Some technical guidance please, from my learned colleagues, as follows:

The term hull length or hull lengths is expressed in a few rules (generally to specify distance to a mark or from another boat etc), and while not a defined term within itself, it is used in other DEFINITIONS (i.e. Continuing Obstruction, Obstruction and Zone); similarly in the Case Book.

For those purposes, how is hull length (HL) actually measured though: length on deck (LOD) – excluding protrusions (e.g. a bow roller, bowsprit or sugar scoop etc) or length overall (LOA) – including a sprit or waterline length (WL) or otherwise strict measurement basis?

Finally, given relevant rules where hull length or hull lengths is used (e.g. 18.2 (a) (1))): how relevant to some classes with lengthy flying sail sprits or bowsprits is this (e.g. my own racing yacht has a fixed 2.5mtr flying sails sprit) – and conversely the opposing boat does not?