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US Sailing Universal Measurement System (UMS) Measurer Seminar. High Performance Rule (HPR) Overview Jim Teeters. Why HPR?. Rule is customized for high performance boats Type-form to fast design – low performance boats not competitive Ability to plane offwind in medium breeze
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US SailingUniversal Measurement System (UMS)Measurer Seminar High Performance Rule (HPR) Overview Jim Teeters
Why HPR? • Rule is customized for high performance boats • Type-form to fast design – low performance boats not competitive • Ability to plane offwind in medium breeze • Public (open spreadsheet rule calculator) • Simple (measure ONLY the fundamental characteristics that determine speed) • Leave details to designers to simply create fast boats. • No subjective elements
HPR Design Features • Characteristics of contemporary grand prix • Light displacement, wide beam, high sail area promote offwind planing • Deep draft, modern fin/bulb keels, low VCG for upwind speed • Long waterlines relative to LOA • High sail area, long sprits, flat had mains.... • No moveable ballast
What is Rated? • Rated Length = LOA (overhang credits for old boats) • Max Beam, Draft, Displacement • Upwind Sail Area, Spinnaker Area, Rig Height • Freeboard – mild encouragement of interior volume • VCG – surrogate for stability • Crew Weight • Propellers • Construction Credit, Old Age Credit
What is Not Rated? • Details of hull shape: (no offsets files required) • No wetted areas, LCBs, prismatic coefficients • No details of appendage design: wetted area, volume • No heeled stability (VCG and beam act as surrogates) • Intent: Adopt some of the rationale behind box rules: minimize design optimization of trading off design details, leave freedom to designer to find fastest solutions, encourage development
Type-forming • Default boat – based on rated length: • Beam, draft, displacement, freeboard.... • Upwind sail area, spinnaker area, rig height... • VCG, crew weight • Rating based on deviation from default boat • Limited credits for being slower • Limited penalties for being faster • Credits/penalties initially calibrated with VPP
VCG Determination • Method 1 – Component Weighing • Mast weight and VCG • Boom weight • Total weight from scale • Keel weight and VCG • Canoe + rudder weight imputed, VCG coefficient • Method 2 – Offsets File + In-Water Flotation • VPP hydrostatics, salinity correction • Sensitive to environment: wind/waves...
Keel Weight/VCG • Requirements • Two lift points: bulb and keel top • Keel top can be anywhere, typically at keel bolts • Lift points and support points must be vertically aligned • Axis of lifting lines must be vertical • Keel blade must be horizontal when lifted • All distances are relative to bottom of keel