RuleLength

The Rule length $L$ is the distance, in metres, measured on the waterline at the scantling draught from the fore side of the stem to the after side of the rudder post, or the centre of the rudder stock if there is no rudder post. $L$ is not to be less than 96%, and need not be greater than 97%, of the extreme length on the waterline at the scantling draught. In ships without rudder stock (e.g. ships fitted with azimuth thrusters), the Rule length $L$ is to be taken equal to 97% of the extreme length on the waterline at the scantling draught. In ships with unusual stern and bow arrangement the Rule length $L$ will be specially considered.(ref. IACS S2 Definition of Ship's Length $L$ and of Block Coefficient $C_b$ - S2.1 Rule Length).