VPRS 


Home  About  System  Apply  Measurements  Stability  Rated yachts  Authors 
We reserve the right to check submitted measurements against our database of yachts and, where significant differences in hull dimensions exist, to substitute standard dimensions  unless suitable evidence in support of those submitted is available. Remember that the principle of VPRS is to rate a boat on its performance potential. Anything that alters this should be reflected in the measurements and hence the calculated rating. The idea is not to look for, or to exploit, loopholes in the measurement definitions. This guide (below, and in PDF format, top right) describes the data and measurements required for a rating certificate. VPRS employs standard Universal Measurement System (UMS) data, abbreviations and methods wherever possible, so data is interchangeable with other rating systems including IRC and ORC. More information is available in World Sailing's Equipment Rules of Sailing (ERS).
Ensure that during lifting, insurances for both the vessel and public liability are in place. When using a load cell to weigh a yacht, please note the following requirements:
Yacht  identification Most of the information at the top of the application form is selfexplanatory. The following four items, however, sometimes need clarification. Rig type State the type of mainsail/rig  usually Bermudian or gaff  and whether sloop, ketch, yawl or schooner, noting in addition if the yacht is a cutter. For example, 'Bermudian Sloop', 'Gaff Ketch', 'Bermudian yawl cutter'. Design If possible state 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 design 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 to be rated was built. Hull Hull length (LH)* The length of the hull excluding the bowsprit and other rigging, stem and stern fittings, railings, rubbing strakes or any overhanging rudder and rudder hangings. Bow overhang (BO)* 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. Stern overhang (SO)* 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. Must either be measured or determined from the hull length, the bow overhang and the waterline length. Waterline length (LWL)* 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, with the boat in the empty weight condition. Usually determined by subtracting the bow and stern overhangs from the hull length. Stern height (Y)* The vertical height from the surface of the water to the aftmost point on the hull moulding, with the boat in the empty weight condition. If the aftmost point is underwater, record a stern height of zero. For yachts with an outwardsloping transom which is out of the water, first drop a vertical line from the aftmost point of the hull. Then project the underside of the hull and mark the point where it intersects with the vertical line. Measure the vertical height from the water to this point. Beam (MB)* The maximum width of the hull, measured horizontally with the boat upright and excluding rubbing strakes, toe rails or other fittings. For a vessel with tumblehome, this will need to be taken between points on the topsides. Topside overhang (TSO) The horizontal distance from the point where the side of the hull meets the water, to a point vertically below the point of maximum beam (see above) with the boat upright in the empty weight condition. Best taken as an average of port and starboard measurements to reduce the error arising from any list. If not submitted, topside overhang will be estimated as a proportion of the beam. There is a drawing to illustrate this measurement. Mean freeboard (FBI) The vertical height of the hull topsides, adjacent to the mast, measured from the surface of the water to the edge of the deck with the boat in the empty weight condition. If not submitted, the freeboard will be estimated using a formula based upon the hull length. Draught (T)* The maximum depth below the surface, including the keel, with the boat in the empty weight condition. If the boat has a lifting keel then the draught should be given with the keel fully down.
Empty weight (EW)* The empty weight condition is as follows:
Fixed Ballast weight (KW) 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 If the yacht has moveable ballast such as water ballast tanks or a canting keel or both, then this is noted here; choose either 'None', 'Water', 'Canting keel' or 'Ctg keel & Water'. Please contact the rating office so that the appropriate measurements can be determined. The additional righting moment available as the vessel heels will be calculated. Essential hull data: hull length, bow overhang, stern overhang, waterline length, stern height, beam, draught, empty weight. Appendages & propeller
Keel type* Eight characters (comprising 4 pairs) which specify the form and material of the keel.
The twincharacter codes are 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.
Keel depth (KD) The vertical distance between the bottom of the hull (canoe body) 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 which includes the waterline length and beam, and the displacement.
Keel chord (KC) 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 keelhung rudders should exclude the rudder. If not submitted the keel chord will be estimated using a formula which includes the keel depth and the 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 (RD) 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 transomhung rudders),
the vertical distance from the waterline to the lowest point of the rudder (and skeg, if any).
Rudder chord (RC) 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 keelhung rudders measure the rudder blade only. Propeller type* Choose either 'None', 'Fixed', 'Feathering' or 'Folding'. Vessels with outboard engines that are stowed with the propeller out of the water when sailing should choose 'None'. Propeller blades (PRN) The number of blades on the propeller. Propeller diameter (PRD) 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. Mizzen Mizzen hoist (PY)* The hoist of the mizzen sail measured in the same way as the mainsail hoist. Mizzen foot (EY)* The foot of the mizzen sail measured in the same way as the mainsail foot. Staysail luff length (LLY)* The longest luff length of any mizzen staysail, measured in the same way as the upwind headsail luff length. Staysail luff perpendicular (LPY)* The longest luff perpendicular of any mizzen staysail, measured in the same way as the upwind headsail luff perpendicular. Essential mizzen measurements: All. Rig Spar material The principal material used for the spars, choose either 'Aluminium alloy', 'Timber' or 'Carbon fibre'. Forestay length (FL)* 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 (J)* 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. Essential rig measurements: Forestay length, foretriangle base. Mainsail Mainsail hoist (P)* 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. The mainsail may not be hoisted above the band. If there is no band the measurement shall be taken to the top of the halyard shackle pin, when fully hoisted. For a gaff rig, the hoist is measured to the peak of the mainsail, unless a topsail is to be used, when it is measured to the head of the topsail. Mainsail foot (E)* 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. The mainsail clew may not be set beyond the band. If there is no band the measurement shall be taken to the aft side of the clew shackle pin when set fully aft. 1/2 width (MHW) 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. 3/4 width (MTW) The shortest distance between the threequarter leech point and the luff, bridging any hollows in the leech. If not submitted the threequarter width will be assumed to include a roach and will be estimated from the mainsail foot. Upper width (MUW) The shortest distance between the seveneighth 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. Sail construction State either 'Laminated' or 'Woven'. If any mainsail to be set whilst racing is of laminated construction then choose 'Laminated', otherwise choose 'Woven'. If not submitted, then 'Laminated' will be assumed. Mainsail reefing State the reefing method, one of 'Slab', 'Roller', 'Inmast' or 'Inboom'. If not submitted, 'Slab' will be assumed. Essential mainsail measurements: mainsail hoist, mainsail foot. Upwind headsail An sail set 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. For cutters, only the luff length and luff perpendicular are required. Luff length (HLU)* The shortest distance from head to tack when stretched sufficiently to remove creases  placing one or two flakes along the luff will help considerably. For a cutter, the luff of the sail set on the foremost forestay should be measured. Luff perpendicular (HLP)* 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 foremost forestay to the aftmost clew of the headsails when set on the centreline of the boat. 1/2 width (HHW)(*) 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. 3/4 width(HTW)(*) The shortest distance between the threequarter leech point and the luff, bridging any hollows in the leech of the sail. If not submitted the threequarter width will be estimated from the luff perpendicular. Foot height (HFH) When sailing closehauled, 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. Sail construction State either 'Laminated' or 'Woven'. If any upwind headsail to be set whilst racing is of laminated construction then choose 'Laminated', otherwise choose 'Woven'. If not submitted, then 'Laminated' will be assumed. Reefing State the primary reefing method, either 'Change sail' or 'Roller'. When stating 'Roller' then, with the exception of a storm jib, other upwind headsails may only be used where the area does not exceed 67% of the rated headsail area; we can check this for you. 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 threequarter width must also be submitted. Downwind headsail 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. Vessels rated with a spinnaker pole may also tack the sail to a sprit or deck fitting. Vessels rated with a sprit may also use a deck attachment but not a pole. Vessels rated with a deck attachment may use neither pole nor sprit. In all cases the rating will be calculated using the greatest tack length and the largest sail area. Note that 'Code 0' sails should be measured as downwind headsails. If the half width is greater than 75% of the foot then the sail is confirmed as a downwind headsail. If the half width is less than 75% of the foot the sail must be remeasured as an upwind headsail. The boat will then be rated with the 'Code 0' as its upwind headsail. Tack type* State how the sail is tacked, one of 'Spinnaker pole', 'Bow sprit' or 'Deck'. Pole or tack length (STL)* 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. Luff length(*) (SLU) 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. Leech length(*) (SLE) 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. 1/2 width(*) (SHW) The distance between the half leech and half luff points, with the sail held taught between the two. Foot width(*) (SFL) The distance between the tack and clew, with the sail held taught between them. Area(*) (SPA) 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. 
