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

Carkeek 40s Decision, Spookie, Denali^2

McConaghy 38

Mills Concept

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

Rating SummaryFinal CalculationLength L 12.3100Age Plus Pre HPR AGEc 0.9620Beam BMc 0.9991Freeboard FRc 1.0000Draft DRAc 0.9958VCG VCGc 0.9738Crew Factor CFc 0.9997Displacement Demptyc 0.9940Upwind Sail Area USAc 0.9984Spinnaker Area SPAc 0.9936Rig Height RHc 0.9955Robust Mast RMASTc 1.0000Appendage Apc 1.0000Engine-Propeller EPc 0.9829Construction Cost CCc 0.9900

Preliminary Rated Length == > 10.9562Rated Length Lower Limit == > 10.8328

Final Rated Length ======= > 10.9562TCF 0.9554Seconds per mile 577.7

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

Type-forming

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

www.hprsailing.org