Below are descriptions of the formulas we are using to calculate additional boat performance parameters. These formulas are not part of the Rules and Bylaws.
Some of the formula descriptions here refer to parameters that are defined in our Rules and Bylaws. These include:
Largest Mainsail Area – MainSA
Largest Jib Area – JibSA
Largest Symmetrical Spinnaker Sail Area – SymSpinSA
Largest Asymmetrical Spinnaker Area – AsymSpinSA
You can find the formula definitions for the above parameters in the Rules and Bylaws.
Last Updated November, 2022
| Description | Short Name | Formula | Variables | |
|---|---|---|---|---|
| Traditional Hull Speed | HS | 1.34*SQRT(LWL) | LWL=length at waterline | |
| Dave Gerr Hull Speed | GHS | 8.26/((D/LWL)^0.311) * SQRT(LWL) | D=displacement; LWL=length at waterline | |
| Windard/Leward Sail Area | SA-WL | (SA-Up+SA-Dn)/2 | ||
| Displacement/Length Ratio | DLR | D/LWL | D=displacement; LWL=length at waterline | |
| Displacement/Length Ratio Long Tons | DLR-LT | (D/2240)/(LWL/100)^3 | D=displacement; LWL=length at waterline | |
| Sail Area / Displacement Ratio Upwind | SAD-Up | (MainSA +JibSA)/(D/64)^(2/3) | MainSA=mainsail area; JibSA=jib area; D=displacement | |
| Sail Area / Displacement Ratio Downwind | SAD-Dn | (MainSA +(MAX (JibSA,SymSpinSA, AsymSpinSA)))/(D/64)^(2/3) | MainSA=mainsail area; JibSA=jib area; SymSpinSA=symmetrical spinnaker area; AsymSpinSA=asymmetrical spinnaker area; D=displacement | |
| Sail Area / Displacement Ratio Windward/Leward | SAD-WL | (SAD-Up+SAD-Dn)/2 | SAD-Up=upwind sail area; SAD-Dn=downwind sail area | |
| S Number Upwind | Sno-Up | 3.972*10^(-1*DLR-LT/526+0.691*(LOG(SAD-Up)-1)^0.8) | DLR-LT=displacement length ratio long tons; SAD-Up=sail area displacement ratio upwind | |
| S Number Downwind | Sno-Dn | 3.972*10^(-1*DLR-LT/526+0.691*(LOG(SAD-Dwn)-1)^0.8) | LT=displacement length ratio long tons; SAD-Dn=sail area displacement ratio downwind | |
| S Number Windward/Leward | Sno-WL | (Sno-Up+Sno-Dn)/2 | ||
| Modified Performance Factor Upwind | mPF-Up | ((0.66*LWL) + (0.34*LOA)) * (SA-Up)/D | LWL=length at waterline; LOA=length overall; SA-Up=upwind sail area; D=displacement | |
| Modified Performance Factor Downwind | mPF-Dn | ((0.66*LWL) + (0.34*LOA)) * (SA-Dn)/D | LWL=length at waterline; LOA=length overall; SA-Dn=downwind sail area; D=displacement | |
| Modified Performance Factor Windward/Leward | mPF-WL | (mPF-Up+mPF-Dn)/2 |