The IRC certificate includes a DLR number (Displacement/Length Ratio) which is sometimes used to help determine class splits, for instance between racers and cruiser/racers.   DLR is calculated as follows:

DLR = (27.87 * IRC Displacement) / LWP^3      (Help with mathematical formulae)


a) LWP = LOA – BO – SO
b) IRC Displacement is directly related to Empty Weight. Any addition to Empty Weight will be reflected by an identical increase in IRC Displacement.
c) The calculated value of DLR is rounded to the nearest integer value for printing on each boat’s certificate with 0.5 rounding upwards.