Note on Handicap System
Cruiser Handicap Update 2023
We continue to use handicap formulae for single and bilge keel boats that are part of the generic group of LinStat models. For more information and background see my statistical modelling blog https://blogs.city.ac.uk/linstat/. The models used for ESSC cruiser handicaps generate equivalents of Portsmouth Numbers. These numbers are different from those given by many other handicap systems in that they are time divisors, rather than multipliers. Portsmouth numbers (PN) yield a time correction factor multiplier given by .1000/ PN
Annually we look at whether there are grounds to apply any variations to the listed handicaps, based on modelling developments, data checking and, in the light of performance, possible 'club' adjustments. Club adjustments are restricted to the range -20 to +20 points and do not apply to inter-club races. No adjustments were made for the 2022 season because the race data for 2021 was not as informative as would be liked, in that less than half the competing boats completed at least 3 race days, which is the minimum we consider to be appropriate on which to base potential adjustments. So, the 2021 race data have been combined with the 2022 race data to provide a basis for possible club adjustments in the 2023 season. Boats completing at least 5 races over the two seasons have been considered for adjustment. Where there is little relevant race data for a boat over the last four years or so, earlier club adjustments have been reset.
Occasionally, there are boat characteristics which are in some way unusual and information on suitable handicap adjustment limited. In those circumstances, every effort will be made to estimate an adjustment which is both fair to the boat concerned and to the rest of the boats in the fleet. Once a season of performance data is to hand, suitable changes may be made.
In keeping with the relevant club rules, a WSO ('white sails only') adjustment may be applied to a handicap number. This has in the past been an uplift of 3%, but this has been updated to 2.5% in the light of a range of information and practice.
Formulae 2023
The handicap/rating formulae, authored by me and described online, use basic boat data where all measurements are metric. Some data are qualitative, for example keel shape. In relation to fin keel boats for example, a 'long' keel or various shapes that result in a lowering of the keel centre of gravity relative to a standard 'flat' fin keel will attract handicap adjustment in the range -0.3% to 1.8%. All boats are subject to further adjustments in respect of certain sail features and engine configuration.
Adjustments 2023
| Rig features | twin mast ketch | +2% |
| in-mast reefing | +2% | |
| high-tech sails (-0.5% for one HT sail) | -1% | |
| Engine related | 3 blade fixed propeller | +2% |
| folding/feathering propeller | -1% | |
| outboard (able to be lifted clear of the water) | -2% |
Linda Wolstenholme, April 2023
Last updated 21:15 on 1 April 2024