Forestay length* The length measured from the point at which the forestay is attached to the deck (or bowsprit) and
to the point at which the forestay attaches to the mast, or to the point at which any upwind headsail is attached to the mast, if higher.
Foretriangle base* The horizontal distance from the front face of the mast to the point at which the forestay attaches to the deck (or
bowsprit), or to the point at which any upwind headsail is tacked, if further forward.
Sail construction State whether your mainsail and upwind headsail are of 'laminated' or 'woven' construction. If you have a mixture,
you must state 'laminated'. If not submitted, 'laminated' will be assumed.
Essential rig measurements: Forestay length, foretriangle base.
Mainsail
Mainsail hoist* The hoist of the mainsail measured on the mast, from the top of the boom or the mainsail tack whichever is
the lowest, and the bottom of a fixed 25mm band of contrasting colour at the top of the mast above which the mainsail shall
not be hoisted. If there is no band the measurement shall be taken to the top of the halyard shackle pin, when fully hoisted.
Mainsail foot* The foot of the mainsail measured along the top of the boom from the back of the mast to the inside of a
fixed 25mm band of contrasting colour beyond which the mainsail clew shall not be set. If there is no band the measurement
shall be taken to the aft side of the clew shackle pin when set fully aft.
Half width The shortest distance between the half leech point and the luff, bridging any hollows in the leech. If not
submitted the half width will be assumed to include a roach and will be estimated from the mainsail foot.
Three-quarter width The shortest distance between the three-quarter leech point and the luff, bridging any hollows in the
leech. If not submitted the three-quarter width will be assumed to include a roach and will be estimated from the mainsail foot.
Upper width The shortest distance between the 7/8th leech point and the luff, bridging any hollows in the leech. If
not submitted the upper width will be assumed to include a roach and will be estimated from the mainsail foot.
Mainsail reefing State the reefing method, one of 'slab', 'roller', 'in-mast' or 'in-boom'.
If not submitted, 'slab' will be assumed.
Essential mainsail measurements: mainsail hoist, mainsail foot.
Mizzen
Mizzen hoist* The hoist of the mizzen sail measured in the same way as the mainsail hoist.
Mizzen foot* The foot of the mizzen sail measured in the same way as the mainsail foot.
Staysail luff length* The longest luff length of any mizzen staysail, measured in the same way as the headsail luff length.
Staysail luff perpendicular* The longest luff perpendicular of any mizzen staysail, measured in the same way as the headsail luff perpendicular.
Essential mizzen measurements: All.
Upwind headsail
An upwind headsail is a sail tacked forward of the foremost mast that can be used to sail close to the apparent wind. It may be
attached to a stay or have a loose luff. The working area of the largest sail used for this purpose should be measured with
reference to the shape of the sail when it is set.
Luff length* The shortest distance from head to tack when stretched sufficiently to remove creases - placing
one or two flakes along the luff will help considerably.
Luff perpendicular* The shortest distance from the clew to the luff or part of the sail that behaves as the luff. For a cutter the
luff perpendicular is measured as the shortest distance from the aftmost clew of any upwind headsail when set on the centre line of the boat,
to the foremost forestay.
Half width(*) The shortest distance between the half leech point and the luff, bridging any hollows in the leech
of the sail. If not submitted the half width will be estimated from the luff perpendicular.
Three-quarter width(*) The shortest distance between the three-quarter leech point and the luff, bridging any
hollows in the leech of the sail. If not submitted the three-quarter width will be estimated from the luff perpendicular.
Headboard width Dropped for 2012.
Foot height When sailing close-hauled, the height of the foot (midway between tack and clew) above the deck.
If it touches the deck then record the measurement as 0m. Where not submitted a value calculated from the other upwind headsail dimensions, applying a degree of
performance advantage, will be used.
Reefing State the primary reefing method, either 'change sail' or 'roller'. When stating 'roller' then
other upwind headsails may only be used if they do not result in a higher rating; you can apply for a trial certificate to check this.
If not submitted, then 'change sail' will be assumed.
Essential upwind headsail measurements: luff length and luff perpendicular. For boats where the
luff perpendicular is less than 110% of the foretriangle base, the half width and three-quarter width must also be submitted.
Downwind headsail
A downwind headsail is a sail set forward of the foremost mast from three corners only, with half width greater than 75% of the foot
(measured as defined below). It may be symmetrical or asymmetrical. Examples include spinnakers and cruising chutes.
The working area of the largest sail used for this purpose should be measured with reference to the shape of the sail when it is set.
Tack type* State how the sail is tacked, one of 'spinnaker pole', 'bow sprit' or 'deck'.
Pole or tack length* The length - using the longest spinnaker pole or bowsprit and measured on or near the
centre line of the boat - from the forward face of the mast to the extremity of the pole or sprit, or the horizontal length from the
forward face of the mast to the spinnaker tack point on deck, whichever is the greatest.
Leech length(*) The leech length of the largest downwind headsail, measured with the sail pulled taught from the clew to the head. For
a symmetrical sail the designation of leech and luff is arbitrary, so long as both are measured.
Luff length(*) The luff length of the largest downwind headsail, measured with the sail pulled taught from the tack to the head. For a
symmetrical sail the designation of leech and luff is arbitrary, so long as both are measured.
Half width(*) The distance between the half leech and half luff points, with the sail held taught between the two.
Foot width(*) The distance between the tack and clew, with the sail held taught between them.
Area(*) If measurements for leech and luff lengths, half width and foot width are given, VPRS will calculate the area. Alternatively, state the area
given by your sailmaker, as calculated for a spinnaker under IRC.
Essential downwind headsail measurements: tack type, pole or tack length, AND either area OR leech length, luff length, half width and foot width.